* Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 20:52 ` [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG zijianzhang
@ 2024-04-09 21:18 ` Willem de Bruijn
2024-04-10 0:08 ` [External] " Zijian Zhang
2024-04-09 21:18 ` Eric Dumazet
` (4 subsequent siblings)
5 siblings, 1 reply; 24+ messages in thread
From: Willem de Bruijn @ 2024-04-09 21:18 UTC (permalink / raw)
To: zijianzhang, netdev
Cc: edumazet, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu, Zijian Zhang
zijianzhang@ wrote:
> From: Zijian Zhang <zijianzhang@bytedance.com>
>
> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
> However, zerocopy is not a free lunch. Apart from the management of user
> pages, the combination of poll + recvmsg to receive notifications incurs
> unignorable overhead in the applications. The overhead of such sometimes
> might be more than the CPU savings from zerocopy. We try to solve this
> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
> This new mechanism aims to reduce the overhead associated with receiving
> notifications by embedding them directly into user arguments passed with
> each sendmsg control message. By doing so, we can significantly reduce
> the complexity and overhead for managing notifications. In an ideal
> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
> flag, and the notification will be delivered as soon as possible.
>
> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
The idea to avoid POLLERR and errqueue receive cost by piggy-backing
onto the send() call is appealing.
I also implemented this when initially adding MSG_ZEROCOPY. At the
time my implementation did not warrant the modest performance
improvement I measured. But this may be different.
The main reason my code was complex is that this requires changes
to net/socket.c: controldata is intended to be user->kernel on
send and kernel->user on recv, such as data. This feature breaks
that. You'll have to copy msg_controldata in ____sys_sendmsg.
I don't think it requires this much new infrastructure: a separate
queue in structs tcp_sock and udp_sock, a differente uarg callback.
I would suggest an optimistic algorithm, whereby the send call
steaks a notification skb from the error queue if present. This
could be a new mode set with a value 2 in SO_ZEROCOPY.
> ---
> include/linux/skbuff.h | 7 +-
> include/linux/socket.h | 1 +
> include/linux/tcp.h | 3 +
> include/linux/udp.h | 3 +
> include/net/sock.h | 17 +++
> include/net/udp.h | 1 +
> include/uapi/asm-generic/socket.h | 2 +
> include/uapi/linux/socket.h | 17 +++
> net/core/skbuff.c | 137 ++++++++++++++++++++++--
> net/core/sock.c | 50 +++++++++
> net/ipv4/ip_output.c | 6 +-
> net/ipv4/tcp.c | 7 +-
> net/ipv4/udp.c | 9 ++
> net/ipv6/ip6_output.c | 5 +-
> net/ipv6/udp.c | 9 ++
> net/vmw_vsock/virtio_transport_common.c | 2 +-
> 16 files changed, 258 insertions(+), 18 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 03ea36a82cdd..19b94ba01007 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -1663,12 +1663,14 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
> #endif
>
> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> - struct ubuf_info *uarg);
> + struct ubuf_info *uarg, bool user_args_notification);
>
> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
>
> void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> bool success);
> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> + bool success);
>
> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
> struct sk_buff *skb, struct iov_iter *from,
> @@ -1763,7 +1765,8 @@ static inline void net_zcopy_put(struct ubuf_info *uarg)
> static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> {
> if (uarg) {
> - if (uarg->callback == msg_zerocopy_callback)
> + if (uarg->callback == msg_zerocopy_callback ||
> + uarg->callback == msg_zerocopy_uarg_callback)
> msg_zerocopy_put_abort(uarg, have_uref);
> else if (have_uref)
> net_zcopy_put(uarg);
> diff --git a/include/linux/socket.h b/include/linux/socket.h
> index 139c330ccf2c..de01392344e1 100644
> --- a/include/linux/socket.h
> +++ b/include/linux/socket.h
> @@ -326,6 +326,7 @@ struct ucred {
> * plain text and require encryption
> */
>
> +#define MSG_ZEROCOPY_UARG 0x2000000 /* MSG_ZEROCOPY with UARG notifications */
> #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
> #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
> #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
> index 55399ee2a57e..e973f4990646 100644
> --- a/include/linux/tcp.h
> +++ b/include/linux/tcp.h
> @@ -501,6 +501,9 @@ struct tcp_sock {
> */
> struct request_sock __rcu *fastopen_rsk;
> struct saved_syn *saved_syn;
> +
> +/* TCP MSG_ZEROCOPY_UARG related information */
> + struct tx_msg_zcopy_queue tx_zcopy_queue;
> };
>
> enum tsq_enum {
> diff --git a/include/linux/udp.h b/include/linux/udp.h
> index 3748e82b627b..502b393eac67 100644
> --- a/include/linux/udp.h
> +++ b/include/linux/udp.h
> @@ -95,6 +95,9 @@ struct udp_sock {
>
> /* Cache friendly copy of sk->sk_peek_off >= 0 */
> bool peeking_with_offset;
> +
> + /* This field is used by sendmsg zcopy user arg mode notification */
> + struct tx_msg_zcopy_queue tx_zcopy_queue;
> };
>
> #define udp_test_bit(nr, sk) \
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 2253eefe2848..f7c045e98213 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -544,6 +544,23 @@ struct sock {
> netns_tracker ns_tracker;
> };
>
> +struct tx_msg_zcopy_node {
> + struct list_head node;
> + struct tx_msg_zcopy_info info;
> + struct sk_buff *skb;
> +};
> +
> +struct tx_msg_zcopy_queue {
> + struct list_head head;
> + spinlock_t lock; /* protects head queue */
> +};
> +
> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
> +{
> + spin_lock_init(&q->lock);
> + INIT_LIST_HEAD(&q->head);
> +}
> +
> enum sk_pacing {
> SK_PACING_NONE = 0,
> SK_PACING_NEEDED = 1,
> diff --git a/include/net/udp.h b/include/net/udp.h
> index 488a6d2babcc..9e4d7b128de4 100644
> --- a/include/net/udp.h
> +++ b/include/net/udp.h
> @@ -182,6 +182,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
> skb_queue_head_init(&up->reader_queue);
> up->forward_threshold = sk->sk_rcvbuf >> 2;
> set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
> + tx_message_zcopy_queue_init(&up->tx_zcopy_queue);
> }
>
> /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
> index 8ce8a39a1e5f..86aa4b5cb7f1 100644
> --- a/include/uapi/asm-generic/socket.h
> +++ b/include/uapi/asm-generic/socket.h
> @@ -135,6 +135,8 @@
> #define SO_PASSPIDFD 76
> #define SO_PEERPIDFD 77
>
> +#define SO_ZEROCOPY_NOTIFICATION 78
> +
> #if !defined(__KERNEL__)
>
> #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
> diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
> index d3fcd3b5ec53..469ed8f4e6c8 100644
> --- a/include/uapi/linux/socket.h
> +++ b/include/uapi/linux/socket.h
> @@ -35,4 +35,21 @@ struct __kernel_sockaddr_storage {
> #define SOCK_TXREHASH_DISABLED 0
> #define SOCK_TXREHASH_ENABLED 1
>
> +/*
> + * Given the fact that MSG_ZEROCOPY_UARG tries to copy notifications
> + * back to user as soon as possible, 8 should be sufficient.
> + */
> +#define SOCK_USR_ZC_INFO_MAX 8
> +
> +struct tx_msg_zcopy_info {
> + __u32 lo;
> + __u32 hi;
> + __u8 zerocopy;
> +};
> +
> +struct tx_usr_zcopy_info {
> + int length;
> + struct tx_msg_zcopy_info info[SOCK_USR_ZC_INFO_MAX];
> +};
> +
> #endif /* _UAPI_LINUX_SOCKET_H */
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 2a5ce6667bbb..d939b2c14d55 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1661,6 +1661,16 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
> }
> EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
>
> +static void init_ubuf_info_msgzc(struct ubuf_info_msgzc *uarg, struct sock *sk, size_t size)
> +{
> + uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
> + uarg->len = 1;
> + uarg->bytelen = size;
> + uarg->zerocopy = 1;
> + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> + refcount_set(&uarg->ubuf.refcnt, 1);
> +}
> +
> static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
> {
> struct ubuf_info_msgzc *uarg;
> @@ -1682,12 +1692,38 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
> }
>
> uarg->ubuf.callback = msg_zerocopy_callback;
> - uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
> - uarg->len = 1;
> - uarg->bytelen = size;
> - uarg->zerocopy = 1;
> - uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> - refcount_set(&uarg->ubuf.refcnt, 1);
> + init_ubuf_info_msgzc(uarg, sk, size);
> + sock_hold(sk);
> +
> + return &uarg->ubuf;
> +}
> +
> +static struct ubuf_info *msg_zerocopy_uarg_alloc(struct sock *sk, size_t size)
> +{
> + struct sk_buff *skb;
> + struct ubuf_info_msgzc *uarg;
> + struct tx_msg_zcopy_node *zcopy_node_p;
> +
> + WARN_ON_ONCE(!in_task());
> +
> + skb = sock_omalloc(sk, sizeof(*zcopy_node_p), GFP_KERNEL);
> + if (!skb)
> + return NULL;
> +
> + BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
> + uarg = (void *)skb->cb;
> + uarg->mmp.user = NULL;
> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb_put(skb, sizeof(*zcopy_node_p));
> +
> + if (mm_account_pinned_pages(&uarg->mmp, size)) {
> + kfree_skb(skb);
> + return NULL;
> + }
> +
> + INIT_LIST_HEAD(&zcopy_node_p->node);
> + zcopy_node_p->skb = skb;
> + uarg->ubuf.callback = msg_zerocopy_uarg_callback;
> + init_ubuf_info_msgzc(uarg, sk, size);
> sock_hold(sk);
>
> return &uarg->ubuf;
> @@ -1699,7 +1735,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
> }
>
> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> - struct ubuf_info *uarg)
> + struct ubuf_info *uarg, bool usr_arg_notification)
> {
> if (uarg) {
> struct ubuf_info_msgzc *uarg_zc;
> @@ -1707,7 +1743,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> u32 bytelen, next;
>
> /* there might be non MSG_ZEROCOPY users */
> - if (uarg->callback != msg_zerocopy_callback)
> + if (uarg->callback != msg_zerocopy_callback &&
> + uarg->callback != msg_zerocopy_uarg_callback)
> return NULL;
>
> /* realloc only when socket is locked (TCP, UDP cork),
> @@ -1744,6 +1781,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> }
>
> new_alloc:
> + if (usr_arg_notification)
> + return msg_zerocopy_uarg_alloc(sk, size);
> return msg_zerocopy_alloc(sk, size);
> }
> EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
> @@ -1830,6 +1869,86 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> }
> EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
>
> +static bool skb_zerocopy_uarg_notify_extend(struct tx_msg_zcopy_node *node, u32 lo, u16 len)
> +{
> + u32 old_lo, old_hi;
> + u64 sum_len;
> +
> + old_lo = node->info.lo;
> + old_hi = node->info.hi;
> + sum_len = old_hi - old_lo + 1ULL + len;
> +
> + if (sum_len >= (1ULL << 32))
> + return false;
> +
> + if (lo != old_hi + 1)
> + return false;
> +
> + node->info.hi += len;
> + return true;
> +}
> +
> +static void __msg_zerocopy_uarg_callback(struct ubuf_info_msgzc *uarg)
> +{
> + struct sk_buff *skb = skb_from_uarg(uarg);
> + struct sock *sk = skb->sk;
> + struct tx_msg_zcopy_node *zcopy_node_p, *tail;
> + struct tx_msg_zcopy_queue *zcopy_queue;
> + unsigned long flags;
> + u32 lo, hi;
> + u16 len;
> +
> + mm_unaccount_pinned_pages(&uarg->mmp);
> +
> + /* if !len, there was only 1 call, and it was aborted
> + * so do not queue a completion notification
> + */
> + if (!uarg->len || sock_flag(sk, SOCK_DEAD))
> + goto release;
> +
> + /* only support TCP and UCP currently */
> + if (sk_is_tcp(sk)) {
> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
> + } else if (sk_is_udp(sk)) {
> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
> + } else {
> + pr_warn("MSG_ZEROCOPY_UARG only support TCP && UDP sockets");
> + goto release;
> + }
> +
> + len = uarg->len;
> + lo = uarg->id;
> + hi = uarg->id + len - 1;
> +
> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb->data;
> + zcopy_node_p->info.lo = lo;
> + zcopy_node_p->info.hi = hi;
> + zcopy_node_p->info.zerocopy = uarg->zerocopy;
> +
> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> + tail = list_last_entry(&zcopy_queue->head, struct tx_msg_zcopy_node, node);
> + if (!tail || !skb_zerocopy_uarg_notify_extend(tail, lo, len)) {
> + list_add_tail(&zcopy_node_p->node, &zcopy_queue->head);
> + skb = NULL;
> + }
> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> +release:
> + consume_skb(skb);
> + sock_put(sk);
> +}
> +
> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> + bool success)
> +{
> + struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
> +
> + uarg_zc->zerocopy = uarg_zc->zerocopy & success;
> +
> + if (refcount_dec_and_test(&uarg->refcnt))
> + __msg_zerocopy_uarg_callback(uarg_zc);
> +}
> +EXPORT_SYMBOL_GPL(msg_zerocopy_uarg_callback);
> +
> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> {
> struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
> @@ -1838,7 +1957,7 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> uarg_to_msgzc(uarg)->len--;
>
> if (have_uref)
> - msg_zerocopy_callback(NULL, uarg, true);
> + uarg->callback(NULL, uarg, true);
> }
> EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
>
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 5ed411231fc7..a00ebd71f6ed 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2843,6 +2843,56 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
> case SCM_RIGHTS:
> case SCM_CREDENTIALS:
> break;
> + case SO_ZEROCOPY_NOTIFICATION:
> + if (sock_flag(sk, SOCK_ZEROCOPY)) {
> + int i = 0;
> + struct tx_usr_zcopy_info sys_zcopy_info;
> + struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
> + struct tx_msg_zcopy_queue *zcopy_queue;
> + struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
> + unsigned long flags;
> +
> + if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
> + return -EINVAL;
> +
> + if (sk_is_tcp(sk))
> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
> + else if (sk_is_udp(sk))
> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
> + else
> + return -EINVAL;
> +
> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> + list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
> + sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
> + sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
> + sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
> + list_del(&zcopy_node_p->node);
> + zcopy_node_ps[i++] = zcopy_node_p;
> + if (i == SOCK_USR_ZC_INFO_MAX)
> + break;
> + }
> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> +
> + if (i > 0) {
> + sys_zcopy_info.length = i;
> + if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
> + &sys_zcopy_info,
> + sizeof(sys_zcopy_info))
> + )) {
> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> + while (i > 0)
> + list_add(&zcopy_node_ps[--i]->node,
> + &zcopy_queue->head);
> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> + return -EFAULT;
> + }
> +
> + while (i > 0)
> + consume_skb(zcopy_node_ps[--i]->skb);
> + }
> + }
> + break;
> default:
> return -EINVAL;
> }
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 1fe794967211..5adb737c4c01 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -1005,7 +1005,7 @@ static int __ip_append_data(struct sock *sk,
> (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
> csummode = CHECKSUM_PARTIAL;
>
> - if ((flags & MSG_ZEROCOPY) && length) {
> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
> struct msghdr *msg = from;
>
> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
> @@ -1022,7 +1022,9 @@ static int __ip_append_data(struct sock *sk,
> uarg = msg->msg_ubuf;
> }
> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
> + bool user_args = flags & MSG_ZEROCOPY_UARG;
> +
> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb), user_args);
> if (!uarg)
> return -ENOBUFS;
> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index e767721b3a58..6254d0eef3af 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -462,6 +462,8 @@ void tcp_init_sock(struct sock *sk)
>
> set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
> sk_sockets_allocated_inc(sk);
> +
> + tx_message_zcopy_queue_init(&tp->tx_zcopy_queue);
> }
> EXPORT_SYMBOL(tcp_init_sock);
>
> @@ -1050,14 +1052,15 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
>
> flags = msg->msg_flags;
>
> - if ((flags & MSG_ZEROCOPY) && size) {
> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && size) {
> if (msg->msg_ubuf) {
> uarg = msg->msg_ubuf;
> if (sk->sk_route_caps & NETIF_F_SG)
> zc = MSG_ZEROCOPY;
> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
> + bool zc_uarg = flags & MSG_ZEROCOPY_UARG;
> skb = tcp_write_queue_tail(sk);
> - uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
> + uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb), zc_uarg);
> if (!uarg) {
> err = -ENOBUFS;
> goto out_err;
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 11460d751e73..6c62aacd74d6 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1126,6 +1126,15 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> if (ipc.opt)
> free = 1;
> connected = 0;
> +
> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
> + * it means this call just wants to get zcopy notifications
> + * instead of sending packets. It is useful when users
> + * finish sending and want to get trailing notifications.
> + */
> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
> + return 0;
> }
> if (!ipc.opt) {
> struct ip_options_rcu *inet_opt;
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index b9dd3a66e423..891526ddd74c 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -1493,7 +1493,7 @@ static int __ip6_append_data(struct sock *sk,
> rt->dst.dev->features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
> csummode = CHECKSUM_PARTIAL;
>
> - if ((flags & MSG_ZEROCOPY) && length) {
> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
> struct msghdr *msg = from;
>
> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
> @@ -1510,7 +1510,8 @@ static int __ip6_append_data(struct sock *sk,
> uarg = msg->msg_ubuf;
> }
> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
> + flags & MSG_ZEROCOPY_UARG);
> if (!uarg)
> return -ENOBUFS;
> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 2e4dc5e6137b..98f6905c5db9 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1490,6 +1490,15 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> if (!(opt->opt_nflen|opt->opt_flen))
> opt = NULL;
> connected = false;
> +
> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
> + * it means this call just wants to get zcopy notifications
> + * instead of sending packets. It is useful when users
> + * finish sending and want to get trailing notifications.
> + */
> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
> + return 0;
> }
> if (!opt) {
> opt = txopt_get(np);
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 16ff976a86e3..d6e6830f6ffe 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -84,7 +84,7 @@ static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
>
> uarg = msg_zerocopy_realloc(sk_vsock(vsk),
> iter->count,
> - NULL);
> + NULL, false);
> if (!uarg)
> return -1;
>
> --
> 2.20.1
>
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [External] Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 21:18 ` Willem de Bruijn
@ 2024-04-10 0:08 ` Zijian Zhang
0 siblings, 0 replies; 24+ messages in thread
From: Zijian Zhang @ 2024-04-10 0:08 UTC (permalink / raw)
To: Willem de Bruijn, netdev; +Cc: edumazet, davem, kuba, cong.wang, xiaochun.lu
On 4/9/24 2:18 PM, Willem de Bruijn wrote:
> zijianzhang@ wrote:
>> From: Zijian Zhang <zijianzhang@bytedance.com>
>>
>> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
>> However, zerocopy is not a free lunch. Apart from the management of user
>> pages, the combination of poll + recvmsg to receive notifications incurs
>> unignorable overhead in the applications. The overhead of such sometimes
>> might be more than the CPU savings from zerocopy. We try to solve this
>> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
>> This new mechanism aims to reduce the overhead associated with receiving
>> notifications by embedding them directly into user arguments passed with
>> each sendmsg control message. By doing so, we can significantly reduce
>> the complexity and overhead for managing notifications. In an ideal
>> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
>> flag, and the notification will be delivered as soon as possible.
>>
>> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
>> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
>
> The idea to avoid POLLERR and errqueue receive cost by piggy-backing
> onto the send() call is appealing.
>
> I also implemented this when initially adding MSG_ZEROCOPY. At the
> time my implementation did not warrant the modest performance
> improvement I measured. But this may be different.
>
> The main reason my code was complex is that this requires changes
> to net/socket.c: controldata is intended to be user->kernel on
> send and kernel->user on recv, such as data. This feature breaks
> that. You'll have to copy msg_controldata in ____sys_sendmsg.
>
> I don't think it requires this much new infrastructure: a separate
> queue in structs tcp_sock and udp_sock, a differente uarg callback.
>
> I would suggest an optimistic algorithm, whereby the send call
> steaks a notification skb from the error queue if present. This
> could be a new mode set with a value 2 in SO_ZEROCOPY.
>
Thanks for the suggestion! I also think that the new infrastructure
requires much code change, it will be nice to reuse the error queue.
And, I agree that the MSG_ZEROCOPY_UARG is not a good name, a new mode
set with a value 2 in SO_ZEROCOPY is a better idea.
I will update in the next patch set.
>> ---
>> include/linux/skbuff.h | 7 +-
>> include/linux/socket.h | 1 +
>> include/linux/tcp.h | 3 +
>> include/linux/udp.h | 3 +
>> include/net/sock.h | 17 +++
>> include/net/udp.h | 1 +
>> include/uapi/asm-generic/socket.h | 2 +
>> include/uapi/linux/socket.h | 17 +++
>> net/core/skbuff.c | 137 ++++++++++++++++++++++--
>> net/core/sock.c | 50 +++++++++
>> net/ipv4/ip_output.c | 6 +-
>> net/ipv4/tcp.c | 7 +-
>> net/ipv4/udp.c | 9 ++
>> net/ipv6/ip6_output.c | 5 +-
>> net/ipv6/udp.c | 9 ++
>> net/vmw_vsock/virtio_transport_common.c | 2 +-
>> 16 files changed, 258 insertions(+), 18 deletions(-)
>>
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index 03ea36a82cdd..19b94ba01007 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -1663,12 +1663,14 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
>> #endif
>>
>> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> - struct ubuf_info *uarg);
>> + struct ubuf_info *uarg, bool user_args_notification);
>>
>> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
>>
>> void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> bool success);
>> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> + bool success);
>>
>> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
>> struct sk_buff *skb, struct iov_iter *from,
>> @@ -1763,7 +1765,8 @@ static inline void net_zcopy_put(struct ubuf_info *uarg)
>> static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>> {
>> if (uarg) {
>> - if (uarg->callback == msg_zerocopy_callback)
>> + if (uarg->callback == msg_zerocopy_callback ||
>> + uarg->callback == msg_zerocopy_uarg_callback)
>> msg_zerocopy_put_abort(uarg, have_uref);
>> else if (have_uref)
>> net_zcopy_put(uarg);
>> diff --git a/include/linux/socket.h b/include/linux/socket.h
>> index 139c330ccf2c..de01392344e1 100644
>> --- a/include/linux/socket.h
>> +++ b/include/linux/socket.h
>> @@ -326,6 +326,7 @@ struct ucred {
>> * plain text and require encryption
>> */
>>
>> +#define MSG_ZEROCOPY_UARG 0x2000000 /* MSG_ZEROCOPY with UARG notifications */
>> #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
>> #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
>> #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
>> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
>> index 55399ee2a57e..e973f4990646 100644
>> --- a/include/linux/tcp.h
>> +++ b/include/linux/tcp.h
>> @@ -501,6 +501,9 @@ struct tcp_sock {
>> */
>> struct request_sock __rcu *fastopen_rsk;
>> struct saved_syn *saved_syn;
>> +
>> +/* TCP MSG_ZEROCOPY_UARG related information */
>> + struct tx_msg_zcopy_queue tx_zcopy_queue;
>> };
>>
>> enum tsq_enum {
>> diff --git a/include/linux/udp.h b/include/linux/udp.h
>> index 3748e82b627b..502b393eac67 100644
>> --- a/include/linux/udp.h
>> +++ b/include/linux/udp.h
>> @@ -95,6 +95,9 @@ struct udp_sock {
>>
>> /* Cache friendly copy of sk->sk_peek_off >= 0 */
>> bool peeking_with_offset;
>> +
>> + /* This field is used by sendmsg zcopy user arg mode notification */
>> + struct tx_msg_zcopy_queue tx_zcopy_queue;
>> };
>>
>> #define udp_test_bit(nr, sk) \
>> diff --git a/include/net/sock.h b/include/net/sock.h
>> index 2253eefe2848..f7c045e98213 100644
>> --- a/include/net/sock.h
>> +++ b/include/net/sock.h
>> @@ -544,6 +544,23 @@ struct sock {
>> netns_tracker ns_tracker;
>> };
>>
>> +struct tx_msg_zcopy_node {
>> + struct list_head node;
>> + struct tx_msg_zcopy_info info;
>> + struct sk_buff *skb;
>> +};
>> +
>> +struct tx_msg_zcopy_queue {
>> + struct list_head head;
>> + spinlock_t lock; /* protects head queue */
>> +};
>> +
>> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
>> +{
>> + spin_lock_init(&q->lock);
>> + INIT_LIST_HEAD(&q->head);
>> +}
>> +
>> enum sk_pacing {
>> SK_PACING_NONE = 0,
>> SK_PACING_NEEDED = 1,
>> diff --git a/include/net/udp.h b/include/net/udp.h
>> index 488a6d2babcc..9e4d7b128de4 100644
>> --- a/include/net/udp.h
>> +++ b/include/net/udp.h
>> @@ -182,6 +182,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
>> skb_queue_head_init(&up->reader_queue);
>> up->forward_threshold = sk->sk_rcvbuf >> 2;
>> set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
>> + tx_message_zcopy_queue_init(&up->tx_zcopy_queue);
>> }
>>
>> /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
>> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
>> index 8ce8a39a1e5f..86aa4b5cb7f1 100644
>> --- a/include/uapi/asm-generic/socket.h
>> +++ b/include/uapi/asm-generic/socket.h
>> @@ -135,6 +135,8 @@
>> #define SO_PASSPIDFD 76
>> #define SO_PEERPIDFD 77
>>
>> +#define SO_ZEROCOPY_NOTIFICATION 78
>> +
>> #if !defined(__KERNEL__)
>>
>> #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
>> diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
>> index d3fcd3b5ec53..469ed8f4e6c8 100644
>> --- a/include/uapi/linux/socket.h
>> +++ b/include/uapi/linux/socket.h
>> @@ -35,4 +35,21 @@ struct __kernel_sockaddr_storage {
>> #define SOCK_TXREHASH_DISABLED 0
>> #define SOCK_TXREHASH_ENABLED 1
>>
>> +/*
>> + * Given the fact that MSG_ZEROCOPY_UARG tries to copy notifications
>> + * back to user as soon as possible, 8 should be sufficient.
>> + */
>> +#define SOCK_USR_ZC_INFO_MAX 8
>> +
>> +struct tx_msg_zcopy_info {
>> + __u32 lo;
>> + __u32 hi;
>> + __u8 zerocopy;
>> +};
>> +
>> +struct tx_usr_zcopy_info {
>> + int length;
>> + struct tx_msg_zcopy_info info[SOCK_USR_ZC_INFO_MAX];
>> +};
>> +
>> #endif /* _UAPI_LINUX_SOCKET_H */
>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
>> index 2a5ce6667bbb..d939b2c14d55 100644
>> --- a/net/core/skbuff.c
>> +++ b/net/core/skbuff.c
>> @@ -1661,6 +1661,16 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
>> }
>> EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
>>
>> +static void init_ubuf_info_msgzc(struct ubuf_info_msgzc *uarg, struct sock *sk, size_t size)
>> +{
>> + uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
>> + uarg->len = 1;
>> + uarg->bytelen = size;
>> + uarg->zerocopy = 1;
>> + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
>> + refcount_set(&uarg->ubuf.refcnt, 1);
>> +}
>> +
>> static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
>> {
>> struct ubuf_info_msgzc *uarg;
>> @@ -1682,12 +1692,38 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
>> }
>>
>> uarg->ubuf.callback = msg_zerocopy_callback;
>> - uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
>> - uarg->len = 1;
>> - uarg->bytelen = size;
>> - uarg->zerocopy = 1;
>> - uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
>> - refcount_set(&uarg->ubuf.refcnt, 1);
>> + init_ubuf_info_msgzc(uarg, sk, size);
>> + sock_hold(sk);
>> +
>> + return &uarg->ubuf;
>> +}
>> +
>> +static struct ubuf_info *msg_zerocopy_uarg_alloc(struct sock *sk, size_t size)
>> +{
>> + struct sk_buff *skb;
>> + struct ubuf_info_msgzc *uarg;
>> + struct tx_msg_zcopy_node *zcopy_node_p;
>> +
>> + WARN_ON_ONCE(!in_task());
>> +
>> + skb = sock_omalloc(sk, sizeof(*zcopy_node_p), GFP_KERNEL);
>> + if (!skb)
>> + return NULL;
>> +
>> + BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
>> + uarg = (void *)skb->cb;
>> + uarg->mmp.user = NULL;
>> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb_put(skb, sizeof(*zcopy_node_p));
>> +
>> + if (mm_account_pinned_pages(&uarg->mmp, size)) {
>> + kfree_skb(skb);
>> + return NULL;
>> + }
>> +
>> + INIT_LIST_HEAD(&zcopy_node_p->node);
>> + zcopy_node_p->skb = skb;
>> + uarg->ubuf.callback = msg_zerocopy_uarg_callback;
>> + init_ubuf_info_msgzc(uarg, sk, size);
>> sock_hold(sk);
>>
>> return &uarg->ubuf;
>> @@ -1699,7 +1735,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
>> }
>>
>> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> - struct ubuf_info *uarg)
>> + struct ubuf_info *uarg, bool usr_arg_notification)
>> {
>> if (uarg) {
>> struct ubuf_info_msgzc *uarg_zc;
>> @@ -1707,7 +1743,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> u32 bytelen, next;
>>
>> /* there might be non MSG_ZEROCOPY users */
>> - if (uarg->callback != msg_zerocopy_callback)
>> + if (uarg->callback != msg_zerocopy_callback &&
>> + uarg->callback != msg_zerocopy_uarg_callback)
>> return NULL;
>>
>> /* realloc only when socket is locked (TCP, UDP cork),
>> @@ -1744,6 +1781,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> }
>>
>> new_alloc:
>> + if (usr_arg_notification)
>> + return msg_zerocopy_uarg_alloc(sk, size);
>> return msg_zerocopy_alloc(sk, size);
>> }
>> EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
>> @@ -1830,6 +1869,86 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> }
>> EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
>>
>> +static bool skb_zerocopy_uarg_notify_extend(struct tx_msg_zcopy_node *node, u32 lo, u16 len)
>> +{
>> + u32 old_lo, old_hi;
>> + u64 sum_len;
>> +
>> + old_lo = node->info.lo;
>> + old_hi = node->info.hi;
>> + sum_len = old_hi - old_lo + 1ULL + len;
>> +
>> + if (sum_len >= (1ULL << 32))
>> + return false;
>> +
>> + if (lo != old_hi + 1)
>> + return false;
>> +
>> + node->info.hi += len;
>> + return true;
>> +}
>> +
>> +static void __msg_zerocopy_uarg_callback(struct ubuf_info_msgzc *uarg)
>> +{
>> + struct sk_buff *skb = skb_from_uarg(uarg);
>> + struct sock *sk = skb->sk;
>> + struct tx_msg_zcopy_node *zcopy_node_p, *tail;
>> + struct tx_msg_zcopy_queue *zcopy_queue;
>> + unsigned long flags;
>> + u32 lo, hi;
>> + u16 len;
>> +
>> + mm_unaccount_pinned_pages(&uarg->mmp);
>> +
>> + /* if !len, there was only 1 call, and it was aborted
>> + * so do not queue a completion notification
>> + */
>> + if (!uarg->len || sock_flag(sk, SOCK_DEAD))
>> + goto release;
>> +
>> + /* only support TCP and UCP currently */
>> + if (sk_is_tcp(sk)) {
>> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
>> + } else if (sk_is_udp(sk)) {
>> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
>> + } else {
>> + pr_warn("MSG_ZEROCOPY_UARG only support TCP && UDP sockets");
>> + goto release;
>> + }
>> +
>> + len = uarg->len;
>> + lo = uarg->id;
>> + hi = uarg->id + len - 1;
>> +
>> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb->data;
>> + zcopy_node_p->info.lo = lo;
>> + zcopy_node_p->info.hi = hi;
>> + zcopy_node_p->info.zerocopy = uarg->zerocopy;
>> +
>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>> + tail = list_last_entry(&zcopy_queue->head, struct tx_msg_zcopy_node, node);
>> + if (!tail || !skb_zerocopy_uarg_notify_extend(tail, lo, len)) {
>> + list_add_tail(&zcopy_node_p->node, &zcopy_queue->head);
>> + skb = NULL;
>> + }
>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>> +release:
>> + consume_skb(skb);
>> + sock_put(sk);
>> +}
>> +
>> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> + bool success)
>> +{
>> + struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
>> +
>> + uarg_zc->zerocopy = uarg_zc->zerocopy & success;
>> +
>> + if (refcount_dec_and_test(&uarg->refcnt))
>> + __msg_zerocopy_uarg_callback(uarg_zc);
>> +}
>> +EXPORT_SYMBOL_GPL(msg_zerocopy_uarg_callback);
>> +
>> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>> {
>> struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
>> @@ -1838,7 +1957,7 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>> uarg_to_msgzc(uarg)->len--;
>>
>> if (have_uref)
>> - msg_zerocopy_callback(NULL, uarg, true);
>> + uarg->callback(NULL, uarg, true);
>> }
>> EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
>>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index 5ed411231fc7..a00ebd71f6ed 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -2843,6 +2843,56 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
>> case SCM_RIGHTS:
>> case SCM_CREDENTIALS:
>> break;
>> + case SO_ZEROCOPY_NOTIFICATION:
>> + if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> + int i = 0;
>> + struct tx_usr_zcopy_info sys_zcopy_info;
>> + struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
>> + struct tx_msg_zcopy_queue *zcopy_queue;
>> + struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
>> + unsigned long flags;
>> +
>> + if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
>> + return -EINVAL;
>> +
>> + if (sk_is_tcp(sk))
>> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
>> + else if (sk_is_udp(sk))
>> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
>> + else
>> + return -EINVAL;
>> +
>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>> + list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
>> + sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
>> + sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
>> + sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
>> + list_del(&zcopy_node_p->node);
>> + zcopy_node_ps[i++] = zcopy_node_p;
>> + if (i == SOCK_USR_ZC_INFO_MAX)
>> + break;
>> + }
>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>> +
>> + if (i > 0) {
>> + sys_zcopy_info.length = i;
>> + if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
>> + &sys_zcopy_info,
>> + sizeof(sys_zcopy_info))
>> + )) {
>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>> + while (i > 0)
>> + list_add(&zcopy_node_ps[--i]->node,
>> + &zcopy_queue->head);
>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>> + return -EFAULT;
>> + }
>> +
>> + while (i > 0)
>> + consume_skb(zcopy_node_ps[--i]->skb);
>> + }
>> + }
>> + break;
>> default:
>> return -EINVAL;
>> }
>> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
>> index 1fe794967211..5adb737c4c01 100644
>> --- a/net/ipv4/ip_output.c
>> +++ b/net/ipv4/ip_output.c
>> @@ -1005,7 +1005,7 @@ static int __ip_append_data(struct sock *sk,
>> (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
>> csummode = CHECKSUM_PARTIAL;
>>
>> - if ((flags & MSG_ZEROCOPY) && length) {
>> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
>> struct msghdr *msg = from;
>>
>> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
>> @@ -1022,7 +1022,9 @@ static int __ip_append_data(struct sock *sk,
>> uarg = msg->msg_ubuf;
>> }
>> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
>> + bool user_args = flags & MSG_ZEROCOPY_UARG;
>> +
>> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb), user_args);
>> if (!uarg)
>> return -ENOBUFS;
>> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>> index e767721b3a58..6254d0eef3af 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -462,6 +462,8 @@ void tcp_init_sock(struct sock *sk)
>>
>> set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
>> sk_sockets_allocated_inc(sk);
>> +
>> + tx_message_zcopy_queue_init(&tp->tx_zcopy_queue);
>> }
>> EXPORT_SYMBOL(tcp_init_sock);
>>
>> @@ -1050,14 +1052,15 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
>>
>> flags = msg->msg_flags;
>>
>> - if ((flags & MSG_ZEROCOPY) && size) {
>> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && size) {
>> if (msg->msg_ubuf) {
>> uarg = msg->msg_ubuf;
>> if (sk->sk_route_caps & NETIF_F_SG)
>> zc = MSG_ZEROCOPY;
>> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> + bool zc_uarg = flags & MSG_ZEROCOPY_UARG;
>> skb = tcp_write_queue_tail(sk);
>> - uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
>> + uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb), zc_uarg);
>> if (!uarg) {
>> err = -ENOBUFS;
>> goto out_err;
>> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
>> index 11460d751e73..6c62aacd74d6 100644
>> --- a/net/ipv4/udp.c
>> +++ b/net/ipv4/udp.c
>> @@ -1126,6 +1126,15 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>> if (ipc.opt)
>> free = 1;
>> connected = 0;
>> +
>> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
>> + * it means this call just wants to get zcopy notifications
>> + * instead of sending packets. It is useful when users
>> + * finish sending and want to get trailing notifications.
>> + */
>> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
>> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
>> + return 0;
>> }
>> if (!ipc.opt) {
>> struct ip_options_rcu *inet_opt;
>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
>> index b9dd3a66e423..891526ddd74c 100644
>> --- a/net/ipv6/ip6_output.c
>> +++ b/net/ipv6/ip6_output.c
>> @@ -1493,7 +1493,7 @@ static int __ip6_append_data(struct sock *sk,
>> rt->dst.dev->features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
>> csummode = CHECKSUM_PARTIAL;
>>
>> - if ((flags & MSG_ZEROCOPY) && length) {
>> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
>> struct msghdr *msg = from;
>>
>> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
>> @@ -1510,7 +1510,8 @@ static int __ip6_append_data(struct sock *sk,
>> uarg = msg->msg_ubuf;
>> }
>> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
>> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
>> + flags & MSG_ZEROCOPY_UARG);
>> if (!uarg)
>> return -ENOBUFS;
>> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
>> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
>> index 2e4dc5e6137b..98f6905c5db9 100644
>> --- a/net/ipv6/udp.c
>> +++ b/net/ipv6/udp.c
>> @@ -1490,6 +1490,15 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>> if (!(opt->opt_nflen|opt->opt_flen))
>> opt = NULL;
>> connected = false;
>> +
>> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
>> + * it means this call just wants to get zcopy notifications
>> + * instead of sending packets. It is useful when users
>> + * finish sending and want to get trailing notifications.
>> + */
>> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
>> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
>> + return 0;
>> }
>> if (!opt) {
>> opt = txopt_get(np);
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index 16ff976a86e3..d6e6830f6ffe 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -84,7 +84,7 @@ static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
>>
>> uarg = msg_zerocopy_realloc(sk_vsock(vsk),
>> iter->count,
>> - NULL);
>> + NULL, false);
>> if (!uarg)
>> return -1;
>>
>> --
>> 2.20.1
>>
>
>
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 20:52 ` [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG zijianzhang
2024-04-09 21:18 ` Willem de Bruijn
@ 2024-04-09 21:18 ` Eric Dumazet
2024-04-10 17:01 ` [External] " Zijian Zhang
2024-04-09 21:23 ` Eric Dumazet
` (3 subsequent siblings)
5 siblings, 1 reply; 24+ messages in thread
From: Eric Dumazet @ 2024-04-09 21:18 UTC (permalink / raw)
To: zijianzhang
Cc: netdev, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu
On Tue, Apr 9, 2024 at 10:53 PM <zijianzhang@bytedance.com> wrote:
>
> From: Zijian Zhang <zijianzhang@bytedance.com>
>
> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
> However, zerocopy is not a free lunch. Apart from the management of user
> pages, the combination of poll + recvmsg to receive notifications incurs
> unignorable overhead in the applications. The overhead of such sometimes
> might be more than the CPU savings from zerocopy. We try to solve this
> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
> This new mechanism aims to reduce the overhead associated with receiving
> notifications by embedding them directly into user arguments passed with
> each sendmsg control message. By doing so, we can significantly reduce
> the complexity and overhead for managing notifications. In an ideal
> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
> flag, and the notification will be delivered as soon as possible.
>
> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
> ---
> include/linux/skbuff.h | 7 +-
> include/linux/socket.h | 1 +
> include/linux/tcp.h | 3 +
> include/linux/udp.h | 3 +
> include/net/sock.h | 17 +++
> include/net/udp.h | 1 +
> include/uapi/asm-generic/socket.h | 2 +
> include/uapi/linux/socket.h | 17 +++
> net/core/skbuff.c | 137 ++++++++++++++++++++++--
> net/core/sock.c | 50 +++++++++
> net/ipv4/ip_output.c | 6 +-
> net/ipv4/tcp.c | 7 +-
> net/ipv4/udp.c | 9 ++
> net/ipv6/ip6_output.c | 5 +-
> net/ipv6/udp.c | 9 ++
> net/vmw_vsock/virtio_transport_common.c | 2 +-
> 16 files changed, 258 insertions(+), 18 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 03ea36a82cdd..19b94ba01007 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -1663,12 +1663,14 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
> #endif
>
> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> - struct ubuf_info *uarg);
> + struct ubuf_info *uarg, bool user_args_notification);
>
> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
>
> void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> bool success);
> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> + bool success);
>
> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
> struct sk_buff *skb, struct iov_iter *from,
> @@ -1763,7 +1765,8 @@ static inline void net_zcopy_put(struct ubuf_info *uarg)
> static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> {
> if (uarg) {
> - if (uarg->callback == msg_zerocopy_callback)
> + if (uarg->callback == msg_zerocopy_callback ||
> + uarg->callback == msg_zerocopy_uarg_callback)
> msg_zerocopy_put_abort(uarg, have_uref);
> else if (have_uref)
> net_zcopy_put(uarg);
> diff --git a/include/linux/socket.h b/include/linux/socket.h
> index 139c330ccf2c..de01392344e1 100644
> --- a/include/linux/socket.h
> +++ b/include/linux/socket.h
> @@ -326,6 +326,7 @@ struct ucred {
> * plain text and require encryption
> */
>
> +#define MSG_ZEROCOPY_UARG 0x2000000 /* MSG_ZEROCOPY with UARG notifications */
> #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
> #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
> #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
> index 55399ee2a57e..e973f4990646 100644
> --- a/include/linux/tcp.h
> +++ b/include/linux/tcp.h
> @@ -501,6 +501,9 @@ struct tcp_sock {
> */
> struct request_sock __rcu *fastopen_rsk;
> struct saved_syn *saved_syn;
> +
> +/* TCP MSG_ZEROCOPY_UARG related information */
> + struct tx_msg_zcopy_queue tx_zcopy_queue;
> };
>
> enum tsq_enum {
> diff --git a/include/linux/udp.h b/include/linux/udp.h
> index 3748e82b627b..502b393eac67 100644
> --- a/include/linux/udp.h
> +++ b/include/linux/udp.h
> @@ -95,6 +95,9 @@ struct udp_sock {
>
> /* Cache friendly copy of sk->sk_peek_off >= 0 */
> bool peeking_with_offset;
> +
> + /* This field is used by sendmsg zcopy user arg mode notification */
> + struct tx_msg_zcopy_queue tx_zcopy_queue;
> };
>
> #define udp_test_bit(nr, sk) \
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 2253eefe2848..f7c045e98213 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -544,6 +544,23 @@ struct sock {
> netns_tracker ns_tracker;
> };
>
> +struct tx_msg_zcopy_node {
> + struct list_head node;
> + struct tx_msg_zcopy_info info;
> + struct sk_buff *skb;
> +};
> +
> +struct tx_msg_zcopy_queue {
> + struct list_head head;
> + spinlock_t lock; /* protects head queue */
> +};
> +
> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
> +{
> + spin_lock_init(&q->lock);
> + INIT_LIST_HEAD(&q->head);
> +}
> +
> enum sk_pacing {
> SK_PACING_NONE = 0,
> SK_PACING_NEEDED = 1,
> diff --git a/include/net/udp.h b/include/net/udp.h
> index 488a6d2babcc..9e4d7b128de4 100644
> --- a/include/net/udp.h
> +++ b/include/net/udp.h
> @@ -182,6 +182,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
> skb_queue_head_init(&up->reader_queue);
> up->forward_threshold = sk->sk_rcvbuf >> 2;
> set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
> + tx_message_zcopy_queue_init(&up->tx_zcopy_queue);
> }
>
> /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
> index 8ce8a39a1e5f..86aa4b5cb7f1 100644
> --- a/include/uapi/asm-generic/socket.h
> +++ b/include/uapi/asm-generic/socket.h
> @@ -135,6 +135,8 @@
> #define SO_PASSPIDFD 76
> #define SO_PEERPIDFD 77
>
> +#define SO_ZEROCOPY_NOTIFICATION 78
> +
> #if !defined(__KERNEL__)
>
> #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
> diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
> index d3fcd3b5ec53..469ed8f4e6c8 100644
> --- a/include/uapi/linux/socket.h
> +++ b/include/uapi/linux/socket.h
> @@ -35,4 +35,21 @@ struct __kernel_sockaddr_storage {
> #define SOCK_TXREHASH_DISABLED 0
> #define SOCK_TXREHASH_ENABLED 1
>
> +/*
> + * Given the fact that MSG_ZEROCOPY_UARG tries to copy notifications
> + * back to user as soon as possible, 8 should be sufficient.
> + */
> +#define SOCK_USR_ZC_INFO_MAX 8
> +
> +struct tx_msg_zcopy_info {
> + __u32 lo;
> + __u32 hi;
> + __u8 zerocopy;
> +};
> +
> +struct tx_usr_zcopy_info {
> + int length;
> + struct tx_msg_zcopy_info info[SOCK_USR_ZC_INFO_MAX];
> +};
> +
> #endif /* _UAPI_LINUX_SOCKET_H */
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 2a5ce6667bbb..d939b2c14d55 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1661,6 +1661,16 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
> }
> EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
>
> +static void init_ubuf_info_msgzc(struct ubuf_info_msgzc *uarg, struct sock *sk, size_t size)
> +{
> + uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
> + uarg->len = 1;
> + uarg->bytelen = size;
> + uarg->zerocopy = 1;
> + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> + refcount_set(&uarg->ubuf.refcnt, 1);
> +}
> +
> static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
> {
> struct ubuf_info_msgzc *uarg;
> @@ -1682,12 +1692,38 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
> }
>
> uarg->ubuf.callback = msg_zerocopy_callback;
> - uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
> - uarg->len = 1;
> - uarg->bytelen = size;
> - uarg->zerocopy = 1;
> - uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> - refcount_set(&uarg->ubuf.refcnt, 1);
> + init_ubuf_info_msgzc(uarg, sk, size);
> + sock_hold(sk);
> +
> + return &uarg->ubuf;
> +}
> +
> +static struct ubuf_info *msg_zerocopy_uarg_alloc(struct sock *sk, size_t size)
> +{
> + struct sk_buff *skb;
> + struct ubuf_info_msgzc *uarg;
> + struct tx_msg_zcopy_node *zcopy_node_p;
> +
> + WARN_ON_ONCE(!in_task());
> +
> + skb = sock_omalloc(sk, sizeof(*zcopy_node_p), GFP_KERNEL);
> + if (!skb)
> + return NULL;
> +
> + BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
> + uarg = (void *)skb->cb;
> + uarg->mmp.user = NULL;
> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb_put(skb, sizeof(*zcopy_node_p));
> +
> + if (mm_account_pinned_pages(&uarg->mmp, size)) {
> + kfree_skb(skb);
> + return NULL;
> + }
> +
> + INIT_LIST_HEAD(&zcopy_node_p->node);
> + zcopy_node_p->skb = skb;
> + uarg->ubuf.callback = msg_zerocopy_uarg_callback;
> + init_ubuf_info_msgzc(uarg, sk, size);
> sock_hold(sk);
>
> return &uarg->ubuf;
> @@ -1699,7 +1735,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
> }
>
> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> - struct ubuf_info *uarg)
> + struct ubuf_info *uarg, bool usr_arg_notification)
> {
> if (uarg) {
> struct ubuf_info_msgzc *uarg_zc;
> @@ -1707,7 +1743,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> u32 bytelen, next;
>
> /* there might be non MSG_ZEROCOPY users */
> - if (uarg->callback != msg_zerocopy_callback)
> + if (uarg->callback != msg_zerocopy_callback &&
> + uarg->callback != msg_zerocopy_uarg_callback)
> return NULL;
>
> /* realloc only when socket is locked (TCP, UDP cork),
> @@ -1744,6 +1781,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> }
>
> new_alloc:
> + if (usr_arg_notification)
> + return msg_zerocopy_uarg_alloc(sk, size);
> return msg_zerocopy_alloc(sk, size);
> }
> EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
> @@ -1830,6 +1869,86 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> }
> EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
>
> +static bool skb_zerocopy_uarg_notify_extend(struct tx_msg_zcopy_node *node, u32 lo, u16 len)
> +{
> + u32 old_lo, old_hi;
> + u64 sum_len;
> +
> + old_lo = node->info.lo;
> + old_hi = node->info.hi;
> + sum_len = old_hi - old_lo + 1ULL + len;
> +
> + if (sum_len >= (1ULL << 32))
> + return false;
> +
> + if (lo != old_hi + 1)
> + return false;
> +
> + node->info.hi += len;
> + return true;
> +}
> +
> +static void __msg_zerocopy_uarg_callback(struct ubuf_info_msgzc *uarg)
> +{
> + struct sk_buff *skb = skb_from_uarg(uarg);
> + struct sock *sk = skb->sk;
> + struct tx_msg_zcopy_node *zcopy_node_p, *tail;
> + struct tx_msg_zcopy_queue *zcopy_queue;
> + unsigned long flags;
> + u32 lo, hi;
> + u16 len;
> +
> + mm_unaccount_pinned_pages(&uarg->mmp);
> +
> + /* if !len, there was only 1 call, and it was aborted
> + * so do not queue a completion notification
> + */
> + if (!uarg->len || sock_flag(sk, SOCK_DEAD))
> + goto release;
> +
> + /* only support TCP and UCP currently */
> + if (sk_is_tcp(sk)) {
> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
> + } else if (sk_is_udp(sk)) {
> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
> + } else {
> + pr_warn("MSG_ZEROCOPY_UARG only support TCP && UDP sockets");
> + goto release;
> + }
> +
> + len = uarg->len;
> + lo = uarg->id;
> + hi = uarg->id + len - 1;
> +
> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb->data;
> + zcopy_node_p->info.lo = lo;
> + zcopy_node_p->info.hi = hi;
> + zcopy_node_p->info.zerocopy = uarg->zerocopy;
> +
> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> + tail = list_last_entry(&zcopy_queue->head, struct tx_msg_zcopy_node, node);
> + if (!tail || !skb_zerocopy_uarg_notify_extend(tail, lo, len)) {
> + list_add_tail(&zcopy_node_p->node, &zcopy_queue->head);
> + skb = NULL;
> + }
> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> +release:
> + consume_skb(skb);
> + sock_put(sk);
> +}
> +
> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> + bool success)
> +{
> + struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
> +
> + uarg_zc->zerocopy = uarg_zc->zerocopy & success;
> +
> + if (refcount_dec_and_test(&uarg->refcnt))
> + __msg_zerocopy_uarg_callback(uarg_zc);
> +}
> +EXPORT_SYMBOL_GPL(msg_zerocopy_uarg_callback);
> +
> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> {
> struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
> @@ -1838,7 +1957,7 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> uarg_to_msgzc(uarg)->len--;
>
> if (have_uref)
> - msg_zerocopy_callback(NULL, uarg, true);
> + uarg->callback(NULL, uarg, true);
> }
> EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
>
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 5ed411231fc7..a00ebd71f6ed 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2843,6 +2843,56 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
> case SCM_RIGHTS:
> case SCM_CREDENTIALS:
> break;
> + case SO_ZEROCOPY_NOTIFICATION:
> + if (sock_flag(sk, SOCK_ZEROCOPY)) {
> + int i = 0;
> + struct tx_usr_zcopy_info sys_zcopy_info;
> + struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
> + struct tx_msg_zcopy_queue *zcopy_queue;
> + struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
> + unsigned long flags;
> +
> + if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
> + return -EINVAL;
> +
> + if (sk_is_tcp(sk))
> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
> + else if (sk_is_udp(sk))
> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
> + else
> + return -EINVAL;
> +
> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> + list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
> + sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
> + sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
> + sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
> + list_del(&zcopy_node_p->node);
> + zcopy_node_ps[i++] = zcopy_node_p;
> + if (i == SOCK_USR_ZC_INFO_MAX)
> + break;
> + }
> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> +
> + if (i > 0) {
> + sys_zcopy_info.length = i;
> + if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
This is going to break if user space is 32bit, and kernel 64bit ?
Also SOCK_USR_ZC_INFO_MAX is put in stone, it won't change in the future.
> + &sys_zcopy_info,
> + sizeof(sys_zcopy_info))
Your are leaking to user space part of kernel stack, if (i <
SOCK_USR_ZC_INFO_MAX)
> + )) {
> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> + while (i > 0)
> + list_add(&zcopy_node_ps[--i]->node,
> + &zcopy_queue->head);
> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> + return -EFAULT;
> + }
> +
> + while (i > 0)
> + consume_skb(zcopy_node_ps[--i]->skb);
> + }
> + }
> + break;
> default:
> return -EINVAL;
> }
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 1fe794967211..5adb737c4c01 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -1005,7 +1005,7 @@ static int __ip_append_data(struct sock *sk,
> (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
> csummode = CHECKSUM_PARTIAL;
>
> - if ((flags & MSG_ZEROCOPY) && length) {
> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
> struct msghdr *msg = from;
>
> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
> @@ -1022,7 +1022,9 @@ static int __ip_append_data(struct sock *sk,
> uarg = msg->msg_ubuf;
> }
> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
> + bool user_args = flags & MSG_ZEROCOPY_UARG;
> +
> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb), user_args);
> if (!uarg)
> return -ENOBUFS;
> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index e767721b3a58..6254d0eef3af 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -462,6 +462,8 @@ void tcp_init_sock(struct sock *sk)
>
> set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
> sk_sockets_allocated_inc(sk);
> +
> + tx_message_zcopy_queue_init(&tp->tx_zcopy_queue);
> }
> EXPORT_SYMBOL(tcp_init_sock);
>
> @@ -1050,14 +1052,15 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
>
> flags = msg->msg_flags;
>
> - if ((flags & MSG_ZEROCOPY) && size) {
> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && size) {
> if (msg->msg_ubuf) {
> uarg = msg->msg_ubuf;
> if (sk->sk_route_caps & NETIF_F_SG)
> zc = MSG_ZEROCOPY;
> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
> + bool zc_uarg = flags & MSG_ZEROCOPY_UARG;
> skb = tcp_write_queue_tail(sk);
> - uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
> + uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb), zc_uarg);
> if (!uarg) {
> err = -ENOBUFS;
> goto out_err;
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 11460d751e73..6c62aacd74d6 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1126,6 +1126,15 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> if (ipc.opt)
> free = 1;
> connected = 0;
> +
> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
> + * it means this call just wants to get zcopy notifications
> + * instead of sending packets. It is useful when users
> + * finish sending and want to get trailing notifications.
> + */
> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
> + return 0;
> }
> if (!ipc.opt) {
> struct ip_options_rcu *inet_opt;
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index b9dd3a66e423..891526ddd74c 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -1493,7 +1493,7 @@ static int __ip6_append_data(struct sock *sk,
> rt->dst.dev->features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
> csummode = CHECKSUM_PARTIAL;
>
> - if ((flags & MSG_ZEROCOPY) && length) {
> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
> struct msghdr *msg = from;
>
> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
> @@ -1510,7 +1510,8 @@ static int __ip6_append_data(struct sock *sk,
> uarg = msg->msg_ubuf;
> }
> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
> + flags & MSG_ZEROCOPY_UARG);
> if (!uarg)
> return -ENOBUFS;
> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 2e4dc5e6137b..98f6905c5db9 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1490,6 +1490,15 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
> if (!(opt->opt_nflen|opt->opt_flen))
> opt = NULL;
> connected = false;
> +
> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
> + * it means this call just wants to get zcopy notifications
> + * instead of sending packets. It is useful when users
> + * finish sending and want to get trailing notifications.
> + */
> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
> + return 0;
> }
> if (!opt) {
> opt = txopt_get(np);
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 16ff976a86e3..d6e6830f6ffe 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -84,7 +84,7 @@ static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
>
> uarg = msg_zerocopy_realloc(sk_vsock(vsk),
> iter->count,
> - NULL);
> + NULL, false);
> if (!uarg)
> return -1;
>
> --
> 2.20.1
>
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [External] Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 21:18 ` Eric Dumazet
@ 2024-04-10 17:01 ` Zijian Zhang
2024-04-10 18:57 ` Eric Dumazet
0 siblings, 1 reply; 24+ messages in thread
From: Zijian Zhang @ 2024-04-10 17:01 UTC (permalink / raw)
To: Eric Dumazet
Cc: netdev, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu
On 4/9/24 2:18 PM, Eric Dumazet wrote:
> On Tue, Apr 9, 2024 at 10:53 PM <zijianzhang@bytedance.com> wrote:
>>
>> From: Zijian Zhang <zijianzhang@bytedance.com>
>>
>> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
>> However, zerocopy is not a free lunch. Apart from the management of user
>> pages, the combination of poll + recvmsg to receive notifications incurs
>> unignorable overhead in the applications. The overhead of such sometimes
>> might be more than the CPU savings from zerocopy. We try to solve this
>> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
>> This new mechanism aims to reduce the overhead associated with receiving
>> notifications by embedding them directly into user arguments passed with
>> each sendmsg control message. By doing so, we can significantly reduce
>> the complexity and overhead for managing notifications. In an ideal
>> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
>> flag, and the notification will be delivered as soon as possible.
>>
>> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
>> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
>> ---
>> include/linux/skbuff.h | 7 +-
>> include/linux/socket.h | 1 +
>> include/linux/tcp.h | 3 +
>> include/linux/udp.h | 3 +
>> include/net/sock.h | 17 +++
>> include/net/udp.h | 1 +
>> include/uapi/asm-generic/socket.h | 2 +
>> include/uapi/linux/socket.h | 17 +++
>> net/core/skbuff.c | 137 ++++++++++++++++++++++--
>> net/core/sock.c | 50 +++++++++
>> net/ipv4/ip_output.c | 6 +-
>> net/ipv4/tcp.c | 7 +-
>> net/ipv4/udp.c | 9 ++
>> net/ipv6/ip6_output.c | 5 +-
>> net/ipv6/udp.c | 9 ++
>> net/vmw_vsock/virtio_transport_common.c | 2 +-
>> 16 files changed, 258 insertions(+), 18 deletions(-)
>>
>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>> index 03ea36a82cdd..19b94ba01007 100644
>> --- a/include/linux/skbuff.h
>> +++ b/include/linux/skbuff.h
>> @@ -1663,12 +1663,14 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
>> #endif
>>
>> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> - struct ubuf_info *uarg);
>> + struct ubuf_info *uarg, bool user_args_notification);
>>
>> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
>>
>> void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> bool success);
>> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> + bool success);
>>
>> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
>> struct sk_buff *skb, struct iov_iter *from,
>> @@ -1763,7 +1765,8 @@ static inline void net_zcopy_put(struct ubuf_info *uarg)
>> static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>> {
>> if (uarg) {
>> - if (uarg->callback == msg_zerocopy_callback)
>> + if (uarg->callback == msg_zerocopy_callback ||
>> + uarg->callback == msg_zerocopy_uarg_callback)
>> msg_zerocopy_put_abort(uarg, have_uref);
>> else if (have_uref)
>> net_zcopy_put(uarg);
>> diff --git a/include/linux/socket.h b/include/linux/socket.h
>> index 139c330ccf2c..de01392344e1 100644
>> --- a/include/linux/socket.h
>> +++ b/include/linux/socket.h
>> @@ -326,6 +326,7 @@ struct ucred {
>> * plain text and require encryption
>> */
>>
>> +#define MSG_ZEROCOPY_UARG 0x2000000 /* MSG_ZEROCOPY with UARG notifications */
>> #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
>> #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
>> #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
>> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
>> index 55399ee2a57e..e973f4990646 100644
>> --- a/include/linux/tcp.h
>> +++ b/include/linux/tcp.h
>> @@ -501,6 +501,9 @@ struct tcp_sock {
>> */
>> struct request_sock __rcu *fastopen_rsk;
>> struct saved_syn *saved_syn;
>> +
>> +/* TCP MSG_ZEROCOPY_UARG related information */
>> + struct tx_msg_zcopy_queue tx_zcopy_queue;
>> };
>>
>> enum tsq_enum {
>> diff --git a/include/linux/udp.h b/include/linux/udp.h
>> index 3748e82b627b..502b393eac67 100644
>> --- a/include/linux/udp.h
>> +++ b/include/linux/udp.h
>> @@ -95,6 +95,9 @@ struct udp_sock {
>>
>> /* Cache friendly copy of sk->sk_peek_off >= 0 */
>> bool peeking_with_offset;
>> +
>> + /* This field is used by sendmsg zcopy user arg mode notification */
>> + struct tx_msg_zcopy_queue tx_zcopy_queue;
>> };
>>
>> #define udp_test_bit(nr, sk) \
>> diff --git a/include/net/sock.h b/include/net/sock.h
>> index 2253eefe2848..f7c045e98213 100644
>> --- a/include/net/sock.h
>> +++ b/include/net/sock.h
>> @@ -544,6 +544,23 @@ struct sock {
>> netns_tracker ns_tracker;
>> };
>>
>> +struct tx_msg_zcopy_node {
>> + struct list_head node;
>> + struct tx_msg_zcopy_info info;
>> + struct sk_buff *skb;
>> +};
>> +
>> +struct tx_msg_zcopy_queue {
>> + struct list_head head;
>> + spinlock_t lock; /* protects head queue */
>> +};
>> +
>> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
>> +{
>> + spin_lock_init(&q->lock);
>> + INIT_LIST_HEAD(&q->head);
>> +}
>> +
>> enum sk_pacing {
>> SK_PACING_NONE = 0,
>> SK_PACING_NEEDED = 1,
>> diff --git a/include/net/udp.h b/include/net/udp.h
>> index 488a6d2babcc..9e4d7b128de4 100644
>> --- a/include/net/udp.h
>> +++ b/include/net/udp.h
>> @@ -182,6 +182,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
>> skb_queue_head_init(&up->reader_queue);
>> up->forward_threshold = sk->sk_rcvbuf >> 2;
>> set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
>> + tx_message_zcopy_queue_init(&up->tx_zcopy_queue);
>> }
>>
>> /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
>> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
>> index 8ce8a39a1e5f..86aa4b5cb7f1 100644
>> --- a/include/uapi/asm-generic/socket.h
>> +++ b/include/uapi/asm-generic/socket.h
>> @@ -135,6 +135,8 @@
>> #define SO_PASSPIDFD 76
>> #define SO_PEERPIDFD 77
>>
>> +#define SO_ZEROCOPY_NOTIFICATION 78
>> +
>> #if !defined(__KERNEL__)
>>
>> #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
>> diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
>> index d3fcd3b5ec53..469ed8f4e6c8 100644
>> --- a/include/uapi/linux/socket.h
>> +++ b/include/uapi/linux/socket.h
>> @@ -35,4 +35,21 @@ struct __kernel_sockaddr_storage {
>> #define SOCK_TXREHASH_DISABLED 0
>> #define SOCK_TXREHASH_ENABLED 1
>>
>> +/*
>> + * Given the fact that MSG_ZEROCOPY_UARG tries to copy notifications
>> + * back to user as soon as possible, 8 should be sufficient.
>> + */
>> +#define SOCK_USR_ZC_INFO_MAX 8
>> +
>> +struct tx_msg_zcopy_info {
>> + __u32 lo;
>> + __u32 hi;
>> + __u8 zerocopy;
>> +};
>> +
>> +struct tx_usr_zcopy_info {
>> + int length;
>> + struct tx_msg_zcopy_info info[SOCK_USR_ZC_INFO_MAX];
>> +};
>> +
>> #endif /* _UAPI_LINUX_SOCKET_H */
>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
>> index 2a5ce6667bbb..d939b2c14d55 100644
>> --- a/net/core/skbuff.c
>> +++ b/net/core/skbuff.c
>> @@ -1661,6 +1661,16 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
>> }
>> EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
>>
>> +static void init_ubuf_info_msgzc(struct ubuf_info_msgzc *uarg, struct sock *sk, size_t size)
>> +{
>> + uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
>> + uarg->len = 1;
>> + uarg->bytelen = size;
>> + uarg->zerocopy = 1;
>> + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
>> + refcount_set(&uarg->ubuf.refcnt, 1);
>> +}
>> +
>> static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
>> {
>> struct ubuf_info_msgzc *uarg;
>> @@ -1682,12 +1692,38 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
>> }
>>
>> uarg->ubuf.callback = msg_zerocopy_callback;
>> - uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
>> - uarg->len = 1;
>> - uarg->bytelen = size;
>> - uarg->zerocopy = 1;
>> - uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
>> - refcount_set(&uarg->ubuf.refcnt, 1);
>> + init_ubuf_info_msgzc(uarg, sk, size);
>> + sock_hold(sk);
>> +
>> + return &uarg->ubuf;
>> +}
>> +
>> +static struct ubuf_info *msg_zerocopy_uarg_alloc(struct sock *sk, size_t size)
>> +{
>> + struct sk_buff *skb;
>> + struct ubuf_info_msgzc *uarg;
>> + struct tx_msg_zcopy_node *zcopy_node_p;
>> +
>> + WARN_ON_ONCE(!in_task());
>> +
>> + skb = sock_omalloc(sk, sizeof(*zcopy_node_p), GFP_KERNEL);
>> + if (!skb)
>> + return NULL;
>> +
>> + BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
>> + uarg = (void *)skb->cb;
>> + uarg->mmp.user = NULL;
>> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb_put(skb, sizeof(*zcopy_node_p));
>> +
>> + if (mm_account_pinned_pages(&uarg->mmp, size)) {
>> + kfree_skb(skb);
>> + return NULL;
>> + }
>> +
>> + INIT_LIST_HEAD(&zcopy_node_p->node);
>> + zcopy_node_p->skb = skb;
>> + uarg->ubuf.callback = msg_zerocopy_uarg_callback;
>> + init_ubuf_info_msgzc(uarg, sk, size);
>> sock_hold(sk);
>>
>> return &uarg->ubuf;
>> @@ -1699,7 +1735,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
>> }
>>
>> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> - struct ubuf_info *uarg)
>> + struct ubuf_info *uarg, bool usr_arg_notification)
>> {
>> if (uarg) {
>> struct ubuf_info_msgzc *uarg_zc;
>> @@ -1707,7 +1743,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> u32 bytelen, next;
>>
>> /* there might be non MSG_ZEROCOPY users */
>> - if (uarg->callback != msg_zerocopy_callback)
>> + if (uarg->callback != msg_zerocopy_callback &&
>> + uarg->callback != msg_zerocopy_uarg_callback)
>> return NULL;
>>
>> /* realloc only when socket is locked (TCP, UDP cork),
>> @@ -1744,6 +1781,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>> }
>>
>> new_alloc:
>> + if (usr_arg_notification)
>> + return msg_zerocopy_uarg_alloc(sk, size);
>> return msg_zerocopy_alloc(sk, size);
>> }
>> EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
>> @@ -1830,6 +1869,86 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> }
>> EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
>>
>> +static bool skb_zerocopy_uarg_notify_extend(struct tx_msg_zcopy_node *node, u32 lo, u16 len)
>> +{
>> + u32 old_lo, old_hi;
>> + u64 sum_len;
>> +
>> + old_lo = node->info.lo;
>> + old_hi = node->info.hi;
>> + sum_len = old_hi - old_lo + 1ULL + len;
>> +
>> + if (sum_len >= (1ULL << 32))
>> + return false;
>> +
>> + if (lo != old_hi + 1)
>> + return false;
>> +
>> + node->info.hi += len;
>> + return true;
>> +}
>> +
>> +static void __msg_zerocopy_uarg_callback(struct ubuf_info_msgzc *uarg)
>> +{
>> + struct sk_buff *skb = skb_from_uarg(uarg);
>> + struct sock *sk = skb->sk;
>> + struct tx_msg_zcopy_node *zcopy_node_p, *tail;
>> + struct tx_msg_zcopy_queue *zcopy_queue;
>> + unsigned long flags;
>> + u32 lo, hi;
>> + u16 len;
>> +
>> + mm_unaccount_pinned_pages(&uarg->mmp);
>> +
>> + /* if !len, there was only 1 call, and it was aborted
>> + * so do not queue a completion notification
>> + */
>> + if (!uarg->len || sock_flag(sk, SOCK_DEAD))
>> + goto release;
>> +
>> + /* only support TCP and UCP currently */
>> + if (sk_is_tcp(sk)) {
>> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
>> + } else if (sk_is_udp(sk)) {
>> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
>> + } else {
>> + pr_warn("MSG_ZEROCOPY_UARG only support TCP && UDP sockets");
>> + goto release;
>> + }
>> +
>> + len = uarg->len;
>> + lo = uarg->id;
>> + hi = uarg->id + len - 1;
>> +
>> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb->data;
>> + zcopy_node_p->info.lo = lo;
>> + zcopy_node_p->info.hi = hi;
>> + zcopy_node_p->info.zerocopy = uarg->zerocopy;
>> +
>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>> + tail = list_last_entry(&zcopy_queue->head, struct tx_msg_zcopy_node, node);
>> + if (!tail || !skb_zerocopy_uarg_notify_extend(tail, lo, len)) {
>> + list_add_tail(&zcopy_node_p->node, &zcopy_queue->head);
>> + skb = NULL;
>> + }
>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>> +release:
>> + consume_skb(skb);
>> + sock_put(sk);
>> +}
>> +
>> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>> + bool success)
>> +{
>> + struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
>> +
>> + uarg_zc->zerocopy = uarg_zc->zerocopy & success;
>> +
>> + if (refcount_dec_and_test(&uarg->refcnt))
>> + __msg_zerocopy_uarg_callback(uarg_zc);
>> +}
>> +EXPORT_SYMBOL_GPL(msg_zerocopy_uarg_callback);
>> +
>> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>> {
>> struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
>> @@ -1838,7 +1957,7 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>> uarg_to_msgzc(uarg)->len--;
>>
>> if (have_uref)
>> - msg_zerocopy_callback(NULL, uarg, true);
>> + uarg->callback(NULL, uarg, true);
>> }
>> EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
>>
>> diff --git a/net/core/sock.c b/net/core/sock.c
>> index 5ed411231fc7..a00ebd71f6ed 100644
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -2843,6 +2843,56 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
>> case SCM_RIGHTS:
>> case SCM_CREDENTIALS:
>> break;
>> + case SO_ZEROCOPY_NOTIFICATION:
>> + if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> + int i = 0;
>> + struct tx_usr_zcopy_info sys_zcopy_info;
>> + struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
>> + struct tx_msg_zcopy_queue *zcopy_queue;
>> + struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
>> + unsigned long flags;
>> +
>> + if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
>> + return -EINVAL;
>> +
>> + if (sk_is_tcp(sk))
>> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
>> + else if (sk_is_udp(sk))
>> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
>> + else
>> + return -EINVAL;
>> +
>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>> + list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
>> + sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
>> + sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
>> + sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
>> + list_del(&zcopy_node_p->node);
>> + zcopy_node_ps[i++] = zcopy_node_p;
>> + if (i == SOCK_USR_ZC_INFO_MAX)
>> + break;
>> + }
>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>> +
>> + if (i > 0) {
>> + sys_zcopy_info.length = i;
>> + if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
>
> This is going to break if user space is 32bit, and kernel 64bit ?
>
Nice catch, thanks for pointing this out!
I may update the code like this?
```
if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)) &&
cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
return -EINVAL;
...
void __user *user;
if (cmsg->cmsg_len == 8)
user = *(void **)CMSG_DATA(cmsg);
else if (cmsg->cmsg_len == 4) {
u32 val = *(u32 *)CMSG_DATA(cmsg);
user = (void *)(uintptr_t)val;
}
copy_to_user(user, ...)
```
I assume it's user's duty to pass in the right address and cmsg_len.
Malicious address or invalid address because of wrong cmsg_len will be
protected by copy_to_user.
> Also SOCK_USR_ZC_INFO_MAX is put in stone, it won't change in the future.
>
In the scenario where users keep calling sendmsg, at most time, the user
will get one notification from the previous sendmsg. Sometimes, users
get two notifications. Thus, we give SOCK_USR_ZC_INFO_MAX a small but
sufficient number 8. We put it in stone here to avoid dynamic allocation
and memory management of the array.
If the memory management worth it, we can change it to a sysctl
variable?
Or, how about we keep SOCK_USR_ZC_INFO_MAX, the max value here, and let
the users pass in the length (could be any number less than MAX) of info
they want to get?
>> + &sys_zcopy_info,
>> + sizeof(sys_zcopy_info))
>
> Your are leaking to user space part of kernel stack, if (i <
> SOCK_USR_ZC_INFO_MAX)
>
Agree, I should do memset to clear the array.
>> + )) {
>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>> + while (i > 0)
>> + list_add(&zcopy_node_ps[--i]->node,
>> + &zcopy_queue->head);
>
>
>
>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>> + return -EFAULT;
>> + }
>> +
>> + while (i > 0)
>> + consume_skb(zcopy_node_ps[--i]->skb);
>> + }
>> + }
>> + break;
>> default:
>> return -EINVAL;
>> }
>> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
>> index 1fe794967211..5adb737c4c01 100644
>> --- a/net/ipv4/ip_output.c
>> +++ b/net/ipv4/ip_output.c
>> @@ -1005,7 +1005,7 @@ static int __ip_append_data(struct sock *sk,
>> (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
>> csummode = CHECKSUM_PARTIAL;
>>
>> - if ((flags & MSG_ZEROCOPY) && length) {
>> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
>> struct msghdr *msg = from;
>>
>> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
>> @@ -1022,7 +1022,9 @@ static int __ip_append_data(struct sock *sk,
>> uarg = msg->msg_ubuf;
>> }
>> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
>> + bool user_args = flags & MSG_ZEROCOPY_UARG;
>> +
>> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb), user_args);
>> if (!uarg)
>> return -ENOBUFS;
>> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>> index e767721b3a58..6254d0eef3af 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -462,6 +462,8 @@ void tcp_init_sock(struct sock *sk)
>>
>> set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
>> sk_sockets_allocated_inc(sk);
>> +
>> + tx_message_zcopy_queue_init(&tp->tx_zcopy_queue);
>> }
>> EXPORT_SYMBOL(tcp_init_sock);
>>
>> @@ -1050,14 +1052,15 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
>>
>> flags = msg->msg_flags;
>>
>> - if ((flags & MSG_ZEROCOPY) && size) {
>> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && size) {
>> if (msg->msg_ubuf) {
>> uarg = msg->msg_ubuf;
>> if (sk->sk_route_caps & NETIF_F_SG)
>> zc = MSG_ZEROCOPY;
>> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> + bool zc_uarg = flags & MSG_ZEROCOPY_UARG;
>> skb = tcp_write_queue_tail(sk);
>> - uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
>> + uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb), zc_uarg);
>> if (!uarg) {
>> err = -ENOBUFS;
>> goto out_err;
>> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
>> index 11460d751e73..6c62aacd74d6 100644
>> --- a/net/ipv4/udp.c
>> +++ b/net/ipv4/udp.c
>> @@ -1126,6 +1126,15 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>> if (ipc.opt)
>> free = 1;
>> connected = 0;
>> +
>> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
>> + * it means this call just wants to get zcopy notifications
>> + * instead of sending packets. It is useful when users
>> + * finish sending and want to get trailing notifications.
>> + */
>> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
>> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
>> + return 0;
>> }
>> if (!ipc.opt) {
>> struct ip_options_rcu *inet_opt;
>> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
>> index b9dd3a66e423..891526ddd74c 100644
>> --- a/net/ipv6/ip6_output.c
>> +++ b/net/ipv6/ip6_output.c
>> @@ -1493,7 +1493,7 @@ static int __ip6_append_data(struct sock *sk,
>> rt->dst.dev->features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
>> csummode = CHECKSUM_PARTIAL;
>>
>> - if ((flags & MSG_ZEROCOPY) && length) {
>> + if (((flags & MSG_ZEROCOPY) || (flags & MSG_ZEROCOPY_UARG)) && length) {
>> struct msghdr *msg = from;
>>
>> if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
>> @@ -1510,7 +1510,8 @@ static int __ip6_append_data(struct sock *sk,
>> uarg = msg->msg_ubuf;
>> }
>> } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
>> - uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
>> + uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
>> + flags & MSG_ZEROCOPY_UARG);
>> if (!uarg)
>> return -ENOBUFS;
>> extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
>> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
>> index 2e4dc5e6137b..98f6905c5db9 100644
>> --- a/net/ipv6/udp.c
>> +++ b/net/ipv6/udp.c
>> @@ -1490,6 +1490,15 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>> if (!(opt->opt_nflen|opt->opt_flen))
>> opt = NULL;
>> connected = false;
>> +
>> + /* If len is zero and flag MSG_ZEROCOPY_UARG is set,
>> + * it means this call just wants to get zcopy notifications
>> + * instead of sending packets. It is useful when users
>> + * finish sending and want to get trailing notifications.
>> + */
>> + if ((msg->msg_flags & MSG_ZEROCOPY_UARG) &&
>> + sock_flag(sk, SOCK_ZEROCOPY) && len == 0)
>> + return 0;
>> }
>> if (!opt) {
>> opt = txopt_get(np);
>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>> index 16ff976a86e3..d6e6830f6ffe 100644
>> --- a/net/vmw_vsock/virtio_transport_common.c
>> +++ b/net/vmw_vsock/virtio_transport_common.c
>> @@ -84,7 +84,7 @@ static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
>>
>> uarg = msg_zerocopy_realloc(sk_vsock(vsk),
>> iter->count,
>> - NULL);
>> + NULL, false);
>> if (!uarg)
>> return -1;
>>
>> --
>> 2.20.1
>>
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [External] Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-10 17:01 ` [External] " Zijian Zhang
@ 2024-04-10 18:57 ` Eric Dumazet
2024-04-10 21:34 ` Zijian Zhang
0 siblings, 1 reply; 24+ messages in thread
From: Eric Dumazet @ 2024-04-10 18:57 UTC (permalink / raw)
To: Zijian Zhang
Cc: netdev, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu
On Wed, Apr 10, 2024 at 7:01 PM Zijian Zhang <zijianzhang@bytedance.com> wrote:
>
> On 4/9/24 2:18 PM, Eric Dumazet wrote:
> > On Tue, Apr 9, 2024 at 10:53 PM <zijianzhang@bytedance.com> wrote:
> >>
> >> From: Zijian Zhang <zijianzhang@bytedance.com>
> >>
> >> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
> >> However, zerocopy is not a free lunch. Apart from the management of user
> >> pages, the combination of poll + recvmsg to receive notifications incurs
> >> unignorable overhead in the applications. The overhead of such sometimes
> >> might be more than the CPU savings from zerocopy. We try to solve this
> >> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
> >> This new mechanism aims to reduce the overhead associated with receiving
> >> notifications by embedding them directly into user arguments passed with
> >> each sendmsg control message. By doing so, we can significantly reduce
> >> the complexity and overhead for managing notifications. In an ideal
> >> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
> >> flag, and the notification will be delivered as soon as possible.
> >>
> >> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
> >> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
> >> ---
> >> include/linux/skbuff.h | 7 +-
> >> include/linux/socket.h | 1 +
> >> include/linux/tcp.h | 3 +
> >> include/linux/udp.h | 3 +
> >> include/net/sock.h | 17 +++
> >> include/net/udp.h | 1 +
> >> include/uapi/asm-generic/socket.h | 2 +
> >> include/uapi/linux/socket.h | 17 +++
> >> net/core/skbuff.c | 137 ++++++++++++++++++++++--
> >> net/core/sock.c | 50 +++++++++
> >> net/ipv4/ip_output.c | 6 +-
> >> net/ipv4/tcp.c | 7 +-
> >> net/ipv4/udp.c | 9 ++
> >> net/ipv6/ip6_output.c | 5 +-
> >> net/ipv6/udp.c | 9 ++
> >> net/vmw_vsock/virtio_transport_common.c | 2 +-
> >> 16 files changed, 258 insertions(+), 18 deletions(-)
> >>
> >> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> >> index 03ea36a82cdd..19b94ba01007 100644
> >> --- a/include/linux/skbuff.h
> >> +++ b/include/linux/skbuff.h
> >> @@ -1663,12 +1663,14 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
> >> #endif
> >>
> >> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> >> - struct ubuf_info *uarg);
> >> + struct ubuf_info *uarg, bool user_args_notification);
> >>
> >> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
> >>
> >> void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> >> bool success);
> >> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> >> + bool success);
> >>
> >> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
> >> struct sk_buff *skb, struct iov_iter *from,
> >> @@ -1763,7 +1765,8 @@ static inline void net_zcopy_put(struct ubuf_info *uarg)
> >> static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> >> {
> >> if (uarg) {
> >> - if (uarg->callback == msg_zerocopy_callback)
> >> + if (uarg->callback == msg_zerocopy_callback ||
> >> + uarg->callback == msg_zerocopy_uarg_callback)
> >> msg_zerocopy_put_abort(uarg, have_uref);
> >> else if (have_uref)
> >> net_zcopy_put(uarg);
> >> diff --git a/include/linux/socket.h b/include/linux/socket.h
> >> index 139c330ccf2c..de01392344e1 100644
> >> --- a/include/linux/socket.h
> >> +++ b/include/linux/socket.h
> >> @@ -326,6 +326,7 @@ struct ucred {
> >> * plain text and require encryption
> >> */
> >>
> >> +#define MSG_ZEROCOPY_UARG 0x2000000 /* MSG_ZEROCOPY with UARG notifications */
> >> #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
> >> #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
> >> #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
> >> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
> >> index 55399ee2a57e..e973f4990646 100644
> >> --- a/include/linux/tcp.h
> >> +++ b/include/linux/tcp.h
> >> @@ -501,6 +501,9 @@ struct tcp_sock {
> >> */
> >> struct request_sock __rcu *fastopen_rsk;
> >> struct saved_syn *saved_syn;
> >> +
> >> +/* TCP MSG_ZEROCOPY_UARG related information */
> >> + struct tx_msg_zcopy_queue tx_zcopy_queue;
> >> };
> >>
> >> enum tsq_enum {
> >> diff --git a/include/linux/udp.h b/include/linux/udp.h
> >> index 3748e82b627b..502b393eac67 100644
> >> --- a/include/linux/udp.h
> >> +++ b/include/linux/udp.h
> >> @@ -95,6 +95,9 @@ struct udp_sock {
> >>
> >> /* Cache friendly copy of sk->sk_peek_off >= 0 */
> >> bool peeking_with_offset;
> >> +
> >> + /* This field is used by sendmsg zcopy user arg mode notification */
> >> + struct tx_msg_zcopy_queue tx_zcopy_queue;
> >> };
> >>
> >> #define udp_test_bit(nr, sk) \
> >> diff --git a/include/net/sock.h b/include/net/sock.h
> >> index 2253eefe2848..f7c045e98213 100644
> >> --- a/include/net/sock.h
> >> +++ b/include/net/sock.h
> >> @@ -544,6 +544,23 @@ struct sock {
> >> netns_tracker ns_tracker;
> >> };
> >>
> >> +struct tx_msg_zcopy_node {
> >> + struct list_head node;
> >> + struct tx_msg_zcopy_info info;
> >> + struct sk_buff *skb;
> >> +};
> >> +
> >> +struct tx_msg_zcopy_queue {
> >> + struct list_head head;
> >> + spinlock_t lock; /* protects head queue */
> >> +};
> >> +
> >> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
> >> +{
> >> + spin_lock_init(&q->lock);
> >> + INIT_LIST_HEAD(&q->head);
> >> +}
> >> +
> >> enum sk_pacing {
> >> SK_PACING_NONE = 0,
> >> SK_PACING_NEEDED = 1,
> >> diff --git a/include/net/udp.h b/include/net/udp.h
> >> index 488a6d2babcc..9e4d7b128de4 100644
> >> --- a/include/net/udp.h
> >> +++ b/include/net/udp.h
> >> @@ -182,6 +182,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
> >> skb_queue_head_init(&up->reader_queue);
> >> up->forward_threshold = sk->sk_rcvbuf >> 2;
> >> set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
> >> + tx_message_zcopy_queue_init(&up->tx_zcopy_queue);
> >> }
> >>
> >> /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
> >> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
> >> index 8ce8a39a1e5f..86aa4b5cb7f1 100644
> >> --- a/include/uapi/asm-generic/socket.h
> >> +++ b/include/uapi/asm-generic/socket.h
> >> @@ -135,6 +135,8 @@
> >> #define SO_PASSPIDFD 76
> >> #define SO_PEERPIDFD 77
> >>
> >> +#define SO_ZEROCOPY_NOTIFICATION 78
> >> +
> >> #if !defined(__KERNEL__)
> >>
> >> #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
> >> diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
> >> index d3fcd3b5ec53..469ed8f4e6c8 100644
> >> --- a/include/uapi/linux/socket.h
> >> +++ b/include/uapi/linux/socket.h
> >> @@ -35,4 +35,21 @@ struct __kernel_sockaddr_storage {
> >> #define SOCK_TXREHASH_DISABLED 0
> >> #define SOCK_TXREHASH_ENABLED 1
> >>
> >> +/*
> >> + * Given the fact that MSG_ZEROCOPY_UARG tries to copy notifications
> >> + * back to user as soon as possible, 8 should be sufficient.
> >> + */
> >> +#define SOCK_USR_ZC_INFO_MAX 8
> >> +
> >> +struct tx_msg_zcopy_info {
> >> + __u32 lo;
> >> + __u32 hi;
> >> + __u8 zerocopy;
> >> +};
> >> +
> >> +struct tx_usr_zcopy_info {
> >> + int length;
> >> + struct tx_msg_zcopy_info info[SOCK_USR_ZC_INFO_MAX];
> >> +};
> >> +
> >> #endif /* _UAPI_LINUX_SOCKET_H */
> >> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> >> index 2a5ce6667bbb..d939b2c14d55 100644
> >> --- a/net/core/skbuff.c
> >> +++ b/net/core/skbuff.c
> >> @@ -1661,6 +1661,16 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
> >> }
> >> EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
> >>
> >> +static void init_ubuf_info_msgzc(struct ubuf_info_msgzc *uarg, struct sock *sk, size_t size)
> >> +{
> >> + uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
> >> + uarg->len = 1;
> >> + uarg->bytelen = size;
> >> + uarg->zerocopy = 1;
> >> + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> >> + refcount_set(&uarg->ubuf.refcnt, 1);
> >> +}
> >> +
> >> static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
> >> {
> >> struct ubuf_info_msgzc *uarg;
> >> @@ -1682,12 +1692,38 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
> >> }
> >>
> >> uarg->ubuf.callback = msg_zerocopy_callback;
> >> - uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
> >> - uarg->len = 1;
> >> - uarg->bytelen = size;
> >> - uarg->zerocopy = 1;
> >> - uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
> >> - refcount_set(&uarg->ubuf.refcnt, 1);
> >> + init_ubuf_info_msgzc(uarg, sk, size);
> >> + sock_hold(sk);
> >> +
> >> + return &uarg->ubuf;
> >> +}
> >> +
> >> +static struct ubuf_info *msg_zerocopy_uarg_alloc(struct sock *sk, size_t size)
> >> +{
> >> + struct sk_buff *skb;
> >> + struct ubuf_info_msgzc *uarg;
> >> + struct tx_msg_zcopy_node *zcopy_node_p;
> >> +
> >> + WARN_ON_ONCE(!in_task());
> >> +
> >> + skb = sock_omalloc(sk, sizeof(*zcopy_node_p), GFP_KERNEL);
> >> + if (!skb)
> >> + return NULL;
> >> +
> >> + BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
> >> + uarg = (void *)skb->cb;
> >> + uarg->mmp.user = NULL;
> >> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb_put(skb, sizeof(*zcopy_node_p));
> >> +
> >> + if (mm_account_pinned_pages(&uarg->mmp, size)) {
> >> + kfree_skb(skb);
> >> + return NULL;
> >> + }
> >> +
> >> + INIT_LIST_HEAD(&zcopy_node_p->node);
> >> + zcopy_node_p->skb = skb;
> >> + uarg->ubuf.callback = msg_zerocopy_uarg_callback;
> >> + init_ubuf_info_msgzc(uarg, sk, size);
> >> sock_hold(sk);
> >>
> >> return &uarg->ubuf;
> >> @@ -1699,7 +1735,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
> >> }
> >>
> >> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> >> - struct ubuf_info *uarg)
> >> + struct ubuf_info *uarg, bool usr_arg_notification)
> >> {
> >> if (uarg) {
> >> struct ubuf_info_msgzc *uarg_zc;
> >> @@ -1707,7 +1743,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> >> u32 bytelen, next;
> >>
> >> /* there might be non MSG_ZEROCOPY users */
> >> - if (uarg->callback != msg_zerocopy_callback)
> >> + if (uarg->callback != msg_zerocopy_callback &&
> >> + uarg->callback != msg_zerocopy_uarg_callback)
> >> return NULL;
> >>
> >> /* realloc only when socket is locked (TCP, UDP cork),
> >> @@ -1744,6 +1781,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
> >> }
> >>
> >> new_alloc:
> >> + if (usr_arg_notification)
> >> + return msg_zerocopy_uarg_alloc(sk, size);
> >> return msg_zerocopy_alloc(sk, size);
> >> }
> >> EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
> >> @@ -1830,6 +1869,86 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> >> }
> >> EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
> >>
> >> +static bool skb_zerocopy_uarg_notify_extend(struct tx_msg_zcopy_node *node, u32 lo, u16 len)
> >> +{
> >> + u32 old_lo, old_hi;
> >> + u64 sum_len;
> >> +
> >> + old_lo = node->info.lo;
> >> + old_hi = node->info.hi;
> >> + sum_len = old_hi - old_lo + 1ULL + len;
> >> +
> >> + if (sum_len >= (1ULL << 32))
> >> + return false;
> >> +
> >> + if (lo != old_hi + 1)
> >> + return false;
> >> +
> >> + node->info.hi += len;
> >> + return true;
> >> +}
> >> +
> >> +static void __msg_zerocopy_uarg_callback(struct ubuf_info_msgzc *uarg)
> >> +{
> >> + struct sk_buff *skb = skb_from_uarg(uarg);
> >> + struct sock *sk = skb->sk;
> >> + struct tx_msg_zcopy_node *zcopy_node_p, *tail;
> >> + struct tx_msg_zcopy_queue *zcopy_queue;
> >> + unsigned long flags;
> >> + u32 lo, hi;
> >> + u16 len;
> >> +
> >> + mm_unaccount_pinned_pages(&uarg->mmp);
> >> +
> >> + /* if !len, there was only 1 call, and it was aborted
> >> + * so do not queue a completion notification
> >> + */
> >> + if (!uarg->len || sock_flag(sk, SOCK_DEAD))
> >> + goto release;
> >> +
> >> + /* only support TCP and UCP currently */
> >> + if (sk_is_tcp(sk)) {
> >> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
> >> + } else if (sk_is_udp(sk)) {
> >> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
> >> + } else {
> >> + pr_warn("MSG_ZEROCOPY_UARG only support TCP && UDP sockets");
> >> + goto release;
> >> + }
> >> +
> >> + len = uarg->len;
> >> + lo = uarg->id;
> >> + hi = uarg->id + len - 1;
> >> +
> >> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb->data;
> >> + zcopy_node_p->info.lo = lo;
> >> + zcopy_node_p->info.hi = hi;
> >> + zcopy_node_p->info.zerocopy = uarg->zerocopy;
> >> +
> >> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> >> + tail = list_last_entry(&zcopy_queue->head, struct tx_msg_zcopy_node, node);
> >> + if (!tail || !skb_zerocopy_uarg_notify_extend(tail, lo, len)) {
> >> + list_add_tail(&zcopy_node_p->node, &zcopy_queue->head);
> >> + skb = NULL;
> >> + }
> >> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> >> +release:
> >> + consume_skb(skb);
> >> + sock_put(sk);
> >> +}
> >> +
> >> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
> >> + bool success)
> >> +{
> >> + struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
> >> +
> >> + uarg_zc->zerocopy = uarg_zc->zerocopy & success;
> >> +
> >> + if (refcount_dec_and_test(&uarg->refcnt))
> >> + __msg_zerocopy_uarg_callback(uarg_zc);
> >> +}
> >> +EXPORT_SYMBOL_GPL(msg_zerocopy_uarg_callback);
> >> +
> >> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> >> {
> >> struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
> >> @@ -1838,7 +1957,7 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
> >> uarg_to_msgzc(uarg)->len--;
> >>
> >> if (have_uref)
> >> - msg_zerocopy_callback(NULL, uarg, true);
> >> + uarg->callback(NULL, uarg, true);
> >> }
> >> EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
> >>
> >> diff --git a/net/core/sock.c b/net/core/sock.c
> >> index 5ed411231fc7..a00ebd71f6ed 100644
> >> --- a/net/core/sock.c
> >> +++ b/net/core/sock.c
> >> @@ -2843,6 +2843,56 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
> >> case SCM_RIGHTS:
> >> case SCM_CREDENTIALS:
> >> break;
> >> + case SO_ZEROCOPY_NOTIFICATION:
> >> + if (sock_flag(sk, SOCK_ZEROCOPY)) {
> >> + int i = 0;
> >> + struct tx_usr_zcopy_info sys_zcopy_info;
> >> + struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
> >> + struct tx_msg_zcopy_queue *zcopy_queue;
> >> + struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
> >> + unsigned long flags;
> >> +
> >> + if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
> >> + return -EINVAL;
> >> +
> >> + if (sk_is_tcp(sk))
> >> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
> >> + else if (sk_is_udp(sk))
> >> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
> >> + else
> >> + return -EINVAL;
> >> +
> >> + spin_lock_irqsave(&zcopy_queue->lock, flags);
> >> + list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
> >> + sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
> >> + sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
> >> + sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
> >> + list_del(&zcopy_node_p->node);
> >> + zcopy_node_ps[i++] = zcopy_node_p;
> >> + if (i == SOCK_USR_ZC_INFO_MAX)
> >> + break;
> >> + }
> >> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
> >> +
> >> + if (i > 0) {
> >> + sys_zcopy_info.length = i;
> >> + if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
> >
> > This is going to break if user space is 32bit, and kernel 64bit ?
> >
>
> Nice catch, thanks for pointing this out!
>
> I may update the code like this?
>
> ```
> if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)) &&
> cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
> return -EINVAL;
>
> ...
I would instead use u64 convention, instead of "void *" or u32.
>
> void __user *user;
> if (cmsg->cmsg_len == 8)
> user = *(void **)CMSG_DATA(cmsg);
> else if (cmsg->cmsg_len == 4) {
> u32 val = *(u32 *)CMSG_DATA(cmsg);
> user = (void *)(uintptr_t)val;
> }
> copy_to_user(user, ...)
> ```
>
> I assume it's user's duty to pass in the right address and cmsg_len.
> Malicious address or invalid address because of wrong cmsg_len will be
> protected by copy_to_user.
>
> > Also SOCK_USR_ZC_INFO_MAX is put in stone, it won't change in the future.
> >
>
> In the scenario where users keep calling sendmsg, at most time, the user
> will get one notification from the previous sendmsg. Sometimes, users
> get two notifications. Thus, we give SOCK_USR_ZC_INFO_MAX a small but
> sufficient number 8. We put it in stone here to avoid dynamic allocation
> and memory management of the array.
>
> If the memory management worth it, we can change it to a sysctl
> variable?
Convention for user space -> kernel space , is to pass not only a base
pointer, but also a length.
Of course the kernel implementation can still use a local/automatic
array in the stack with 8 elems,
but this could change eventually
Few system calls that did not follow this convention had to be
extended to other system calls.
>
> Or, how about we keep SOCK_USR_ZC_INFO_MAX, the max value here, and let
> the users pass in the length (could be any number less than MAX) of info
> they want to get?
>
> >> + &sys_zcopy_info,
> >> + sizeof(sys_zcopy_info))
> >
> > Your are leaking to user space part of kernel stack, if (i <
> > SOCK_USR_ZC_INFO_MAX)
> >
>
> Agree, I should do memset to clear the array.
Or copy only the part that has been initialized, struct_size() might help ...
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [External] Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-10 18:57 ` Eric Dumazet
@ 2024-04-10 21:34 ` Zijian Zhang
0 siblings, 0 replies; 24+ messages in thread
From: Zijian Zhang @ 2024-04-10 21:34 UTC (permalink / raw)
To: Eric Dumazet
Cc: netdev, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu
On 4/10/24 11:57 AM, Eric Dumazet wrote:
> On Wed, Apr 10, 2024 at 7:01 PM Zijian Zhang <zijianzhang@bytedance.com> wrote:
>>
>> On 4/9/24 2:18 PM, Eric Dumazet wrote:
>>> On Tue, Apr 9, 2024 at 10:53 PM <zijianzhang@bytedance.com> wrote:
>>>>
>>>> From: Zijian Zhang <zijianzhang@bytedance.com>
>>>>
>>>> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
>>>> However, zerocopy is not a free lunch. Apart from the management of user
>>>> pages, the combination of poll + recvmsg to receive notifications incurs
>>>> unignorable overhead in the applications. The overhead of such sometimes
>>>> might be more than the CPU savings from zerocopy. We try to solve this
>>>> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
>>>> This new mechanism aims to reduce the overhead associated with receiving
>>>> notifications by embedding them directly into user arguments passed with
>>>> each sendmsg control message. By doing so, we can significantly reduce
>>>> the complexity and overhead for managing notifications. In an ideal
>>>> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
>>>> flag, and the notification will be delivered as soon as possible.
>>>>
>>>> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
>>>> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
>>>> ---
>>>> include/linux/skbuff.h | 7 +-
>>>> include/linux/socket.h | 1 +
>>>> include/linux/tcp.h | 3 +
>>>> include/linux/udp.h | 3 +
>>>> include/net/sock.h | 17 +++
>>>> include/net/udp.h | 1 +
>>>> include/uapi/asm-generic/socket.h | 2 +
>>>> include/uapi/linux/socket.h | 17 +++
>>>> net/core/skbuff.c | 137 ++++++++++++++++++++++--
>>>> net/core/sock.c | 50 +++++++++
>>>> net/ipv4/ip_output.c | 6 +-
>>>> net/ipv4/tcp.c | 7 +-
>>>> net/ipv4/udp.c | 9 ++
>>>> net/ipv6/ip6_output.c | 5 +-
>>>> net/ipv6/udp.c | 9 ++
>>>> net/vmw_vsock/virtio_transport_common.c | 2 +-
>>>> 16 files changed, 258 insertions(+), 18 deletions(-)
>>>>
>>>> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
>>>> index 03ea36a82cdd..19b94ba01007 100644
>>>> --- a/include/linux/skbuff.h
>>>> +++ b/include/linux/skbuff.h
>>>> @@ -1663,12 +1663,14 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
>>>> #endif
>>>>
>>>> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>>>> - struct ubuf_info *uarg);
>>>> + struct ubuf_info *uarg, bool user_args_notification);
>>>>
>>>> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
>>>>
>>>> void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>>>> bool success);
>>>> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>>>> + bool success);
>>>>
>>>> int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
>>>> struct sk_buff *skb, struct iov_iter *from,
>>>> @@ -1763,7 +1765,8 @@ static inline void net_zcopy_put(struct ubuf_info *uarg)
>>>> static inline void net_zcopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>>>> {
>>>> if (uarg) {
>>>> - if (uarg->callback == msg_zerocopy_callback)
>>>> + if (uarg->callback == msg_zerocopy_callback ||
>>>> + uarg->callback == msg_zerocopy_uarg_callback)
>>>> msg_zerocopy_put_abort(uarg, have_uref);
>>>> else if (have_uref)
>>>> net_zcopy_put(uarg);
>>>> diff --git a/include/linux/socket.h b/include/linux/socket.h
>>>> index 139c330ccf2c..de01392344e1 100644
>>>> --- a/include/linux/socket.h
>>>> +++ b/include/linux/socket.h
>>>> @@ -326,6 +326,7 @@ struct ucred {
>>>> * plain text and require encryption
>>>> */
>>>>
>>>> +#define MSG_ZEROCOPY_UARG 0x2000000 /* MSG_ZEROCOPY with UARG notifications */
>>>> #define MSG_ZEROCOPY 0x4000000 /* Use user data in kernel path */
>>>> #define MSG_SPLICE_PAGES 0x8000000 /* Splice the pages from the iterator in sendmsg() */
>>>> #define MSG_FASTOPEN 0x20000000 /* Send data in TCP SYN */
>>>> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
>>>> index 55399ee2a57e..e973f4990646 100644
>>>> --- a/include/linux/tcp.h
>>>> +++ b/include/linux/tcp.h
>>>> @@ -501,6 +501,9 @@ struct tcp_sock {
>>>> */
>>>> struct request_sock __rcu *fastopen_rsk;
>>>> struct saved_syn *saved_syn;
>>>> +
>>>> +/* TCP MSG_ZEROCOPY_UARG related information */
>>>> + struct tx_msg_zcopy_queue tx_zcopy_queue;
>>>> };
>>>>
>>>> enum tsq_enum {
>>>> diff --git a/include/linux/udp.h b/include/linux/udp.h
>>>> index 3748e82b627b..502b393eac67 100644
>>>> --- a/include/linux/udp.h
>>>> +++ b/include/linux/udp.h
>>>> @@ -95,6 +95,9 @@ struct udp_sock {
>>>>
>>>> /* Cache friendly copy of sk->sk_peek_off >= 0 */
>>>> bool peeking_with_offset;
>>>> +
>>>> + /* This field is used by sendmsg zcopy user arg mode notification */
>>>> + struct tx_msg_zcopy_queue tx_zcopy_queue;
>>>> };
>>>>
>>>> #define udp_test_bit(nr, sk) \
>>>> diff --git a/include/net/sock.h b/include/net/sock.h
>>>> index 2253eefe2848..f7c045e98213 100644
>>>> --- a/include/net/sock.h
>>>> +++ b/include/net/sock.h
>>>> @@ -544,6 +544,23 @@ struct sock {
>>>> netns_tracker ns_tracker;
>>>> };
>>>>
>>>> +struct tx_msg_zcopy_node {
>>>> + struct list_head node;
>>>> + struct tx_msg_zcopy_info info;
>>>> + struct sk_buff *skb;
>>>> +};
>>>> +
>>>> +struct tx_msg_zcopy_queue {
>>>> + struct list_head head;
>>>> + spinlock_t lock; /* protects head queue */
>>>> +};
>>>> +
>>>> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
>>>> +{
>>>> + spin_lock_init(&q->lock);
>>>> + INIT_LIST_HEAD(&q->head);
>>>> +}
>>>> +
>>>> enum sk_pacing {
>>>> SK_PACING_NONE = 0,
>>>> SK_PACING_NEEDED = 1,
>>>> diff --git a/include/net/udp.h b/include/net/udp.h
>>>> index 488a6d2babcc..9e4d7b128de4 100644
>>>> --- a/include/net/udp.h
>>>> +++ b/include/net/udp.h
>>>> @@ -182,6 +182,7 @@ static inline void udp_lib_init_sock(struct sock *sk)
>>>> skb_queue_head_init(&up->reader_queue);
>>>> up->forward_threshold = sk->sk_rcvbuf >> 2;
>>>> set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
>>>> + tx_message_zcopy_queue_init(&up->tx_zcopy_queue);
>>>> }
>>>>
>>>> /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
>>>> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
>>>> index 8ce8a39a1e5f..86aa4b5cb7f1 100644
>>>> --- a/include/uapi/asm-generic/socket.h
>>>> +++ b/include/uapi/asm-generic/socket.h
>>>> @@ -135,6 +135,8 @@
>>>> #define SO_PASSPIDFD 76
>>>> #define SO_PEERPIDFD 77
>>>>
>>>> +#define SO_ZEROCOPY_NOTIFICATION 78
>>>> +
>>>> #if !defined(__KERNEL__)
>>>>
>>>> #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
>>>> diff --git a/include/uapi/linux/socket.h b/include/uapi/linux/socket.h
>>>> index d3fcd3b5ec53..469ed8f4e6c8 100644
>>>> --- a/include/uapi/linux/socket.h
>>>> +++ b/include/uapi/linux/socket.h
>>>> @@ -35,4 +35,21 @@ struct __kernel_sockaddr_storage {
>>>> #define SOCK_TXREHASH_DISABLED 0
>>>> #define SOCK_TXREHASH_ENABLED 1
>>>>
>>>> +/*
>>>> + * Given the fact that MSG_ZEROCOPY_UARG tries to copy notifications
>>>> + * back to user as soon as possible, 8 should be sufficient.
>>>> + */
>>>> +#define SOCK_USR_ZC_INFO_MAX 8
>>>> +
>>>> +struct tx_msg_zcopy_info {
>>>> + __u32 lo;
>>>> + __u32 hi;
>>>> + __u8 zerocopy;
>>>> +};
>>>> +
>>>> +struct tx_usr_zcopy_info {
>>>> + int length;
>>>> + struct tx_msg_zcopy_info info[SOCK_USR_ZC_INFO_MAX];
>>>> +};
>>>> +
>>>> #endif /* _UAPI_LINUX_SOCKET_H */
>>>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
>>>> index 2a5ce6667bbb..d939b2c14d55 100644
>>>> --- a/net/core/skbuff.c
>>>> +++ b/net/core/skbuff.c
>>>> @@ -1661,6 +1661,16 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
>>>> }
>>>> EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
>>>>
>>>> +static void init_ubuf_info_msgzc(struct ubuf_info_msgzc *uarg, struct sock *sk, size_t size)
>>>> +{
>>>> + uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
>>>> + uarg->len = 1;
>>>> + uarg->bytelen = size;
>>>> + uarg->zerocopy = 1;
>>>> + uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
>>>> + refcount_set(&uarg->ubuf.refcnt, 1);
>>>> +}
>>>> +
>>>> static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
>>>> {
>>>> struct ubuf_info_msgzc *uarg;
>>>> @@ -1682,12 +1692,38 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
>>>> }
>>>>
>>>> uarg->ubuf.callback = msg_zerocopy_callback;
>>>> - uarg->id = ((u32)atomic_inc_return(&sk->sk_zckey)) - 1;
>>>> - uarg->len = 1;
>>>> - uarg->bytelen = size;
>>>> - uarg->zerocopy = 1;
>>>> - uarg->ubuf.flags = SKBFL_ZEROCOPY_FRAG | SKBFL_DONT_ORPHAN;
>>>> - refcount_set(&uarg->ubuf.refcnt, 1);
>>>> + init_ubuf_info_msgzc(uarg, sk, size);
>>>> + sock_hold(sk);
>>>> +
>>>> + return &uarg->ubuf;
>>>> +}
>>>> +
>>>> +static struct ubuf_info *msg_zerocopy_uarg_alloc(struct sock *sk, size_t size)
>>>> +{
>>>> + struct sk_buff *skb;
>>>> + struct ubuf_info_msgzc *uarg;
>>>> + struct tx_msg_zcopy_node *zcopy_node_p;
>>>> +
>>>> + WARN_ON_ONCE(!in_task());
>>>> +
>>>> + skb = sock_omalloc(sk, sizeof(*zcopy_node_p), GFP_KERNEL);
>>>> + if (!skb)
>>>> + return NULL;
>>>> +
>>>> + BUILD_BUG_ON(sizeof(*uarg) > sizeof(skb->cb));
>>>> + uarg = (void *)skb->cb;
>>>> + uarg->mmp.user = NULL;
>>>> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb_put(skb, sizeof(*zcopy_node_p));
>>>> +
>>>> + if (mm_account_pinned_pages(&uarg->mmp, size)) {
>>>> + kfree_skb(skb);
>>>> + return NULL;
>>>> + }
>>>> +
>>>> + INIT_LIST_HEAD(&zcopy_node_p->node);
>>>> + zcopy_node_p->skb = skb;
>>>> + uarg->ubuf.callback = msg_zerocopy_uarg_callback;
>>>> + init_ubuf_info_msgzc(uarg, sk, size);
>>>> sock_hold(sk);
>>>>
>>>> return &uarg->ubuf;
>>>> @@ -1699,7 +1735,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
>>>> }
>>>>
>>>> struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>>>> - struct ubuf_info *uarg)
>>>> + struct ubuf_info *uarg, bool usr_arg_notification)
>>>> {
>>>> if (uarg) {
>>>> struct ubuf_info_msgzc *uarg_zc;
>>>> @@ -1707,7 +1743,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>>>> u32 bytelen, next;
>>>>
>>>> /* there might be non MSG_ZEROCOPY users */
>>>> - if (uarg->callback != msg_zerocopy_callback)
>>>> + if (uarg->callback != msg_zerocopy_callback &&
>>>> + uarg->callback != msg_zerocopy_uarg_callback)
>>>> return NULL;
>>>>
>>>> /* realloc only when socket is locked (TCP, UDP cork),
>>>> @@ -1744,6 +1781,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
>>>> }
>>>>
>>>> new_alloc:
>>>> + if (usr_arg_notification)
>>>> + return msg_zerocopy_uarg_alloc(sk, size);
>>>> return msg_zerocopy_alloc(sk, size);
>>>> }
>>>> EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
>>>> @@ -1830,6 +1869,86 @@ void msg_zerocopy_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>>>> }
>>>> EXPORT_SYMBOL_GPL(msg_zerocopy_callback);
>>>>
>>>> +static bool skb_zerocopy_uarg_notify_extend(struct tx_msg_zcopy_node *node, u32 lo, u16 len)
>>>> +{
>>>> + u32 old_lo, old_hi;
>>>> + u64 sum_len;
>>>> +
>>>> + old_lo = node->info.lo;
>>>> + old_hi = node->info.hi;
>>>> + sum_len = old_hi - old_lo + 1ULL + len;
>>>> +
>>>> + if (sum_len >= (1ULL << 32))
>>>> + return false;
>>>> +
>>>> + if (lo != old_hi + 1)
>>>> + return false;
>>>> +
>>>> + node->info.hi += len;
>>>> + return true;
>>>> +}
>>>> +
>>>> +static void __msg_zerocopy_uarg_callback(struct ubuf_info_msgzc *uarg)
>>>> +{
>>>> + struct sk_buff *skb = skb_from_uarg(uarg);
>>>> + struct sock *sk = skb->sk;
>>>> + struct tx_msg_zcopy_node *zcopy_node_p, *tail;
>>>> + struct tx_msg_zcopy_queue *zcopy_queue;
>>>> + unsigned long flags;
>>>> + u32 lo, hi;
>>>> + u16 len;
>>>> +
>>>> + mm_unaccount_pinned_pages(&uarg->mmp);
>>>> +
>>>> + /* if !len, there was only 1 call, and it was aborted
>>>> + * so do not queue a completion notification
>>>> + */
>>>> + if (!uarg->len || sock_flag(sk, SOCK_DEAD))
>>>> + goto release;
>>>> +
>>>> + /* only support TCP and UCP currently */
>>>> + if (sk_is_tcp(sk)) {
>>>> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
>>>> + } else if (sk_is_udp(sk)) {
>>>> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
>>>> + } else {
>>>> + pr_warn("MSG_ZEROCOPY_UARG only support TCP && UDP sockets");
>>>> + goto release;
>>>> + }
>>>> +
>>>> + len = uarg->len;
>>>> + lo = uarg->id;
>>>> + hi = uarg->id + len - 1;
>>>> +
>>>> + zcopy_node_p = (struct tx_msg_zcopy_node *)skb->data;
>>>> + zcopy_node_p->info.lo = lo;
>>>> + zcopy_node_p->info.hi = hi;
>>>> + zcopy_node_p->info.zerocopy = uarg->zerocopy;
>>>> +
>>>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>>>> + tail = list_last_entry(&zcopy_queue->head, struct tx_msg_zcopy_node, node);
>>>> + if (!tail || !skb_zerocopy_uarg_notify_extend(tail, lo, len)) {
>>>> + list_add_tail(&zcopy_node_p->node, &zcopy_queue->head);
>>>> + skb = NULL;
>>>> + }
>>>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>>>> +release:
>>>> + consume_skb(skb);
>>>> + sock_put(sk);
>>>> +}
>>>> +
>>>> +void msg_zerocopy_uarg_callback(struct sk_buff *skb, struct ubuf_info *uarg,
>>>> + bool success)
>>>> +{
>>>> + struct ubuf_info_msgzc *uarg_zc = uarg_to_msgzc(uarg);
>>>> +
>>>> + uarg_zc->zerocopy = uarg_zc->zerocopy & success;
>>>> +
>>>> + if (refcount_dec_and_test(&uarg->refcnt))
>>>> + __msg_zerocopy_uarg_callback(uarg_zc);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(msg_zerocopy_uarg_callback);
>>>> +
>>>> void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>>>> {
>>>> struct sock *sk = skb_from_uarg(uarg_to_msgzc(uarg))->sk;
>>>> @@ -1838,7 +1957,7 @@ void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref)
>>>> uarg_to_msgzc(uarg)->len--;
>>>>
>>>> if (have_uref)
>>>> - msg_zerocopy_callback(NULL, uarg, true);
>>>> + uarg->callback(NULL, uarg, true);
>>>> }
>>>> EXPORT_SYMBOL_GPL(msg_zerocopy_put_abort);
>>>>
>>>> diff --git a/net/core/sock.c b/net/core/sock.c
>>>> index 5ed411231fc7..a00ebd71f6ed 100644
>>>> --- a/net/core/sock.c
>>>> +++ b/net/core/sock.c
>>>> @@ -2843,6 +2843,56 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
>>>> case SCM_RIGHTS:
>>>> case SCM_CREDENTIALS:
>>>> break;
>>>> + case SO_ZEROCOPY_NOTIFICATION:
>>>> + if (sock_flag(sk, SOCK_ZEROCOPY)) {
>>>> + int i = 0;
>>>> + struct tx_usr_zcopy_info sys_zcopy_info;
>>>> + struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
>>>> + struct tx_msg_zcopy_queue *zcopy_queue;
>>>> + struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
>>>> + unsigned long flags;
>>>> +
>>>> + if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
>>>> + return -EINVAL;
>>>> +
>>>> + if (sk_is_tcp(sk))
>>>> + zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
>>>> + else if (sk_is_udp(sk))
>>>> + zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
>>>> + else
>>>> + return -EINVAL;
>>>> +
>>>> + spin_lock_irqsave(&zcopy_queue->lock, flags);
>>>> + list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
>>>> + sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
>>>> + sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
>>>> + sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
>>>> + list_del(&zcopy_node_p->node);
>>>> + zcopy_node_ps[i++] = zcopy_node_p;
>>>> + if (i == SOCK_USR_ZC_INFO_MAX)
>>>> + break;
>>>> + }
>>>> + spin_unlock_irqrestore(&zcopy_queue->lock, flags);
>>>> +
>>>> + if (i > 0) {
>>>> + sys_zcopy_info.length = i;
>>>> + if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
>>>
>>> This is going to break if user space is 32bit, and kernel 64bit ?
>>>
>>
>> Nice catch, thanks for pointing this out!
>>
>> I may update the code like this?
>>
>> ```
>> if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)) &&
>> cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
>> return -EINVAL;
>>
>> ...
>
> I would instead use u64 convention, instead of "void *" or u32.
>
>>
>> void __user *user;
>> if (cmsg->cmsg_len == 8)
>> user = *(void **)CMSG_DATA(cmsg);
>> else if (cmsg->cmsg_len == 4) {
>> u32 val = *(u32 *)CMSG_DATA(cmsg);
>> user = (void *)(uintptr_t)val;
>> }
>> copy_to_user(user, ...)
>> ```
>>
>> I assume it's user's duty to pass in the right address and cmsg_len.
>> Malicious address or invalid address because of wrong cmsg_len will be
>> protected by copy_to_user.
>
>
>
>>
>>> Also SOCK_USR_ZC_INFO_MAX is put in stone, it won't change in the future.
>>>
>>
>> In the scenario where users keep calling sendmsg, at most time, the user
>> will get one notification from the previous sendmsg. Sometimes, users
>> get two notifications. Thus, we give SOCK_USR_ZC_INFO_MAX a small but
>> sufficient number 8. We put it in stone here to avoid dynamic allocation
>> and memory management of the array.
>>
>> If the memory management worth it, we can change it to a sysctl
>> variable?
>
> Convention for user space -> kernel space , is to pass not only a base
> pointer, but also a length.
>
> Of course the kernel implementation can still use a local/automatic
> array in the stack with 8 elems,
> but this could change eventually
>
> Few system calls that did not follow this convention had to be
> extended to other system calls.
>
>>
>> Or, how about we keep SOCK_USR_ZC_INFO_MAX, the max value here, and let
>> the users pass in the length (could be any number less than MAX) of info
>> they want to get?
>>
>>>> + &sys_zcopy_info,
>>>> + sizeof(sys_zcopy_info))
>>>
>>> Your are leaking to user space part of kernel stack, if (i <
>>> SOCK_USR_ZC_INFO_MAX)
>>>
>>
>> Agree, I should do memset to clear the array.
>
> Or copy only the part that has been initialized, struct_size() might help ...
Thanks for the suggestions, I will update in the next version :)
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 20:52 ` [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG zijianzhang
2024-04-09 21:18 ` Willem de Bruijn
2024-04-09 21:18 ` Eric Dumazet
@ 2024-04-09 21:23 ` Eric Dumazet
2024-04-10 0:11 ` [External] " Zijian Zhang
2024-04-10 9:18 ` kernel test robot
` (2 subsequent siblings)
5 siblings, 1 reply; 24+ messages in thread
From: Eric Dumazet @ 2024-04-09 21:23 UTC (permalink / raw)
To: zijianzhang
Cc: netdev, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu
On Tue, Apr 9, 2024 at 10:53 PM <zijianzhang@bytedance.com> wrote:
>
> From: Zijian Zhang <zijianzhang@bytedance.com>
>
> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
> However, zerocopy is not a free lunch. Apart from the management of user
> pages, the combination of poll + recvmsg to receive notifications incurs
> unignorable overhead in the applications. The overhead of such sometimes
> might be more than the CPU savings from zerocopy. We try to solve this
> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
> This new mechanism aims to reduce the overhead associated with receiving
> notifications by embedding them directly into user arguments passed with
> each sendmsg control message. By doing so, we can significantly reduce
> the complexity and overhead for managing notifications. In an ideal
> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
> flag, and the notification will be delivered as soon as possible.
>
> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
> ---
> include/linux/skbuff.h | 7 +-
> include/linux/socket.h | 1 +
> include/linux/tcp.h | 3 +
> include/linux/udp.h | 3 +
> include/net/sock.h | 17 +++
> include/net/udp.h | 1 +
> include/uapi/asm-generic/socket.h | 2 +
> include/uapi/linux/socket.h | 17 +++
...
> +
> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
> +{
> + spin_lock_init(&q->lock);
> + INIT_LIST_HEAD(&q->head);
> +}
> +
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index e767721b3a58..6254d0eef3af 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -462,6 +462,8 @@ void tcp_init_sock(struct sock *sk)
>
> set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
> sk_sockets_allocated_inc(sk);
> +
> + tx_message_zcopy_queue_init(&tp->tx_zcopy_queue);
> }
FYI, tcp_init_sock() is not called for passive sockets.
syzbot would quite easily crash if zerovopy is used after accept()...
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [External] Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 21:23 ` Eric Dumazet
@ 2024-04-10 0:11 ` Zijian Zhang
0 siblings, 0 replies; 24+ messages in thread
From: Zijian Zhang @ 2024-04-10 0:11 UTC (permalink / raw)
To: Eric Dumazet
Cc: netdev, willemdebruijn.kernel, davem, kuba, cong.wang,
xiaochun.lu
On 4/9/24 2:23 PM, Eric Dumazet wrote:
> On Tue, Apr 9, 2024 at 10:53 PM <zijianzhang@bytedance.com> wrote:
>>
>> From: Zijian Zhang <zijianzhang@bytedance.com>
>>
>> The MSG_ZEROCOPY flag enables copy avoidance for socket send calls.
>> However, zerocopy is not a free lunch. Apart from the management of user
>> pages, the combination of poll + recvmsg to receive notifications incurs
>> unignorable overhead in the applications. The overhead of such sometimes
>> might be more than the CPU savings from zerocopy. We try to solve this
>> problem with a new option for TCP and UDP, MSG_ZEROCOPY_UARG.
>> This new mechanism aims to reduce the overhead associated with receiving
>> notifications by embedding them directly into user arguments passed with
>> each sendmsg control message. By doing so, we can significantly reduce
>> the complexity and overhead for managing notifications. In an ideal
>> pattern, the user will keep calling sendmsg with MSG_ZEROCOPY_UARG
>> flag, and the notification will be delivered as soon as possible.
>>
>> Signed-off-by: Zijian Zhang <zijianzhang@bytedance.com>
>> Signed-off-by: Xiaochun Lu <xiaochun.lu@bytedance.com>
>> ---
>> include/linux/skbuff.h | 7 +-
>> include/linux/socket.h | 1 +
>> include/linux/tcp.h | 3 +
>> include/linux/udp.h | 3 +
>> include/net/sock.h | 17 +++
>> include/net/udp.h | 1 +
>> include/uapi/asm-generic/socket.h | 2 +
>> include/uapi/linux/socket.h | 17 +++
>
> ...
>
>> +
>> +static inline void tx_message_zcopy_queue_init(struct tx_msg_zcopy_queue *q)
>> +{
>> + spin_lock_init(&q->lock);
>> + INIT_LIST_HEAD(&q->head);
>> +}
>> +
>>
>
>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>> index e767721b3a58..6254d0eef3af 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -462,6 +462,8 @@ void tcp_init_sock(struct sock *sk)
>>
>> set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
>> sk_sockets_allocated_inc(sk);
>> +
>> + tx_message_zcopy_queue_init(&tp->tx_zcopy_queue);
>> }
>
>
> FYI, tcp_init_sock() is not called for passive sockets.
>
> syzbot would quite easily crash if zerovopy is used after accept()...
Thanks for the info, I will reuse error queue in the next patch set and
this line of code will be deleted.
^ permalink raw reply [flat|nested] 24+ messages in thread
* Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 20:52 ` [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG zijianzhang
` (2 preceding siblings ...)
2024-04-09 21:23 ` Eric Dumazet
@ 2024-04-10 9:18 ` kernel test robot
2024-04-10 12:11 ` kernel test robot
2024-04-10 15:22 ` kernel test robot
5 siblings, 0 replies; 24+ messages in thread
From: kernel test robot @ 2024-04-10 9:18 UTC (permalink / raw)
To: zijianzhang, netdev
Cc: oe-kbuild-all, edumazet, willemdebruijn.kernel, davem, kuba,
cong.wang, xiaochun.lu, Zijian Zhang
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on net-next/main]
url: https://github.com/intel-lab-lkp/linux/commits/zijianzhang-bytedance-com/sock-add-MSG_ZEROCOPY_UARG/20240410-045616
base: net-next/main
patch link: https://lore.kernel.org/r/20240409205300.1346681-2-zijianzhang%40bytedance.com
patch subject: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
config: alpha-defconfig (https://download.01.org/0day-ci/archive/20240410/202404101756.S6ltBayX-lkp@intel.com/config)
compiler: alpha-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240410/202404101756.S6ltBayX-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404101756.S6ltBayX-lkp@intel.com/
All errors (new ones prefixed by >>):
net/core/sock.c: In function '__sock_cmsg_send':
>> net/core/sock.c:2845:14: error: 'SO_ZEROCOPY_NOTIFICATION' undeclared (first use in this function)
2845 | case SO_ZEROCOPY_NOTIFICATION:
| ^~~~~~~~~~~~~~~~~~~~~~~~
net/core/sock.c:2845:14: note: each undeclared identifier is reported only once for each function it appears in
vim +/SO_ZEROCOPY_NOTIFICATION +2845 net/core/sock.c
2807
2808 int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
2809 struct sockcm_cookie *sockc)
2810 {
2811 u32 tsflags;
2812
2813 switch (cmsg->cmsg_type) {
2814 case SO_MARK:
2815 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&
2816 !ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
2817 return -EPERM;
2818 if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
2819 return -EINVAL;
2820 sockc->mark = *(u32 *)CMSG_DATA(cmsg);
2821 break;
2822 case SO_TIMESTAMPING_OLD:
2823 case SO_TIMESTAMPING_NEW:
2824 if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
2825 return -EINVAL;
2826
2827 tsflags = *(u32 *)CMSG_DATA(cmsg);
2828 if (tsflags & ~SOF_TIMESTAMPING_TX_RECORD_MASK)
2829 return -EINVAL;
2830
2831 sockc->tsflags &= ~SOF_TIMESTAMPING_TX_RECORD_MASK;
2832 sockc->tsflags |= tsflags;
2833 break;
2834 case SCM_TXTIME:
2835 if (!sock_flag(sk, SOCK_TXTIME))
2836 return -EINVAL;
2837 if (cmsg->cmsg_len != CMSG_LEN(sizeof(u64)))
2838 return -EINVAL;
2839 sockc->transmit_time = get_unaligned((u64 *)CMSG_DATA(cmsg));
2840 break;
2841 /* SCM_RIGHTS and SCM_CREDENTIALS are semantically in SOL_UNIX. */
2842 case SCM_RIGHTS:
2843 case SCM_CREDENTIALS:
2844 break;
> 2845 case SO_ZEROCOPY_NOTIFICATION:
2846 if (sock_flag(sk, SOCK_ZEROCOPY)) {
2847 int i = 0;
2848 struct tx_usr_zcopy_info sys_zcopy_info;
2849 struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
2850 struct tx_msg_zcopy_queue *zcopy_queue;
2851 struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
2852 unsigned long flags;
2853
2854 if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
2855 return -EINVAL;
2856
2857 if (sk_is_tcp(sk))
2858 zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
2859 else if (sk_is_udp(sk))
2860 zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
2861 else
2862 return -EINVAL;
2863
2864 spin_lock_irqsave(&zcopy_queue->lock, flags);
2865 list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
2866 sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
2867 sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
2868 sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
2869 list_del(&zcopy_node_p->node);
2870 zcopy_node_ps[i++] = zcopy_node_p;
2871 if (i == SOCK_USR_ZC_INFO_MAX)
2872 break;
2873 }
2874 spin_unlock_irqrestore(&zcopy_queue->lock, flags);
2875
2876 if (i > 0) {
2877 sys_zcopy_info.length = i;
2878 if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
2879 &sys_zcopy_info,
2880 sizeof(sys_zcopy_info))
2881 )) {
2882 spin_lock_irqsave(&zcopy_queue->lock, flags);
2883 while (i > 0)
2884 list_add(&zcopy_node_ps[--i]->node,
2885 &zcopy_queue->head);
2886 spin_unlock_irqrestore(&zcopy_queue->lock, flags);
2887 return -EFAULT;
2888 }
2889
2890 while (i > 0)
2891 consume_skb(zcopy_node_ps[--i]->skb);
2892 }
2893 }
2894 break;
2895 default:
2896 return -EINVAL;
2897 }
2898 return 0;
2899 }
2900 EXPORT_SYMBOL(__sock_cmsg_send);
2901
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 20:52 ` [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG zijianzhang
` (3 preceding siblings ...)
2024-04-10 9:18 ` kernel test robot
@ 2024-04-10 12:11 ` kernel test robot
2024-04-10 15:22 ` kernel test robot
5 siblings, 0 replies; 24+ messages in thread
From: kernel test robot @ 2024-04-10 12:11 UTC (permalink / raw)
To: zijianzhang, netdev
Cc: oe-kbuild-all, edumazet, willemdebruijn.kernel, davem, kuba,
cong.wang, xiaochun.lu, Zijian Zhang
Hi,
kernel test robot noticed the following build warnings:
[auto build test WARNING on net-next/main]
url: https://github.com/intel-lab-lkp/linux/commits/zijianzhang-bytedance-com/sock-add-MSG_ZEROCOPY_UARG/20240410-045616
base: net-next/main
patch link: https://lore.kernel.org/r/20240409205300.1346681-2-zijianzhang%40bytedance.com
patch subject: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
config: i386-randconfig-061-20240410 (https://download.01.org/0day-ci/archive/20240410/202404101954.FBZojOXG-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240410/202404101954.FBZojOXG-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404101954.FBZojOXG-lkp@intel.com/
sparse warnings: (new ones prefixed by >>)
>> net/core/sock.c:2878:37: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void [noderef] __user *to @@ got void * @@
net/core/sock.c:2878:37: sparse: expected void [noderef] __user *to
net/core/sock.c:2878:37: sparse: got void *
net/core/sock.c:2393:9: sparse: sparse: context imbalance in 'sk_clone_lock' - wrong count at exit
net/core/sock.c:2397:6: sparse: sparse: context imbalance in 'sk_free_unlock_clone' - unexpected unlock
net/core/sock.c:4083:13: sparse: sparse: context imbalance in 'proto_seq_start' - wrong count at exit
net/core/sock.c:4095:13: sparse: sparse: context imbalance in 'proto_seq_stop' - wrong count at exit
vim +2878 net/core/sock.c
2807
2808 int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
2809 struct sockcm_cookie *sockc)
2810 {
2811 u32 tsflags;
2812
2813 switch (cmsg->cmsg_type) {
2814 case SO_MARK:
2815 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&
2816 !ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
2817 return -EPERM;
2818 if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
2819 return -EINVAL;
2820 sockc->mark = *(u32 *)CMSG_DATA(cmsg);
2821 break;
2822 case SO_TIMESTAMPING_OLD:
2823 case SO_TIMESTAMPING_NEW:
2824 if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
2825 return -EINVAL;
2826
2827 tsflags = *(u32 *)CMSG_DATA(cmsg);
2828 if (tsflags & ~SOF_TIMESTAMPING_TX_RECORD_MASK)
2829 return -EINVAL;
2830
2831 sockc->tsflags &= ~SOF_TIMESTAMPING_TX_RECORD_MASK;
2832 sockc->tsflags |= tsflags;
2833 break;
2834 case SCM_TXTIME:
2835 if (!sock_flag(sk, SOCK_TXTIME))
2836 return -EINVAL;
2837 if (cmsg->cmsg_len != CMSG_LEN(sizeof(u64)))
2838 return -EINVAL;
2839 sockc->transmit_time = get_unaligned((u64 *)CMSG_DATA(cmsg));
2840 break;
2841 /* SCM_RIGHTS and SCM_CREDENTIALS are semantically in SOL_UNIX. */
2842 case SCM_RIGHTS:
2843 case SCM_CREDENTIALS:
2844 break;
2845 case SO_ZEROCOPY_NOTIFICATION:
2846 if (sock_flag(sk, SOCK_ZEROCOPY)) {
2847 int i = 0;
2848 struct tx_usr_zcopy_info sys_zcopy_info;
2849 struct tx_msg_zcopy_node *zcopy_node_p, *tmp;
2850 struct tx_msg_zcopy_queue *zcopy_queue;
2851 struct tx_msg_zcopy_node *zcopy_node_ps[SOCK_USR_ZC_INFO_MAX];
2852 unsigned long flags;
2853
2854 if (cmsg->cmsg_len != CMSG_LEN(sizeof(void *)))
2855 return -EINVAL;
2856
2857 if (sk_is_tcp(sk))
2858 zcopy_queue = &tcp_sk(sk)->tx_zcopy_queue;
2859 else if (sk_is_udp(sk))
2860 zcopy_queue = &udp_sk(sk)->tx_zcopy_queue;
2861 else
2862 return -EINVAL;
2863
2864 spin_lock_irqsave(&zcopy_queue->lock, flags);
2865 list_for_each_entry_safe(zcopy_node_p, tmp, &zcopy_queue->head, node) {
2866 sys_zcopy_info.info[i].lo = zcopy_node_p->info.lo;
2867 sys_zcopy_info.info[i].hi = zcopy_node_p->info.hi;
2868 sys_zcopy_info.info[i].zerocopy = zcopy_node_p->info.zerocopy;
2869 list_del(&zcopy_node_p->node);
2870 zcopy_node_ps[i++] = zcopy_node_p;
2871 if (i == SOCK_USR_ZC_INFO_MAX)
2872 break;
2873 }
2874 spin_unlock_irqrestore(&zcopy_queue->lock, flags);
2875
2876 if (i > 0) {
2877 sys_zcopy_info.length = i;
> 2878 if (unlikely(copy_to_user(*(void **)CMSG_DATA(cmsg),
2879 &sys_zcopy_info,
2880 sizeof(sys_zcopy_info))
2881 )) {
2882 spin_lock_irqsave(&zcopy_queue->lock, flags);
2883 while (i > 0)
2884 list_add(&zcopy_node_ps[--i]->node,
2885 &zcopy_queue->head);
2886 spin_unlock_irqrestore(&zcopy_queue->lock, flags);
2887 return -EFAULT;
2888 }
2889
2890 while (i > 0)
2891 consume_skb(zcopy_node_ps[--i]->skb);
2892 }
2893 }
2894 break;
2895 default:
2896 return -EINVAL;
2897 }
2898 return 0;
2899 }
2900 EXPORT_SYMBOL(__sock_cmsg_send);
2901
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 24+ messages in thread* Re: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
2024-04-09 20:52 ` [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG zijianzhang
` (4 preceding siblings ...)
2024-04-10 12:11 ` kernel test robot
@ 2024-04-10 15:22 ` kernel test robot
5 siblings, 0 replies; 24+ messages in thread
From: kernel test robot @ 2024-04-10 15:22 UTC (permalink / raw)
To: zijianzhang, netdev
Cc: oe-kbuild-all, edumazet, willemdebruijn.kernel, davem, kuba,
cong.wang, xiaochun.lu, Zijian Zhang
Hi,
kernel test robot noticed the following build errors:
[auto build test ERROR on net-next/main]
url: https://github.com/intel-lab-lkp/linux/commits/zijianzhang-bytedance-com/sock-add-MSG_ZEROCOPY_UARG/20240410-045616
base: net-next/main
patch link: https://lore.kernel.org/r/20240409205300.1346681-2-zijianzhang%40bytedance.com
patch subject: [PATCH net-next 1/3] sock: add MSG_ZEROCOPY_UARG
config: x86_64-randconfig-r081-20240410 (https://download.01.org/0day-ci/archive/20240410/202404102247.qzN9N0Il-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240410/202404102247.qzN9N0Il-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202404102247.qzN9N0Il-lkp@intel.com/
All errors (new ones prefixed by >>):
In file included from <built-in>:1:
In file included from ./usr/include/linux/un.h:5:
>> usr/include/linux/socket.h:45:2: error: unknown type name '__u32'
45 | __u32 lo;
| ^
usr/include/linux/socket.h:46:2: error: unknown type name '__u32'
46 | __u32 hi;
| ^
>> usr/include/linux/socket.h:47:2: error: unknown type name '__u8'
47 | __u8 zerocopy;
| ^
3 errors generated.
--
In file included from <built-in>:1:
>> ./usr/include/linux/socket.h:45:2: error: unknown type name '__u32'
45 | __u32 lo;
| ^
./usr/include/linux/socket.h:46:2: error: unknown type name '__u32'
46 | __u32 hi;
| ^
>> ./usr/include/linux/socket.h:47:2: error: unknown type name '__u8'
47 | __u8 zerocopy;
| ^
3 errors generated.
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 24+ messages in thread