* [PATCH AUTOSEL 6.14 20/54] mptcp: move the whole rx path under msk socket lock protection
[not found] <20250403190209.2675485-1-sashal@kernel.org>
@ 2025-04-03 19:01 ` Sasha Levin
2025-04-08 17:18 ` Matthieu Baerts
2025-04-10 11:05 ` Matthieu Baerts
0 siblings, 2 replies; 5+ messages in thread
From: Sasha Levin @ 2025-04-03 19:01 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Paolo Abeni, Mat Martineau, Matthieu Baerts, Jakub Kicinski,
Sasha Levin, davem, edumazet, netdev, mptcp
From: Paolo Abeni <pabeni@redhat.com>
[ Upstream commit bc68b0efa1bf923cef1294a631d8e7416c7e06e4 ]
After commit c2e6048fa1cf ("mptcp: fix race in release_cb") we can
move the whole MPTCP rx path under the socket lock leveraging the
release_cb.
We can drop a bunch of spin_lock pairs in the receive functions, use
a single receive queue and invoke __mptcp_move_skbs only when subflows
ask for it.
This will allow more cleanup in the next patch.
Some changes are worth specific mention:
The msk rcvbuf update now always happens under both the msk and the
subflow socket lock: we can drop a bunch of ONCE annotation and
consolidate the checks.
When the skbs move is delayed at msk release callback time, even the
msk rcvbuf update is delayed; additionally take care of such action in
__mptcp_move_skbs().
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250218-net-next-mptcp-rx-path-refactor-v1-3-4a47d90d7998@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mptcp/fastopen.c | 1 +
net/mptcp/protocol.c | 123 ++++++++++++++++++++-----------------------
net/mptcp/protocol.h | 2 +-
3 files changed, 60 insertions(+), 66 deletions(-)
diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c
index a29ff901df758..305f4c48ec158 100644
--- a/net/mptcp/fastopen.c
+++ b/net/mptcp/fastopen.c
@@ -49,6 +49,7 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subf
MPTCP_SKB_CB(skb)->has_rxtstamp = TCP_SKB_CB(skb)->has_rxtstamp;
mptcp_data_lock(sk);
+ DEBUG_NET_WARN_ON_ONCE(sock_owned_by_user_nocheck(sk));
mptcp_set_owner_r(skb, sk);
__skb_queue_tail(&sk->sk_receive_queue, skb);
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 6bd8190474706..3117c06f5362e 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -643,18 +643,6 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
bool more_data_avail;
struct tcp_sock *tp;
bool done = false;
- int sk_rbuf;
-
- sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
-
- if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
- int ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
-
- if (unlikely(ssk_rbuf > sk_rbuf)) {
- WRITE_ONCE(sk->sk_rcvbuf, ssk_rbuf);
- sk_rbuf = ssk_rbuf;
- }
- }
pr_debug("msk=%p ssk=%p\n", msk, ssk);
tp = tcp_sk(ssk);
@@ -722,7 +710,7 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
WRITE_ONCE(tp->copied_seq, seq);
more_data_avail = mptcp_subflow_data_available(ssk);
- if (atomic_read(&sk->sk_rmem_alloc) > sk_rbuf) {
+ if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) {
done = true;
break;
}
@@ -846,11 +834,30 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, struct sock *ssk)
return moved > 0;
}
+static void __mptcp_rcvbuf_update(struct sock *sk, struct sock *ssk)
+{
+ if (unlikely(ssk->sk_rcvbuf > sk->sk_rcvbuf))
+ WRITE_ONCE(sk->sk_rcvbuf, ssk->sk_rcvbuf);
+}
+
+static void __mptcp_data_ready(struct sock *sk, struct sock *ssk)
+{
+ struct mptcp_sock *msk = mptcp_sk(sk);
+
+ __mptcp_rcvbuf_update(sk, ssk);
+
+ /* over limit? can't append more skbs to msk, Also, no need to wake-up*/
+ if (__mptcp_rmem(sk) > sk->sk_rcvbuf)
+ return;
+
+ /* Wake-up the reader only for in-sequence data */
+ if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk))
+ sk->sk_data_ready(sk);
+}
+
void mptcp_data_ready(struct sock *sk, struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
- struct mptcp_sock *msk = mptcp_sk(sk);
- int sk_rbuf, ssk_rbuf;
/* The peer can send data while we are shutting down this
* subflow at msk destruction time, but we must avoid enqueuing
@@ -859,19 +866,11 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk)
if (unlikely(subflow->disposable))
return;
- ssk_rbuf = READ_ONCE(ssk->sk_rcvbuf);
- sk_rbuf = READ_ONCE(sk->sk_rcvbuf);
- if (unlikely(ssk_rbuf > sk_rbuf))
- sk_rbuf = ssk_rbuf;
-
- /* over limit? can't append more skbs to msk, Also, no need to wake-up*/
- if (__mptcp_rmem(sk) > sk_rbuf)
- return;
-
- /* Wake-up the reader only for in-sequence data */
mptcp_data_lock(sk);
- if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk))
- sk->sk_data_ready(sk);
+ if (!sock_owned_by_user(sk))
+ __mptcp_data_ready(sk, ssk);
+ else
+ __set_bit(MPTCP_DEQUEUE, &mptcp_sk(sk)->cb_flags);
mptcp_data_unlock(sk);
}
@@ -1944,16 +1943,17 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied);
-static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
+static int __mptcp_recvmsg_mskq(struct sock *sk,
struct msghdr *msg,
size_t len, int flags,
struct scm_timestamping_internal *tss,
int *cmsg_flags)
{
+ struct mptcp_sock *msk = mptcp_sk(sk);
struct sk_buff *skb, *tmp;
int copied = 0;
- skb_queue_walk_safe(&msk->receive_queue, skb, tmp) {
+ skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp) {
u32 offset = MPTCP_SKB_CB(skb)->offset;
u32 data_len = skb->len - offset;
u32 count = min_t(size_t, len - copied, data_len);
@@ -1988,7 +1988,7 @@ static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
/* we will bulk release the skb memory later */
skb->destructor = NULL;
WRITE_ONCE(msk->rmem_released, msk->rmem_released + skb->truesize);
- __skb_unlink(skb, &msk->receive_queue);
+ __skb_unlink(skb, &sk->sk_receive_queue);
__kfree_skb(skb);
msk->bytes_consumed += count;
}
@@ -2113,54 +2113,46 @@ static void __mptcp_update_rmem(struct sock *sk)
WRITE_ONCE(msk->rmem_released, 0);
}
-static void __mptcp_splice_receive_queue(struct sock *sk)
+static bool __mptcp_move_skbs(struct sock *sk)
{
+ struct mptcp_subflow_context *subflow;
struct mptcp_sock *msk = mptcp_sk(sk);
-
- skb_queue_splice_tail_init(&sk->sk_receive_queue, &msk->receive_queue);
-}
-
-static bool __mptcp_move_skbs(struct mptcp_sock *msk)
-{
- struct sock *sk = (struct sock *)msk;
unsigned int moved = 0;
bool ret, done;
+ /* verify we can move any data from the subflow, eventually updating */
+ if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK))
+ mptcp_for_each_subflow(msk, subflow)
+ __mptcp_rcvbuf_update(sk, subflow->tcp_sock);
+
+ if (__mptcp_rmem(sk) > sk->sk_rcvbuf)
+ return false;
+
do {
struct sock *ssk = mptcp_subflow_recv_lookup(msk);
bool slowpath;
- /* we can have data pending in the subflows only if the msk
- * receive buffer was full at subflow_data_ready() time,
- * that is an unlikely slow path.
- */
- if (likely(!ssk))
+ if (unlikely(!ssk))
break;
slowpath = lock_sock_fast(ssk);
- mptcp_data_lock(sk);
__mptcp_update_rmem(sk);
done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved);
- mptcp_data_unlock(sk);
if (unlikely(ssk->sk_err))
__mptcp_error_report(sk);
unlock_sock_fast(ssk, slowpath);
} while (!done);
- /* acquire the data lock only if some input data is pending */
ret = moved > 0;
if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) ||
- !skb_queue_empty_lockless(&sk->sk_receive_queue)) {
- mptcp_data_lock(sk);
+ !skb_queue_empty(&sk->sk_receive_queue)) {
__mptcp_update_rmem(sk);
ret |= __mptcp_ofo_queue(msk);
- __mptcp_splice_receive_queue(sk);
- mptcp_data_unlock(sk);
}
if (ret)
mptcp_check_data_fin((struct sock *)msk);
- return !skb_queue_empty(&msk->receive_queue);
+ return ret;
}
static unsigned int mptcp_inq_hint(const struct sock *sk)
@@ -2168,7 +2160,7 @@ static unsigned int mptcp_inq_hint(const struct sock *sk)
const struct mptcp_sock *msk = mptcp_sk(sk);
const struct sk_buff *skb;
- skb = skb_peek(&msk->receive_queue);
+ skb = skb_peek(&sk->sk_receive_queue);
if (skb) {
u64 hint_val = READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq;
@@ -2214,7 +2206,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
while (copied < len) {
int err, bytes_read;
- bytes_read = __mptcp_recvmsg_mskq(msk, msg, len - copied, flags, &tss, &cmsg_flags);
+ bytes_read = __mptcp_recvmsg_mskq(sk, msg, len - copied, flags, &tss, &cmsg_flags);
if (unlikely(bytes_read < 0)) {
if (!copied)
copied = bytes_read;
@@ -2223,7 +2215,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
copied += bytes_read;
- if (skb_queue_empty(&msk->receive_queue) && __mptcp_move_skbs(msk))
+ if (skb_queue_empty(&sk->sk_receive_queue) && __mptcp_move_skbs(sk))
continue;
/* only the MPTCP socket status is relevant here. The exit
@@ -2249,7 +2241,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
/* race breaker: the shutdown could be after the
* previous receive queue check
*/
- if (__mptcp_move_skbs(msk))
+ if (__mptcp_move_skbs(sk))
continue;
break;
}
@@ -2293,9 +2285,8 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
}
}
- pr_debug("msk=%p rx queue empty=%d:%d copied=%d\n",
- msk, skb_queue_empty_lockless(&sk->sk_receive_queue),
- skb_queue_empty(&msk->receive_queue), copied);
+ pr_debug("msk=%p rx queue empty=%d copied=%d\n",
+ msk, skb_queue_empty(&sk->sk_receive_queue), copied);
release_sock(sk);
return copied;
@@ -2822,7 +2813,6 @@ static void __mptcp_init_sock(struct sock *sk)
INIT_LIST_HEAD(&msk->join_list);
INIT_LIST_HEAD(&msk->rtx_queue);
INIT_WORK(&msk->work, mptcp_worker);
- __skb_queue_head_init(&msk->receive_queue);
msk->out_of_order_queue = RB_ROOT;
msk->first_pending = NULL;
WRITE_ONCE(msk->rmem_fwd_alloc, 0);
@@ -3405,12 +3395,8 @@ void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
mptcp_for_each_subflow_safe(msk, subflow, tmp)
__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow), subflow, flags);
- /* move to sk_receive_queue, sk_stream_kill_queues will purge it */
- mptcp_data_lock(sk);
- skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
__skb_queue_purge(&sk->sk_receive_queue);
skb_rbtree_purge(&msk->out_of_order_queue);
- mptcp_data_unlock(sk);
/* move all the rx fwd alloc into the sk_mem_reclaim_final in
* inet_sock_destruct() will dispose it
@@ -3453,7 +3439,8 @@ void __mptcp_check_push(struct sock *sk, struct sock *ssk)
#define MPTCP_FLAGS_PROCESS_CTX_NEED (BIT(MPTCP_PUSH_PENDING) | \
BIT(MPTCP_RETRANSMIT) | \
- BIT(MPTCP_FLUSH_JOIN_LIST))
+ BIT(MPTCP_FLUSH_JOIN_LIST) | \
+ BIT(MPTCP_DEQUEUE))
/* processes deferred events and flush wmem */
static void mptcp_release_cb(struct sock *sk)
@@ -3487,6 +3474,11 @@ static void mptcp_release_cb(struct sock *sk)
__mptcp_push_pending(sk, 0);
if (flags & BIT(MPTCP_RETRANSMIT))
__mptcp_retrans(sk);
+ if ((flags & BIT(MPTCP_DEQUEUE)) && __mptcp_move_skbs(sk)) {
+ /* notify ack seq update */
+ mptcp_cleanup_rbuf(msk, 0);
+ sk->sk_data_ready(sk);
+ }
cond_resched();
spin_lock_bh(&sk->sk_lock.slock);
@@ -3724,7 +3716,8 @@ static int mptcp_ioctl(struct sock *sk, int cmd, int *karg)
return -EINVAL;
lock_sock(sk);
- __mptcp_move_skbs(msk);
+ if (__mptcp_move_skbs(sk))
+ mptcp_cleanup_rbuf(msk, 0);
*karg = mptcp_inq_hint(sk);
release_sock(sk);
break;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index ad21925af0612..2f4e3188cf3b2 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -124,6 +124,7 @@
#define MPTCP_FLUSH_JOIN_LIST 5
#define MPTCP_SYNC_STATE 6
#define MPTCP_SYNC_SNDBUF 7
+#define MPTCP_DEQUEUE 8
struct mptcp_skb_cb {
u64 map_seq;
@@ -324,7 +325,6 @@ struct mptcp_sock {
struct work_struct work;
struct sk_buff *ooo_last_skb;
struct rb_root out_of_order_queue;
- struct sk_buff_head receive_queue;
struct list_head conn_list;
struct list_head rtx_queue;
struct mptcp_data_frag *first_pending;
--
2.39.5
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