[PATCH 6.0 08/20] net: flag sockets supporting msghdr originated zerocopy

Greg Kroah-Hartman
2022-10-24T11:33:46Z

From: Pavel Begunkov <asml.silence@gmail.com>

commit e993ffe3da4bcddea0536b03be1031bf35cd8d85 upstream.

We need an efficient way in io_uring to check whether a socket supports
zerocopy with msghdr provided ubuf_info. Add a new flag into the struct
socket flags fields.

Cc: <stable@vger.kernel.org> # 6.0
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/3dafafab822b1c66308bb58a0ac738b1e3f53f74.1666346426.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/net.h | 1 +
net/ipv4/tcp.c | 1 +
net/ipv4/udp.c | 1 +
3 files changed, 3 insertions(+)

--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -41,6 +41,7 @@ struct net;
#define SOCK_NOSPACE 2
#define SOCK_PASSCRED 3
#define SOCK_PASSSEC 4
+#define SOCK_SUPPORT_ZC 5

#ifndef ARCH_HAS_SOCKET_TYPES
/**
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -457,6 +457,7 @@ void tcp_init_sock(struct sock *sk)
WRITE_ONCE(sk->sk_sndbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[1]));
WRITE_ONCE(sk->sk_rcvbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[1]));

+ set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
sk_sockets_allocated_inc(sk);
}
EXPORT_SYMBOL(tcp_init_sock);
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1620,6 +1620,7 @@ int udp_init_sock(struct sock *sk)
{
skb_queue_head_init(&udp_sk(sk)->reader_queue);
sk->sk_destruct = udp_destruct_sock;
+ set_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags);
return 0;
}
EXPORT_SYMBOL_GPL(udp_init_sock);