[PATCH for-6.1 1/3] net: flag sockets supporting msghdr originated zerocopy

[Pavel Begunkov <asml.silence@gmail.com>]

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>
---
 include/linux/net.h | 1 +
 net/ipv4/tcp.c      | 1 +
 net/ipv4/udp.c      | 1 +
 3 files changed, 3 insertions(+)

diff --git a/include/linux/net.h b/include/linux/net.h
index 711c3593c3b8..18d942bbdf6e 100644
--- 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
 /**
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0c51abeee172..aeb7b9eaddc7 100644
--- 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);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index d63118ce5900..03616fc5162c 100644
--- 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);
-- 
2.38.0