Commit 5cf4a853 authored by Vincent Whitchurch's avatar Vincent Whitchurch Committed by David S. Miller

tcp: really ignore MSG_ZEROCOPY if no SO_ZEROCOPY

According to the documentation in msg_zerocopy.rst, the SO_ZEROCOPY
flag was introduced because send(2) ignores unknown message flags and
any legacy application which was accidentally passing the equivalent of
MSG_ZEROCOPY earlier should not see any new behaviour.

Before commit f214f915 ("tcp: enable MSG_ZEROCOPY"), a send(2) call
which passed the equivalent of MSG_ZEROCOPY without setting SO_ZEROCOPY
would succeed.  However, after that commit, it fails with -ENOBUFS.  So
it appears that the SO_ZEROCOPY flag fails to fulfill its intended
purpose.  Fix it.

Fixes: f214f915 ("tcp: enable MSG_ZEROCOPY")
Signed-off-by: default avatarVincent Whitchurch <vincent.whitchurch@axis.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a162c351
...@@ -939,9 +939,6 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size) ...@@ -939,9 +939,6 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
WARN_ON_ONCE(!in_task()); WARN_ON_ONCE(!in_task());
if (!sock_flag(sk, SOCK_ZEROCOPY))
return NULL;
skb = sock_omalloc(sk, 0, GFP_KERNEL); skb = sock_omalloc(sk, 0, GFP_KERNEL);
if (!skb) if (!skb)
return NULL; return NULL;
......
...@@ -1185,7 +1185,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) ...@@ -1185,7 +1185,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
flags = msg->msg_flags; flags = msg->msg_flags;
if (flags & MSG_ZEROCOPY && size) { if (flags & MSG_ZEROCOPY && size && sock_flag(sk, SOCK_ZEROCOPY)) {
if (sk->sk_state != TCP_ESTABLISHED) { if (sk->sk_state != TCP_ESTABLISHED) {
err = -EINVAL; err = -EINVAL;
goto out_err; goto out_err;
......
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