With TCP Fastopen we can have the following cases, which could also
use MSG_ZEROCOPY flag with send() and sendto():
* sendto() + MSG_FASTOPEN flag, sk state can be in TCP_CLOSE at
the start of tcp_sendmsg()
* set socket option TCP_FASTOPEN_CONNECT, then connect()
and send(), sk state in TCP_SYN_SENT
Currently, both cases with tcp_sendmsg() and MSG_ZEROCOPY flag results
to EINVAL error, because of the check for TCP_ESTABLISHED sk state in
the beginning of tcp_sendmsg().
Both conditions require two more checks there: !tp->fastopen_connect
and !(flags & MSG_FASTOPEN). It looks like we could remove the original
check altogether for this unlikely event instead. That way tcp_sendmsg()
without TFO should fail with EPIPE on sk_stream_wait_connect(), as
before the introduction of MSG_ZEROCOPY there. And work smoothly for
the TFO cases.
Fixes: f214f915e7db ("tcp: enable MSG_ZEROCOPY")
Signed-off-by: Alexey Kodanev <alexey.koda...@oracle.com>
---
Is there something that I've overlooked and we can't use it here, and
we should handle this type of error, while using sendto() + TFO,
in userspace?
net/ipv4/tcp.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9225610..768f02c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1193,11 +1193,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr
*msg, size_t size)
flags = msg->msg_flags;
if (flags & MSG_ZEROCOPY && size) {
- if (sk->sk_state != TCP_ESTABLISHED) {
- err = -EINVAL;
- goto out_err;
- }
-
skb = tcp_write_queue_tail(sk);
uarg = sock_zerocopy_realloc(sk, size, skb_zcopy(skb));
if (!uarg) {
--
1.8.3.1
