On Sat, Aug 17, 2019 at 12:26 AM Eric Dumazet <eduma...@google.com> wrote:
>
> As Jason Baron explained in commit 790ba4566c1a ("tcp: set SOCK_NOSPACE
> under memory pressure"), it is crucial we properly set SOCK_NOSPACE
> when needed.
>
> However, Jason patch had a bug, because the 'nonblocking' status
> as far as sk_stream_wait_memory() is concerned is governed
> by MSG_DONTWAIT flag passed at sendmsg() time :
>
> long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
>
> So it is very possible that tcp sendmsg() calls sk_stream_wait_memory(),
> and that sk_stream_wait_memory() returns -EAGAIN with SOCK_NOSPACE
> cleared, if sk->sk_sndtimeo has been set to a small (but not zero)
> value.
>
> This patch removes the 'noblock' variable since we must always
> set SOCK_NOSPACE if -EAGAIN is returned.
>
> It also renames the do_nonblock label since we might reach this
> code path even if we were in blocking mode.
>
> Fixes: 790ba4566c1a ("tcp: set SOCK_NOSPACE under memory pressure")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Cc: Jason Baron <jba...@akamai.com>
> Reported-by: Vladimir Rutsky <rut...@google.com>
> ---
> net/core/stream.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
Acked-by: Neal Cardwell <ncardw...@google.com>
Thanks, Eric!
neal
