Hi Stefano, On 02.08.2023 10:46, Stefano Garzarella wrote: > On Tue, Aug 01, 2023 at 05:17:26PM +0300, Arseniy Krasnov wrote: >> POSIX requires to send SIGPIPE on write to SOCK_STREAM socket which was >> shutdowned with SHUT_WR flag or its peer was shutdowned with SHUT_RD >> flag. Also we must not send SIGPIPE if MSG_NOSIGNAL flag is set. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx> >> --- >> net/vmw_vsock/af_vsock.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c >> index 020cf17ab7e4..013b65241b65 100644 >> --- a/net/vmw_vsock/af_vsock.c >> +++ b/net/vmw_vsock/af_vsock.c >> @@ -1921,6 +1921,9 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg, >> err = total_written; >> } >> out: >> + if (sk->sk_type == SOCK_STREAM) >> + err = sk_stream_error(sk, msg->msg_flags, err); > > Do you know why we don't need this for SOCK_SEQPACKET and SOCK_DGRAM? Yes, here is my explanation: This function checks that input error is SIGPIPE, and if so it sends SIGPIPE to the 'current' thread (except case when MSG_NOSIGNAL flag is set). This behaviour is described in POSIX: Page 367 (description of defines from sys/socket.h): MSG_NOSIGNAL: No SIGPIPE generated when an attempt to send is made on a stream- oriented socket that is no longer connected. Page 497 (description of SOCK_STREAM): A SIGPIPE signal is raised if a thread sends on a broken stream (one that is no longer connected). Page 1802 (description of 'send()' call): MSG_NOSIGNAL Requests not to send the SIGPIPE signal if an attempt to send is made on a stream-oriented socket that is no longer connected. The [EPIPE] error shall still be returned And the same for 'sendto()' and 'sendmsg()' Link to the POSIX document: https://www.open-std.org/jtc1/sc22/open/n4217.pdf TCP (I think we must rely on it), KCM, SMC sockets (all of them are stream) work in the same way by calling this function. AF_UNIX also works in the same way, but it implements SIGPIPE handling without this function. The only thing that confused me a little bit, that sockets above returns EPIPE when we have only SEND_SHUTDOWN set, but for AF_VSOCK EPIPE is returned for RCV_SHUTDOWN also, but I think it is related to this patchset. Thanks, Arseniy > > Thanks, > Stefano > >> + >> release_sock(sk); >> return err; >> } >> -- >> 2.25.1 >> >
