>From 5cf1a5c682c8bb0add9adfb5167a63f269136523 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 21 Jul 2014 12:39:56 -0300 Subject: [PATCH 2/2] net: Don't save mid batch datagram processing error for next recvmmsg call MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When the call to the underlying per protocol recvmsg fails for some reason and we already have successfully processed at least one datagram in the batch, we were saving the error for the next recvmmsg (or recvmsg) call, so the user would eventually get notified of what happened. This was found to be fraught with problems, as, for instance, errors could be notified for a different thread than a faulty one providing invalid buffers. So just return the number of datagrams successfully received. Reported-by: David Laight Cc: Caitlin Bestler Cc: Chris Friesen Cc: David Laight Cc: Elie De Brauwer Cc: Michael Kerrisk Cc: Neil Horman Cc: Ondřej Bílka Cc: Paul Moore Cc: Rémi Denis-Courmont Cc: Steven Whitehouse Link: http://lkml.kernel.org/n/net-next-yfgcm0gwo7un6eqf89xw47lo@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- net/socket.c | 29 +++++++---------------------- 1 file changed, 7 insertions(+), 22 deletions(-) diff --git a/net/socket.c b/net/socket.c index 310a50971769..b6836c5fd201 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2436,28 +2436,13 @@ out_put: timeout->tv_nsec = (timeout_hz % HZ) * (NSEC_PER_SEC / HZ); } - if (err == 0) - return datagrams; - - if (datagrams != 0) { - /* - * We may return less entries than requested (vlen) if the - * sock is non block and there aren't enough datagrams... - */ - if (err != -EAGAIN) { - /* - * ... or if recvmsg returns an error after we - * received some datagrams, where we record the - * error to return on the next call or if the - * app asks about it using getsockopt(SO_ERROR). - */ - sock->sk->sk_err = -err; - } - - return datagrams; - } - - return err; + /* + * We may return less entries than requested (vlen) if the + * sock is non block and there aren't enough datagrams or + * if some problem happened after successfully receiving one + * datagram. + */ + return datagrams ?: err; } SYSCALL_DEFINE5(recvmmsg, int, fd, struct mmsghdr __user *, mmsg, -- 1.9.3