This is a note to let you know that I've just added the patch titled
net: sendmmsg should only return an error if no messages were sent
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sendmmsg-should-only-return-an-error-if-no-messages-were-sent.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@kernel.org> know about it.
>From 728ffb86f10873aaf4abd26dde691ee40ae731fe Mon Sep 17 00:00:00 2001
From: Anton Blanchard <an...@samba.org>
Date: Thu, 4 Aug 2011 14:07:38 +0000
Subject: net: sendmmsg should only return an error if no messages were sent
From: Anton Blanchard <an...@samba.org>
commit 728ffb86f10873aaf4abd26dde691ee40ae731fe upstream.
sendmmsg uses a similar error return strategy as recvmmsg but it
turns out to be a confusing way to communicate errors.
The current code stores the error code away and returns it on the next
sendmmsg call. This means a call with completely valid arguments could
get an error from a previous call.
Change things so we only return an error if no datagrams could be sent.
If less than the requested number of messages were sent, the application
must retry starting at the first failed one and if the problem is
persistent the error will be returned.
This matches the behaviour of other syscalls like read/write - it
is not an error if less than the requested number of elements are sent.
Signed-off-by: Anton Blanchard <an...@samba.org>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@suse.de>
---
net/socket.c | 27 +++------------------------
1 file changed, 3 insertions(+), 24 deletions(-)
--- a/net/socket.c
+++ b/net/socket.c
@@ -2005,12 +2005,9 @@ int __sys_sendmmsg(int fd, struct mmsghd
if (!sock)
return err;
- err = sock_error(sock->sk);
- if (err)
- goto out_put;
-
entry = mmsg;
compat_entry = (struct compat_mmsghdr __user *)mmsg;
+ err = 0;
while (datagrams < vlen) {
/*
@@ -2037,29 +2034,11 @@ int __sys_sendmmsg(int fd, struct mmsghd
++datagrams;
}
-out_put:
fput_light(sock->file, fput_needed);
- if (err == 0)
- return datagrams;
-
- if (datagrams != 0) {
- /*
- * We may send less entries than requested (vlen) if the
- * sock is non blocking...
- */
- if (err != -EAGAIN) {
- /*
- * ... or if sendmsg returns an error after we
- * send 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;
- }
-
+ /* We only return an error if no datagrams were able to be sent */
+ if (datagrams != 0)
return datagrams;
- }
return err;
}
Patches currently in stable-queue which might be from an...@samba.org are
queue-3.0/net-cap-number-of-elements-for-sendmmsg.patch
queue-3.0/net-fix-security_socket_sendmsg-bypass-problem.patch
queue-3.0/net-sendmmsg-should-only-return-an-error-if-no-messages-were-sent.patch
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