Attachment 123464 Details for Bug 95264 – the patch

[patch] the patch

0001-sysdeps-increase-listen-backlog-of-AF_UNIX-sockets-t.patch (text/plain), 1.81 KB, created by Lennart Poettering on 2016-05-04 16:15:37 UTC

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Creator: Lennart Poettering

Created: 2016-05-04 16:15:37 UTC

Size: 1.81 KB

patch

obsolete

>From f20e80ab91d298b9e670171cdac8e25ea612eca2 Mon Sep 17 00:00:00 2001
>From: Lennart Poettering <lennart@poettering.net>
>Date: Wed, 4 May 2016 18:06:17 +0200
>Subject: [PATCH] sysdeps: increase listen() backlog of AF_UNIX sockets to
> SOMAXCONN
>
>Previously, the listen() backlog was set to an arbitrary 30. This means
>that if dbus-daemon is overloaded only 30 more connections may be queued
>by the kernel, before connect() fails with EAGAIN. (Note that EAGAIN !=
>EINPROGRESS -- the latter is what is returned if a connection is queued
>and being processed for asynchronous sockets; EAGAIN in this case is
>really an error, that cannot be recovered from).
>
>Most software simply sets SOMAXCONN as backlog for AF_UNIX sockets, to
>allow queuing of as many connections as the kernel allows. SOMAXCONN is
>128 on Linux, which is not particularly high, but at least higher than
>30.
>
>This patch changes dbus-daemon to do the same.
>
>I noticed this when flooding dbus-daemon with a lot of connections,
>where it pretty quickly ceased to respond, much earlier than it really
>should.
>
>Note that the backlog has nothing to do with the number of concurrent
>connections allowed, it simply controls how many queued, but not
>accept()ed connections there may be on the listening socket.
>---
> dbus/dbus-sysdeps-unix.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
>index 6b9e50b..ce8cbf7 100644
>--- a/dbus/dbus-sysdeps-unix.c
>+++ b/dbus/dbus-sysdeps-unix.c
>@@ -1120,7 +1120,7 @@ _dbus_listen_unix_socket (const char     *path,
>       return -1;
>     }
> 
>-  if (listen (listen_fd, 30 /* backlog */) < 0)
>+  if (listen (listen_fd, SOMAXCONN /* backlog */) < 0)
>     {
>       dbus_set_error (error, _dbus_error_from_errno (errno),
>                       "Failed to listen on socket \"%s\": %s",
>-- 
>2.7.4
>

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