File increase-backlog.patch of Package dbus-1.4018

commit 12bd6e893c91430fdbdf8a27087d4a792b04eef9
Author: Lennart Poettering <lennart@poettering.net>
Date:   Wed May 4 18:06:17 2016 +0200

    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.
    
    https://bugs.freedesktop.org/show_bug.cgi?id=95264

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",