reds: increase listening socket backlog

With a TCP socket, the backlog doesn't seem to matter much,
perhaps because of latency or underlying protocol behaviour. However,
on UNIX socket, it is fairly easy to reach the backlog limit and the
client will get an EAGAIN error (but not ECONNREFUSED as stated in
listen(7)) that is not easy to deal with: attempting to reconnect in a
loop might busy-loop forever as there are no guarantee the server will
accept new connections, so it will be inherently racy.

Typically, Spice server can easily have up to 15 concurrent incoming
connections that are established during initialization of the session.
To improve the situation, raise the backlog limit to the default maximum
system value, which is 128 on Linux.

1 files changed, 1 insertions, 1 deletions

diff --git a/server/reds.c b/server/reds.c
index cc26ca7e..56e87a22 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -2452,7 +2452,7 @@ static int reds_init_socket(const char *addr, int portnr, int family)
     return -1;
 
 listen:
-    if (listen(slisten,1) != 0) {
+    if (listen(slisten, SOMAXCONN) != 0) {
         spice_warning("listen: %s", strerror(errno));
         close(slisten);
         return -1;