Bug 91072

Summary:	XWayland:connection fails with "maximum number of clients reached"
Product:	xorg	Reporter:	Olivier Fourdan <fourdan>
Component:	Server/General	Assignee:	Xorg Project Team <xorg-team>
Status:	RESOLVED FIXED	QA Contact:	Xorg Project Team <xorg-team>
Severity:	normal
Priority:	medium
Version:	git
Hardware:	Other
OS:	All
See Also:	https://bugzilla.redhat.com/show_bug.cgi?id=1231475
Whiteboard:
i915 platform:		i915 features:

Description Olivier Fourdan 2015-06-23 11:58:00 UTC

The X server code is assuming that one file descriptor is opened per client in os/connection.c , so it limits the number of file descriptors to the number of clients.

Unfortunately Xwayland opens a lot more file descriptors than a regular X server because of those "weston-shared-XXXXXX" anonymous files for sharing buffers.

The number of /extra/ file descriptors opened depends on the client so the actual limit depends on what application is running.

Once the X server (Xwayland) reaches the number of file descriptors opened, it will raise a "Maximum number of clients reached" even if the actual number of clients is a lot less that the expected limit.

Comment 1 Olivier Fourdan 2015-06-23 12:07:57 UTC

Follow-up patch send to the ML for further review/discussion:

http://lists.x.org/archives/xorg-devel/2015-June/046695.html

Comment 2 Chris Wilson 2015-06-23 12:20:13 UTC

Try

diff --git a/hw/xwayland/xwayland-shm.c b/hw/xwayland/xwayland-shm.c
index 2d0ce3e..1022c0d 100644
--- a/hw/xwayland/xwayland-shm.c
+++ b/hw/xwayland/xwayland-shm.c
@@ -82,7 +82,7 @@ create_tmpfile_cloexec(char *tmpname)
     }
 #endif
 
-    return fd;
+    return os_move_fd(fd);
 }
 
 /*

as a shor term fix.

Comment 3 Olivier Fourdan 2015-06-23 13:04:16 UTC

(In reply to Chris Wilson from comment #2)
> Try
> [...]
> -    return fd;
> +    return os_move_fd(fd);

Or right, that's much better, thanks!

> as a shor term fix.

Why just a short term fix? it looks perfectly spot on to me...

Comment 4 Olivier Fourdan 2015-06-23 14:11:35 UTC

BTW, do you mind if I resend a patch as a follow-up to the ML with your solution with you as author and your signed-off-by?

Comment 5 Chris Wilson 2015-06-23 14:20:50 UTC

(In reply to Olivier Fourdan from comment #3)
> (In reply to Chris Wilson from comment #2)
> > Try
> > [...]
> > -    return fd;
> > +    return os_move_fd(fd);
> 
> Or right, that's much better, thanks!
> 
> > as a shor term fix.
> 
> Why just a short term fix? it looks perfectly spot on to me...

I thought you had scenarios requiring more than 256 clients. Certainly seems conceivable that we will run out.

If that works for you send it on with

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

and your Reported-and-tested-by.

Comment 6 Olivier Fourdan 2015-06-23 14:33:36 UTC

(In reply to Chris Wilson from comment #5)
> If that works for you send it on with
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> 
> and your Reported-and-tested-by.

Done here: http://lists.x.org/archives/xorg-devel/2015-June/046722.html

Thanks!

Comment 7 Olivier Fourdan 2015-07-09 11:31:47 UTC

Fix has been merged in git by Keith, closing.

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