Wayland/weston opens files in suspend/resume

[Pekka Paalanen]

On Wed, 22 Aug 2018 12:18:00 +0300
Teemu K <maillinglists18 at gmail.com> wrote:

> Hi,
> 
> I have custom iMX6 based HW running image generated with Yocto 2.4
> (Wayland 2.0.0) and Linux kernel 4.1.x that I've been testing with
> suspend/resume cycles.
> 
> I noticed that after each suspend/resume cycle open file count
> increases. In my testing I got around 490 suspend/resume cycles until
> libwayland gave error that there is too many open files.
> --
> [14:29:52.385] libwayland: dup failed: Too many open files
> [14:29:52.385] caught signal: 6
> The Wayland connection broke. Did the Wayland compositor die?
> --
> Looking at the lsof output after around 60 suspend/resume cycles I can
> see that for example this file appears 60 more times:
> --
> weston      921            root   11u      CHR       29,0      0t0
> 5323 /dev/fb0
> --
> 
> The 11u part changes, but other parts are same. First time there is
> 11u and 13u but later it goes all the way to 93u (some numbers are
> missing).
> 
> Also my QT application running when suspending keeps keeping these
> kinds of files open which I assume (I may be wrong) because the
> weston.
> 
> --
> qtapplicat   929  965       root   11u      REG       0,18    48097
> 12272 /run/user/root/weston-shared-24Zz9a (deleted)
> --
> 
> I know that the Weston is quite old since I think 4.0.0 has already
> come out,but is there any known bug that causes this? I did a search,
> but couldn't find any. I know it's rare to need suspend/resume over
> 400 times without cutting power at some point, but I'm sure there'll
> be that one customer that does it.

Hi,

I hope it would be more correct to say it's rare to see anyone care
about the fbdev backend. ;-)

Leaking file descriptors to /dev/fb0 over suspend/resume does not
surprise me, but I don't recall any bug reports or fixes exactly to that
effect. Also the fbdev device handling has been changed since Weston
2.0.0, so it's possible it might be already fixed. Or maybe not. I seem
to recall that VT switching with the fbdev-backend has been broken for
years.

I would not expect Weston to ever have made a dozen open file
descriptors to /dev/fb0. Are you sure you are not using proprietary EGL
drivers with the fbdev-backend? If you use EGL with fbdev, then we
certainly cannot help you.

If you found fd leaking with the DRM-backend and a more recent release,
there would be much more interest in it. However, I suppose we do still
take patches to fix bugs in the fbdev-backend for master branch, even
though we probably reject any feature additions (complicated ones at
least).

weston-shared-* file might be a keymap, nothing else comes to mind that
Weston would allocate, and I hope Qt does not use weston's name for its
own stuff.


Thanks,
pq
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