| Summary: | intel driver hangs in waitpid() for backlight helper process on output hotplug | ||
|---|---|---|---|
| Product: | xorg | Reporter: | Olivier Fourdan <fourdan> |
| Component: | Driver/intel | Assignee: | Chris Wilson <chris> |
| Status: | RESOLVED FIXED | QA Contact: | Intel GFX Bugs mailing list <intel-gfx-bugs> |
| Severity: | normal | ||
| Priority: | medium | ||
| Version: | unspecified | ||
| Hardware: | Other | ||
| OS: | All | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
Ok, I had momentary doubts thinking this meant that your panel's output was being destroyed and was worried. However, we unconditionally call backlight_close() expecting it only to take action if a backlight is attached. commit e7016d30f3a0ae817c77ccbd962f776ac3e7e100 Author: Olivier Fourdan <ofourdan@redhat.com> Date: Wed Apr 29 10:33:19 2015 +0100 backlight: Do not hang forever if helper pid is -1 Backlight helper PID is set to -1 by default, if for some reason it's not set, we may end up with waitpid(-1, ...) which will hang forever. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90230 Signed-off-by: Olivier Fourdan <ofourdan@redhat.com> |
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.
Using Fedora 22, when undocking/docking my laptop with an external monitor attached to the docking station, Xorg will hang on waitpid() for the backlight helper process. Backtrace shows that the PID is -1: #0 0x00007feccda90f3b in __GI___waitpid (pid=-1, stat_loc=stat_loc@entry=0x0, options=options@entry=0) at ../sysdeps/unix/sysv/linux/waitpid.c:40 #1 0x00007fecc8601e58 in backlight_close (b=b@entry=0x97c8c8) at backlight.c:522 #2 0x00007fecc864b85a in sna_output_destroy (output=output@entry=0x97c960) at sna_display.c:3202 #3 0x00007fecc864f1e4 in sna_output_add (sna=sna@entry=0x7feccfeed000, id=<optimized out>, serial=serial@entry=5) at sna_display.c:3944 #4 0x00007fecc8651f21 in sna_mode_discover (sna=sna@entry=0x7feccfeed000) at sna_display.c:4211 #5 0x00007fecc8658198 in sna_handle_uevents (fd=<optimized out>, closure=0x7feccfeed000) at sna_driver.c:771 #6 0x00000000004799e7 in xf86Wakeup (blockData=<optimized out>, err=<optimized out>, pReadmask=0x836360 <LastSelectMask>) at xf86Events.c:284 #7 0x000000000043ee0d in WakeupHandler (result=result@entry=2, pReadmask=pReadmask@entry=0x836360 <LastSelectMask>) at dixutils.c:423 #8 0x0000000000592dc7 in WaitForSomething (pClientsReady=pClientsReady@entry=0x14189c0) at WaitFor.c:229 #9 0x0000000000439fd1 in Dispatch () at dispatch.c:361 #10 0x000000000043e2fb in dix_main (argc=15, argv=0x7ffd512ec9a8, envp=<optimized out>) at main.c:298 #11 0x00007feccd9e9790 in __libc_start_main (main=0x4286f0 <main>, argc=15, argv=0x7ffd512ec9a8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd512ec998) at libc-start.c:289 #12 0x0000000000428729 in _start () It could be a Fedora 22 issue with SElinux (I dont know) but I think it would be safer to check for (b->pid > 0) instead of just ->pid) in backlight_close so that if the PID is not initialized somehow (default value is -1), it won hang. Will send a patch to the ML in a minute for further review/discussion...