[mythtv-commits] Ticket #4206: frontend segfault when switching resolutions for playback

[MythTV]

#4206: frontend segfault when switching resolutions for playback
---------------------------------------------+------------------------------
 Reporter:  George Nassas <gnassas at mac.com>  |        Owner:  ijr    
     Type:  defect                           |       Status:  new    
 Priority:  minor                            |    Milestone:  unknown
Component:  mythtv                           |      Version:  head   
 Severity:  medium                           |   Resolution:         
  Mlocked:  0                                |  
---------------------------------------------+------------------------------

Comment(by George Nassas <gnassas at mac.com>):

 This ticket can be closed, I've traced it to a mesa bug and I'll persue it
 further over there.

 For anyone keeping score at home various myth threads open and close the
 display for local queries. Inside X11 this eventually works its way down
 to dri_glx.c::OpenDriver which dlopen's the correct .so on the first call.
 Subsequent calls get the handle from that initial dlopen.

 Unfortunately this doesn't increment the reference count for the .so and a
 dlclose at the first nested XOpenDisplay/XCloseDisplay (like in
 libmythtv's get_glx_version) causes the dri library to be unloaded and
 soon after that MythTV go boom. The unload message in the initial report
 turned out to be the key, something I realized moments after submitting
 the bug.

 The quick fix, and this is Linux-specific, is to tweak the inital search
 at the top of OpenDriver in mesa's dri_glx.c. The match should change
 from:

 {{{
       if (strcmp(driver->name, driverName) == 0) {
          /* found it */
          return driver;
       }
 }}}

 to

 {{{
       if (strcmp(driver->name, driverName) == 0) {
          /* found it */
          char *libPath = ((struct link_map *)(driver->handle))->l_name;
          dlopen(libPath, RTLD_NOW | RTLD_GLOBAL);
          return driver;
       }
 }}}

 make sure you #include <link.h> at the top.

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/4206#comment:1>
MythTV <http://svn.mythtv.org/trac>
MythTV