[GHC] #7303: RTS : Race condition with usage of timer_delete

[GHC]

#7303: RTS : Race condition with usage of timer_delete
---------------------------------+------------------------------------------
 Reporter:  erikd                |          Owner:                  
     Type:  bug                  |         Status:  new             
 Priority:  normal               |      Component:  Compiler        
  Version:  7.7                  |       Keywords:                  
       Os:  Linux                |   Architecture:  Unknown/Multiple
  Failure:  Building GHC failed  |       Testcase:                  
Blockedby:                       |       Blocking:                  
  Related:                       |  
---------------------------------+------------------------------------------
 Using Qemu (CPU emulator) to build GHC for Arm, the build ocassionally
 dies with either a segfault just before exit or hangs just before exit (ie
 the output files are written and seem complete, but GHC does not terminate
 cleanly causing the build to halt).

 While debugging POSIX timer support in Qemu I wrote a little test program
 for POSIX timers and found that under Qemu, about 1 time in 10, the signal
 related to the POSIX timer gets delivered *after* the timer is deleted and
 causes either a segfault or a hang. While I have only seen this happen for
 sure with Qemu/ARM emulation, the asynchronous nature of signals suggests
 that this is theoretically possible in real (ie non-emulated) systems.

 Already have a tested patch to fix this.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7303>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler