[GHC] #2858: Segmentation fault due to race between IO manager and installSignals.

[GHC]

#2858: Segmentation fault due to race between IO manager and installSignals.
------------------------------------------------+---------------------------
    Reporter:  dsh                              |        Owner:  igloo  
        Type:  merge                            |       Status:  new    
    Priority:  normal                           |    Milestone:  6.10.2 
   Component:  libraries/base                   |      Version:  6.10.1 
    Severity:  normal                           |   Resolution:         
    Keywords:  posix signal threaded IOmanager  |   Difficulty:  Unknown
    Testcase:                                   |           Os:  Linux  
Architecture:  Unknown/Multiple                 |  
------------------------------------------------+---------------------------
Changes (by simonmar):

  * owner:  simonmar => igloo
  * type:  bug => merge

Comment:

 I think these patches should fix the problem, since we no longer have the
 RTS table of `StablePtrs` to signal handlers.  I'd be grateful if you
 could test the new code and let me know if you still encounter any
 problems.

 patch to libraries/unix:

 {{{
 Thu Feb 19 02:05:32 PST 2009  Simon Marlow <marlowsd at gmail.com>
   * Rewrite of signal-handling.
   Ignore-this: 1579194c10020dc34af715c225a9f207

   The API is the same (for now).  The new implementation has the
   capability to define signal handlers that have access to the siginfo
   of the signal (#592), but this functionality is not exposed in this
   patch.

   #2451 is the ticket for the new API.

   The main purpose of bringing this in now is to fix race conditions in
   the old signal handling code (#2858).  Later we can enable the new
   API in the HEAD.

   Implementation differences:

    - More of the signal-handling is moved into Haskell.  We store the
      table of signal handlers in an MVar, rather than having a table of
      StablePtrs in the RTS.

    - In the threaded RTS, the siginfo of the signal is passed down the
      pipe to the IO manager thread, which manages the business of
      starting up new signal handler threads.  In the non-threaded RTS,
      the siginfo of caught signals is stored in the RTS, and the
      scheduler starts new signal handler threads.
 }}}

 patch to libraries/base:

 {{{
 Thu Feb 19 02:22:03 PST 2009  Simon Marlow <marlowsd at gmail.com>
   * Rewrite of signal-handling (base patch; see also ghc and unix patches)
 }}}

 patch to ghc:

 {{{
 Thu Feb 19 02:31:42 PST 2009  Simon Marlow <marlowsd at gmail.com>
   * Rewrite of signal-handling (ghc patch; see also base and unix patches)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2858#comment:9>
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