[Bug libgomp/50175] data race with OMP barrier

[Joost.VandeVondele at mat dot ethz.ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50175



Joost VandeVondele Joost.VandeVondele at mat dot ethz.ch changed:



   What|Removed |Added



 Status|UNCONFIRMED |RESOLVED

 CC||Joost.VandeVondele at mat

   ||dot ethz.ch

 Resolution||DUPLICATE



--- Comment #2 from Joost VandeVondele Joost.VandeVondele at mat dot ethz.ch 
2013-03-29 09:11:10 UTC ---

This is at best a dup of PR40362, and likely fixed for the linux futex version

as 

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55561#c38



*** This bug has been marked as a duplicate of bug 40362 ***

[Bug libgomp/50175] data race with OMP barrier

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50175

Jakub Jelinek jakub at gcc dot gnu.org changed:

   What|Removed |Added

 CC||jakub at gcc dot gnu.org,
   ||rth at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek jakub at gcc dot gnu.org 2011-08-24 
14:55:18 UTC ---
If this is about bar-arrived writes, then I don't see any races.
During the lifetime of a barrier, in the first phase arrived is incremented by
each thread, guarded by bar-mutex1 lock.  The threads then unlock bar-mutex1
lock, except for the last thread which keeps it locked and decrements
bar-arrived again, then, still with bar-mutex1 locked wakes up all the other
threads which then either atomically, or guarded with bar-mutex2 lock,
decrement bar-arrived again.  The last of those threads then posts to
bar-sem2
semaphore on which the thread holding bar-mutex1 is waiting before unlocking
that lock.  Thus, I don't see how the first phase (where bar-arrived
adjustments are done guarded with bar-mutex1 lock) can overlap with the second
phase (where it is decremented atomically or with mutex2).  Not even the second
phase with following first phase.  Thus I think valgrind is wrong about this.

CCing rth as author...