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winpr/synch: fix barrier deadlock in release build 

Let the compiler know that we're comparing a volatile value.
Otherwise the compiler might nuke the comparison operation
and produce code that will spin endlessly.
This commit is contained in:
Norbert Federa 2016-06-07 13:06:50 +02:00
parent aa15327a3a
commit f969e60a53
1 changed files with 6 additions and 1 deletions
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7
winpr/libwinpr/synch/barrier.c
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@ -193,8 +193,13 @@ BOOL WINAPI EnterSynchronizationBarrier(LPSYNCHRONIZATION_BARRIER lpBarrier, DWO
{
DWORD dwSpinCount = lpBarrier->Reserved5;
DWORD sp = 0;
/**
* nb: we must let the compiler know that our comparand
* can change between the iterations in the loop below
*/
volatile ULONG_PTR* cmp = &lpBarrier->Reserved3[0];
/* we spin until the last thread _completed_ the event switch */
while ((block = (lpBarrier->Reserved3[0] == (ULONG_PTR)hCurrentEvent)))
while ((block = (*cmp == (ULONG_PTR)hCurrentEvent)))
if (!spinOnly && ++sp > dwSpinCount)
break;
}