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authorRich Felker <dalias@aerifal.cx>2011-09-28 19:45:37 -0400
committerRich Felker <dalias@aerifal.cx>2011-09-28 19:45:37 -0400
commitde543b05c87d79a9313991810e9ee8ecdaad8f19 (patch)
treeabde9355e67731c9e8b48ccdd107405cb35b6e03
parentede5ae7b0bb5a7ed9edeb2eeb8e24d30af64d185 (diff)
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fix excessive/insufficient wakes in __vm_unlock
there is no need to send a wake when the lock count does not hit zero, but when it does, all waiters must be woken (since all with the same sign are eligible to obtain the lock).
-rw-r--r--src/thread/pthread_barrier_wait.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/src/thread/pthread_barrier_wait.c b/src/thread/pthread_barrier_wait.c
index 71f7b5fe..6052925a 100644
--- a/src/thread/pthread_barrier_wait.c
+++ b/src/thread/pthread_barrier_wait.c
@@ -13,9 +13,9 @@ void __vm_lock(int inc)
void __vm_unlock(void)
{
- if (vmlock[0]>0) a_dec(vmlock);
- else a_inc(vmlock);
- if (vmlock[1]) __wake(vmlock, 1, 1);
+ int inc = vmlock[0]>0 ? -1 : 1;
+ if (a_fetch_add(vmlock, inc)==-inc && vmlock[1])
+ __wake(vmlock, -1, 1);
}
static int pshared_barrier_wait(pthread_barrier_t *b)