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authorRich Felker <dalias@aerifal.cx>2013-04-26 16:05:39 -0400
committerRich Felker <dalias@aerifal.cx>2013-04-26 16:05:39 -0400
commitc3a6839ce95c0f93bd73f7fbe5fcaee4054e5b62 (patch)
tree266e3a83fb5a0ffc2ed146035c58b17f7a1f280e
parent6e531f999a82cf39a951e1e9bba3cb80a6eb1464 (diff)
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use atomic decrement rather than cas in pthread_exit thread count
now that blocking signals prevents any application code from running
while the last thread is exiting, the cas logic is no longer needed to
prevent decrementing below zero.
-rw-r--r--src/thread/pthread_create.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 6a37ee9b..0567f966 100644
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -12,7 +12,6 @@ weak_alias(dummy_0, __pthread_tsd_run_dtors);
 _Noreturn void pthread_exit(void *result)
 {
 	pthread_t self = pthread_self();
-	int n;
 
 	self->result = result;
 
@@ -38,9 +37,7 @@ _Noreturn void pthread_exit(void *result)
 	 * reasons as well. */
 	__syscall(SYS_rt_sigprocmask, SIG_BLOCK, SIGALL_SET, 0, _NSIG/8);
 
-	do n = libc.threads_minus_1;
-	while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
-	if (!n) exit(0);
+	if (a_fetch_add(&libc.threads_minus_1, -1)==0) exit(0);
 
 	if (self->detached && self->map_base) {
 		/* Detached threads must avoid the kernel clear_child_tid