use atomic decrement rather than cas in pthread_exit thread count

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 6a37ee9..0567f96 100644 (file)
--- 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