X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fstdio%2F__lockfile.c;h=0f60a14990943605b12038178c595c7210cc0f73;hb=8d404733e1314ef633aa09a90865e94fe711b4ca;hp=9d967d6eb8860c0522b9fcd8505d6e52fad19b6b;hpb=f1c1a5ea8295a3f8e9ea2db8961c5a68e1a3f9ed;p=musl

diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c
index 9d967d6e..0f60a149 100644
--- a/src/stdio/__lockfile.c
+++ b/src/stdio/__lockfile.c
@@ -3,26 +3,21 @@
 
 int __lockfile(FILE *f)
 {
-	int owner, tid = __pthread_self()->tid;
-	if (f->lock == tid)
+	int owner = f->lock, tid = __pthread_self()->tid;
+	if ((owner & ~MAYBE_WAITERS) == tid)
 		return 0;
-	while ((owner = a_cas(&f->lock, 0, tid)))
-		__wait(&f->lock, &f->waiters, owner, 1);
+	owner = a_cas(&f->lock, 0, tid);
+	if (!owner) return 1;
+	while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) {
+		if ((owner & MAYBE_WAITERS) ||
+		    a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner)
+			__futexwait(&f->lock, owner|MAYBE_WAITERS, 1);
+	}
 	return 1;
 }
 
 void __unlockfile(FILE *f)
 {
-	a_store(&f->lock, 0);
-
-	/* The following read is technically invalid under situations
-	 * of self-synchronized destruction. Another thread may have
-	 * called fclose as soon as the above store has completed.
-	 * Nonetheless, since FILE objects always live in memory
-	 * obtained by malloc from the heap, it's safe to assume
-	 * the dereferences below will not fault. In the worst case,
-	 * a spurious syscall will be made. If the implementation of
-	 * malloc changes, this assumption needs revisiting. */
-
-	if (f->waiters) __wake(&f->lock, 1, 1);
+	if (a_swap(&f->lock, 0) & MAYBE_WAITERS)
+		__wake(&f->lock, 1, 1);
 }