X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fstdio%2F__lockfile.c;h=9d967d6eb8860c0522b9fcd8505d6e52fad19b6b;hp=4e0239e7e96399761effc4f60b8a151887454a07;hb=9cb6e6ea120cfaf1df9016883012d22fb57d43e1;hpb=eb0e8fa0b1960cff4bd65ebefc798f70273b0bc9

diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c
index 4e0239e7..9d967d6e 100644
--- a/src/stdio/__lockfile.c
+++ b/src/stdio/__lockfile.c
@@ -1,20 +1,28 @@
 #include "stdio_impl.h"
 #include "pthread_impl.h"
 
-void __lockfile(FILE *f)
+int __lockfile(FILE *f)
 {
-	int spins=100000;
-	int tid;
+	int owner, tid = __pthread_self()->tid;
+	if (f->lock == tid)
+		return 0;
+	while ((owner = a_cas(&f->lock, 0, tid)))
+		__wait(&f->lock, &f->waiters, owner, 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->lock < 0) return;
-	tid = __pthread_self()->tid;
-	if (f->lock == tid) {
-		while (f->lockcount == INT_MAX);
-		f->lockcount++;
-		return;
-	}
-	while (a_cas(&f->lock, 0, tid))
-		if (spins) spins--, a_spin();
-		else __syscall(SYS_sched_yield);
-	f->lockcount = 1;
+	if (f->waiters) __wake(&f->lock, 1, 1);
 }