git » libfilo » commit a6bd4eb

diff --git a/libfilo.c b/libfilo.c
index 361f7e0..e9c30cd 100644
--- a/libfilo.c
+++ b/libfilo.c
@@ -319,39 +319,45 @@ int filo_trylock(filock_t *fl, off_t start, off_t len, int mode)
 
 static void wait_on(filock_t *fl, off_t start, off_t end, int mode)
 {
-	/* all waiter_ranges live on the heap and are created and destroyed
-	 * here. A wr is born here, go to bed in the locking below, until
-	 * wake_up() wakes us up and he dies. While it is manipulated several
-	 * times outside this function, here is the only place where it's
-	 * actually modified. */
-	struct waiter_range wr;
+	/* all waiter_ranges are created and destroyed here. A wr is born
+	 * here, go to bed in the locking below, until wake_up() wakes us up
+	 * and he dies. While it is manipulated several times outside this
+	 * function, here is the only place where it's actually modified; it
+	 * used to be allocated directly on the stack, but maybe some stuff
+	 * assume thread stack is not touched by other threads and it could
+	 * cause some problems in the future; remember: "better safe than
+	 * sorry". */
+	struct waiter_range *wr;
+	wr = malloc(sizeof(struct waiter_range));
 
 	/* initialize wr */
-	wr.start = start;
-	wr.end = end;
-	wr.mode = mode;
-	wr.owner = pthread_self();
-	wr.next = NULL;
-	wr.prev = NULL;
+	wr->start = start;
+	wr->end = end;
+	wr->mode = mode;
+	wr->owner = pthread_self();
+	wr->next = NULL;
+	wr->prev = NULL;
 
-	sem_init(&(wr.sem), 0, 0);
+	sem_init(&(wr->sem), 0, 0);
 
 	/* add to the semi-circular list */
 	if (fl->waiters == NULL) {
-		wr.next = NULL;
-		wr.prev = ≀
-		fl->waiters = ≀
+		wr->next = NULL;
+		wr->prev = wr;
+		fl->waiters = wr;
 	} else {
-		wr.next = NULL;
-		wr.prev = fl->waiters->prev;
-		fl->waiters->prev->next = ≀
-		fl->waiters->prev = ≀
+		wr->next = NULL;
+		wr->prev = fl->waiters->prev;
+		fl->waiters->prev->next = wr;
+		fl->waiters->prev = wr;
 	}
 
 	fl_unlock(fl);
 
 	/* block until some other thread wakes us up */
-	sem_wait(&(wr.sem));
+	sem_wait(&(wr->sem));
+
+	free(wr);
 }
 
 static void wake_up(filock_t *fl, off_t start, off_t end)
@@ -383,11 +389,8 @@ static void wake_up(filock_t *fl, off_t start, off_t end)
 				wr->next->prev = wr->prev;
 			}
 
-			/* it lives on wait_on()'s stack, there's no need to
-			 * free it */
-
-			/* this will wake the thread up (and the thread will
-			 * destroy wr) */
+			/* this will wake the thread up, which is blocked in
+			 * wait_on(), and it will then free wr */
 			sem_post(&(wr->sem));
 
 			return;