dm snapshot: change yield to msleep
Change yield() to msleep(1). If the thread had realtime priority,
yield() doesn't really yield, so the yielding process would loop
indefinitely and cause machine lockup.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 6c96db2..4ceedd4 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -9,6 +9,7 @@
#include <linux/blkdev.h>
#include <linux/ctype.h>
#include <linux/device-mapper.h>
+#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kdev_t.h>
@@ -735,7 +736,7 @@
unregister_snapshot(s);
while (atomic_read(&s->pending_exceptions_count))
- yield();
+ msleep(1);
/*
* Ensure instructions in mempool_destroy aren't reordered
* before atomic_read.
@@ -888,10 +889,10 @@
/*
* Check for conflicting reads. This is extremely improbable,
- * so yield() is sufficient and there is no need for a wait queue.
+ * so msleep(1) is sufficient and there is no need for a wait queue.
*/
while (__chunk_is_tracked(s, pe->e.old_chunk))
- yield();
+ msleep(1);
/*
* Add a proper exception, and remove the