[JFFS2] Fix lack of locking in thread_should_wake()
The thread_should_wake() function trawls through the list of 'very
dirty' eraseblocks, determining whether the background GC thread should
wake. Doing this without holding the appropriate locks is a bad idea.
OLPC Trac #8615
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org
diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
index 8adebd3..3cceef4 100644
--- a/fs/jffs2/background.c
+++ b/fs/jffs2/background.c
@@ -85,15 +85,15 @@
for (;;) {
allow_signal(SIGHUP);
again:
+ spin_lock(&c->erase_completion_lock);
if (!jffs2_thread_should_wake(c)) {
set_current_state (TASK_INTERRUPTIBLE);
+ spin_unlock(&c->erase_completion_lock);
D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
- /* Yes, there's a race here; we checked jffs2_thread_should_wake()
- before setting current->state to TASK_INTERRUPTIBLE. But it doesn't
- matter - We don't care if we miss a wakeup, because the GC thread
- is only an optimisation anyway. */
schedule();
- }
+ } else
+ spin_unlock(&c->erase_completion_lock);
+
/* This thread is purely an optimisation. But if it runs when
other things could be running, it actually makes things a