[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

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c
index 8adebd3e43c6..3cceef4ad2b7 100644
--- a/fs/jffs2/background.c
+++ b/fs/jffs2/background.c
@@ -85,15 +85,15 @@ static int jffs2_garbage_collect_thread(void *_c)
         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