[JFFS2] Fix lack of locking in thread_should_wake()

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=b27cf88e9592953ae292d05324887f2f44979433
Commit:     b27cf88e9592953ae292d05324887f2f44979433
Parent:     f04de505e3fa322728d1a851e08bf7060b117743
Author:     David Woodhouse <David.Woodhouse at intel.com>
AuthorDate: Fri Oct 31 14:52:24 2008 +0000
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Fri Oct 31 14:52:24 2008 +0000

    [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 at intel.com>
    Cc: stable at kernel.org
---
 fs/jffs2/background.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

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 @@ 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