[02/85] printk: Fix rq->lock vs logbuf_lock unlock lock inversion

From: Ben Hutchings
Date: Wed Jul 24 2013 - 10:32:50 EST

3.2.49-rc1 review patch. If anyone has any objections, please let me know.


From: "Bu, Yitian" <ybu@xxxxxxxxxxxxxxxx>

commit dbda92d16f8655044e082930e4e9d244b87fde77 upstream.

commit 07354eb1a74d1 ("locking printk: Annotate logbuf_lock as raw")
reintroduced a lock inversion problem which was fixed in commit
0b5e1c5255 ("printk: Release console_sem after logbuf_lock"). This
happened probably when fixing up patch rejects.

Restore the ordering and unlock logbuf_lock before releasing

Signed-off-by: ybu <ybu@xxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/E807E903FE6CBE4D95E420FBFCC273B827413C@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
kernel/printk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -813,9 +813,9 @@ static int console_trylock_for_printk(un
printk_cpu = UINT_MAX;
+ raw_spin_unlock(&logbuf_lock);
if (wake)
- raw_spin_unlock(&logbuf_lock);
return retval;
static const char recursion_bug_msg [] =

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