From: "Bu, Yitian" <ybu@xxxxxxxxxxxxxxxx>
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
console_sem.
Signed-off-by: ybu <ybu@xxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Cc: stable-rt@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/E807E903FE6CBE4D95E420FBFCC273B827413C@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/printk.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index 972cc56..37b9b99 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -867,9 +867,9 @@ static int console_trylock_for_printk(unsigned int cpu, unsigned long flags)
}
}
printk_cpu = UINT_MAX;
+ raw_spin_unlock(&logbuf_lock);
if (wake)
up(&console_sem);
- raw_spin_unlock(&logbuf_lock);
return retval;
}
static const char recursion_bug_msg [] =
--
1.7.10.4
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