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    Subject[PATCH 092/145] printk: Fix rq->lock vs logbuf_lock unlock lock inversion
    Date
    3.8.13.5 -stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: "Bu, Yitian" <ybu@qti.qualcomm.com>

    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
    console_sem.

    Signed-off-by: ybu <ybu@qti.qualcomm.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/E807E903FE6CBE4D95E420FBFCC273B827413C@nasanexd01h.na.qualcomm.com
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    kernel/printk.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/kernel/printk.c b/kernel/printk.c
    index 0f0ac58..37425c3 100644
    --- a/kernel/printk.c
    +++ b/kernel/printk.c
    @@ -1367,9 +1367,9 @@ static int console_trylock_for_printk(unsigned int cpu)
    }
    }
    logbuf_cpu = UINT_MAX;
    + raw_spin_unlock(&logbuf_lock);
    if (wake)
    up(&console_sem);
    - raw_spin_unlock(&logbuf_lock);
    return retval;
    }

    --
    1.8.1.2


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