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    Subject[PATCH 3.4 004/134] printk: Fix rq->lock vs logbuf_lock unlock lock inversion
    Date
    3.4-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>
    [bwh: Backported to 3.2: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    Cc: Qiang Huang <h.huangqiang@huawei.com>
    Cc: Li Zefan <lizefan@huawei.com>
    Cc: Jianguo Wu <wujianguo@huawei.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/printk.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/kernel/printk.c
    +++ b/kernel/printk.c
    @@ -822,9 +822,9 @@ static int console_trylock_for_printk(un
    }
    }
    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 [] =



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