Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.4 004/134] printk: Fix rq->lock vs logbuf_lock unlock lock inversion | Date | Wed, 9 Apr 2014 20:22:00 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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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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