linux-kernel - [PATCH 0/2] kdb: Fix locking in vkdb

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Date:   Fri, 21 Oct 2016 14:50:33 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Jason Wessel <jason.wessel@...driver.com>
Cc:     Daniel Thompson <daniel.thompson@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: [PATCH 0/2] kdb: Fix locking in vkdb_printf()

I have been asked whether it is safe to call vkdb_printf() from
vprintk_nmi() in NMI context. It seems that it is not safe.
Well, is not a big deal.

But I have noticed suspicious patterns when looking at the
vkdb_printf() locking code and prepared two patches that
should avoid some possible races.

Please, note that I am not familiar with the kdb implementation.
I hope that I have got the requested behavior right. I did
some basic testing and did not found any problem. But I am sure
that I did not test all usecases.

Petr Mladek (2):
  kdb: Properly synchronize vkdb_printf() calls with other CPUs
  kdb: Call vkdb_printf() from vprintk_default() only when wanted

 include/linux/kdb.h            |  1 +
 kernel/debug/kdb/kdb_io.c      | 41 +++++++++++++++++------------------------
 kernel/debug/kdb/kdb_private.h |  1 -
 kernel/printk/printk.c         |  4 +++-
 4 files changed, 21 insertions(+), 26 deletions(-)

-- 
1.8.5.6