From: Petr Mladek <pmladek@suse.com>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: daniel.thompson@linaro.org, kgdb-bugreport@lists.sourceforge.net,
jason.wessel@windriver.com, dianders@chromium.org,
sergey.senozhatsky@gmail.com, gregkh@linuxfoundation.org,
jslaby@suse.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/4] kdb: Make kdb_printf() console handling more robust
Date: Wed, 3 Jun 2020 10:10:26 +0200 [thread overview]
Message-ID: <20200603081025.GC14855@linux-b0ei> (raw)
In-Reply-To: <1591168935-6382-4-git-send-email-sumit.garg@linaro.org>
On Wed 2020-06-03 12:52:14, Sumit Garg wrote:
> While rounding up CPUs via NMIs, its possible that a rounded up CPU
> maybe holding a console port lock leading to kgdb master CPU stuck in
> a deadlock during invocation of console write operations. A similar
> deadlock could also be possible while using synchronous breakpoints.
>
> So in order to avoid such a deadlock, set oops_in_progress to encourage
> the console drivers to disregard their internal spin locks: in the
> current calling context the risk of deadlock is a bigger problem than
> risks due to re-entering the console driver. We operate directly on
> oops_in_progress rather than using bust_spinlocks() because the calls
> bust_spinlocks() makes on exit are not appropriate for this calling
> context.
>
> Suggested-by: Petr Mladek <pmladek@suse.com>
I think that this was actually suggested by Sergey.
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> Reviewed-by: Douglas Anderson <dianders@chromium.org>
Otherwise, it looks good. With updated suggested by:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards,
Petr
next prev parent reply other threads:[~2020-06-03 8:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-03 7:22 [PATCH v5 0/4] kdb: Improve console handling Sumit Garg
2020-06-03 7:22 ` [PATCH v5 1/4] kdb: Re-factor kdb_printf() message write code Sumit Garg
2020-06-03 8:07 ` Petr Mladek
2020-06-03 7:22 ` [PATCH v5 2/4] kdb: Check status of console prior to invoking handlers Sumit Garg
2020-06-03 8:08 ` Petr Mladek
2020-06-03 7:22 ` [PATCH v5 3/4] kdb: Make kdb_printf() console handling more robust Sumit Garg
2020-06-03 8:10 ` Petr Mladek [this message]
2020-06-03 7:22 ` [PATCH v5 4/4] kdb: Switch to use safer dbg_io_ops over console APIs Sumit Garg
2020-06-03 8:25 ` Petr Mladek
2020-06-03 9:18 ` Daniel Thompson
2020-06-03 11:59 ` Petr Mladek
2020-06-03 9:32 ` Sumit Garg
2020-06-03 11:42 ` Daniel Thompson
2020-06-03 13:05 ` Sumit Garg
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