From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Gu Zheng <guz.fnst@cn.fujitsu.com>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH RESEND] fb: reorder the lock sequence to fix a potential lockdep
Date: Wed, 30 Oct 2013 11:20:37 +0000 [thread overview]
Message-ID: <5270EB85.1030103@ti.com> (raw)
In-Reply-To: <526DFDA8.7010806@cn.fujitsu.com>
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Hi,
On 2013-10-28 08:01, Gu Zheng wrote:
> Following commits:
> 50e244cc79 fb: rework locking to fix lock ordering on takeover
> e93a9a8687 fb: Yet another band-aid for fixing lockdep mess
> 054430e773 fbcon: fix locking harder
>
> reworked locking to fix related lock ordering on takeover, and introduced console_lock
> into fbmem, but it seems that the new lock sequence(fb_info->lock ---> console_lock)
> is against with the one in console_callback(console_lock ---> fb_info->lock), and leads to
> a potential deadlock as following:
A quick grep shows that there are other places than fbmem.c which use
lock_fb_info and console_lock, for example drivers/video/sh_mobile_lcdcfb.c.
Tomi
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WARNING: multiple messages have this Message-ID (diff)
From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Gu Zheng <guz.fnst@cn.fujitsu.com>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH RESEND] fb: reorder the lock sequence to fix a potential lockdep
Date: Wed, 30 Oct 2013 13:20:37 +0200 [thread overview]
Message-ID: <5270EB85.1030103@ti.com> (raw)
In-Reply-To: <526DFDA8.7010806@cn.fujitsu.com>
[-- Attachment #1: Type: text/plain, Size: 714 bytes --]
Hi,
On 2013-10-28 08:01, Gu Zheng wrote:
> Following commits:
> 50e244cc79 fb: rework locking to fix lock ordering on takeover
> e93a9a8687 fb: Yet another band-aid for fixing lockdep mess
> 054430e773 fbcon: fix locking harder
>
> reworked locking to fix related lock ordering on takeover, and introduced console_lock
> into fbmem, but it seems that the new lock sequence(fb_info->lock ---> console_lock)
> is against with the one in console_callback(console_lock ---> fb_info->lock), and leads to
> a potential deadlock as following:
A quick grep shows that there are other places than fbmem.c which use
lock_fb_info and console_lock, for example drivers/video/sh_mobile_lcdcfb.c.
Tomi
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next prev parent reply other threads:[~2013-10-30 11:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-28 6:01 [RFC PATCH RESEND] fb: reorder the lock sequence to fix a potential lockdep Gu Zheng
2013-10-28 6:01 ` Gu Zheng
2013-10-30 3:18 ` Gu Zheng
2013-10-30 3:18 ` Gu Zheng
2013-10-30 11:20 ` Tomi Valkeinen [this message]
2013-10-30 11:20 ` Tomi Valkeinen
2013-10-31 1:17 ` Gu Zheng
2013-10-31 1:17 ` Gu Zheng
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