Re: [RFC PATCH RESEND] fb: reorder the lock sequence to fix a potentiallockdep

From: Tomi Valkeinen
Date: Wed Oct 30 2013 - 07:20:49 EST


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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