linux-kernel - Re: broken pcmcia_bus

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Message-ID: <20100116120410.GB20984@comet.dominikbrodowski.net>
Date:	Sat, 16 Jan 2010 13:04:10 +0100
From:	Dominik Brodowski <linux@...inikbrodowski.net>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	linux-pcmcia@...ts.infradead.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: broken pcmcia_bus_match for dynids

Hey,

On Wed, Jan 13, 2010 at 01:42:05PM +0100, Jiri Slaby wrote:
> stanse found that when PCMCIA_DEV_ID_MATCH_FAKE_CIS is set in
> match_flags for a dynid, the pcmcia layer may deadlock.
> 
> pcmcia_load_firmware in such case calls non-atomic operations
> (request_firmware, kzalloc(GFP_KERNEL)), while dynids.lock spinlock is held.
> 
> Any ideas how to solve this? Any idea, why p_drv->dynids.lock is not a
> mutex instead?

Well, as dynid->id.cisfile is never set, it is still NULL, which means
pcmcia_load_firmware is left immediately, without calling the (blocking)
request_firmare(). So this actually isn't a problem, AFAICS.

Nonetheless, I'll prepare a patch to replace it with a mutex for 2.6.34.

Best,
	Dominik
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