linux-kernel - Re: use of preempt_count instead of in

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Message-ID: <47E37F86.2080804@s5r6.in-berlin.de>
Date:	Fri, 21 Mar 2008 10:27:34 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Henrique de Moraes Holschuh <hmh@....eng.br>,
	David Brownell <david-b@...bell.net>,
	Richard Purdie <rpurdie@...ys.net>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	netdev@...r.kernel.org,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	linux-usb@...r.kernel.org, linux-wireless@...r.kernel.org,
	video4linux-list@...hat.com, lm-sensors@...sensors.org
Subject: Re: use of preempt_count instead of in_atomic() at leds-gpio.c

I wrote:
> Andrew Morton wrote:
>> ./drivers/ieee1394/ieee1394_transactions.c
>>
>>   Possibly buggy: deadlockable
> 
> That's in hpsb_get_tlabel(), an exported symbol of the ieee1394 core.
> 
> The in_atomic() there didn't cause problems yet and is unlikely to do so 
> in the future, because there are no plans for substantial changes to the 
> whole drivers/ieee1394/ anymore (because of drivers/firewire/).
> 
> Nevertheless I shall look into replacing the in_atomic() by in_softirq() 
> or something like that.

Or extend the API to have separate calls for callers which can sleep and 
callers which can't.  But that may be thwarted by deep call chains.

> Touching this legacy code is dangerous though.
-- 
Stefan Richter
-=====-==--- --== =-=-=
http://arcgraph.de/sr/
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