linux-kernel - [PATCH 0/9] Fix unsafe disable

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Date:	Thu, 16 Apr 2009 15:54:05 +1000
From:	Ben Nizette <bn@...sdigital.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	dan.j.williams@...el.com, Eric Miao <eric.miao@...vell.com>,
	linux@....linux.org.uk, dmitry.torokhov@...il.com,
	p_gortmaker@...oo.com, David Brownell <david-b@...bell.net>,
	sameo@...ux.intel.com, linux-omap@...r.kernel.org,
	pierre@...man.eu, linux-input@...r.kernel.org
Subject: [PATCH 0/9] Fix unsafe disable_irq usage

After being bitten by unsafe usage of disable_irq from within that irq's
handler [1], I went through and used Coccinelle to audit the rest of
drivers/ too.  This turned up 9 more unsafe usages.

As Haavard pointed out in that thread, disable_irq waits for running
handlers of an irq to complete before returning.  When a handler
disable_irq's its own irq then we see a deadlock.

Note that this wasn't actually observed in the wild until the recent
merge of

commit 3aa551c9b4c40018f0e261a178e3d25478dc04a9
Author: Thomas Gleixner <tglx@...utronix.de>
Date:   Mon Mar 23 18:28:15 2009 +0100

    genirq: add threaded interrupt handler support

    Add support for threaded interrupt handlers



Regards,
	--Ben.


[1] http://lkml.org/lkml/2009/4/15/498

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