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@xxxxxxxxxxxxx>
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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