Re: pstore dump inside an nmi handler

[David Miller]

From: "Luck, Tony" <tony.luck@xxxxxxxxx>
Date: Fri, 8 Jul 2011 14:40:13 -0700

>> Inside pstore_dump(), the first thing it tries to grab is a mutex_lock()
>> (inside an nmi hander).  This seems to be the root cause of my problems.
> 
> Someone else pointed out that mutex_lock() is a problem here too. They
> wondered whether spin_lock_irqsave() would work - or whether pstore
> backends were allowed to sleep - to which I said I hoped they didn't,
> but wasn't really sure what the future will hold.
> 
> So ... ideas (and patches) are most welcome.

Probably you'll need to queue things atomically using something
based upon cmpxchg() like the generic ring buffer does.
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