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Date: Tue, 13 Jul 2004 02:44:23 -0700
From: Andrew Morton <akpm@osdl.org>
To: Takashi Iwai <tiwai@suse.de>
Cc: rlrevell@joe-job.com, linux-audio-dev@music.columbia.edu, mingo@elte.hu,
       arjanv@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [linux-audio-dev] Re: [announce] [patch] Voluntary Kernel
 Preemption Patch
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Takashi Iwai <tiwai@suse.de> wrote:
>
> > You can do unlock_kernel()/lock_kernel() in soundcore_open().
> 
>  I remember ioctl() is also in lock_kernel()?

yes, you'll need to do unlock_kernel/lock_kernel there too.  If someone
changes the rules, or otherwise calls your ioctl withoht lock_kernel() held
it will reliably go BUG with spinlock debugging enabled, so make sure you
test with CONFIG_DEBUG_SPINLOCK=y.