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Date: Wed, 14 Jul 2004 00:37:01 +0200
From: Andrea Arcangeli <andrea@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: paul@linuxaudiosystems.com, 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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On Tue, Jul 13, 2004 at 03:25:32PM -0700, Andrew Morton wrote:
> 	local_irq_disable();
> 	<fiddle with per-cpu stuff>
> 	function_which_calls_cond_resched();
> 	<fiddle with per-cpu stuff>
> 	local_irq_enable();
> 
> then we want might_sleep() to warn about the bug.

might_sleep currently _doesn't_ warn about any bug in the above case I
quoted.

the kmalloc example is trapped instead.

>>From my part I don't like anybody to call schedule with irq disabled
(and I would definitely put a debug check in schedule() for that, guess
how I found about the missing sti in entry.S btw). But if you are ok
with people calling schedule with irq disabled then I cannot put a check
in there. sti doesn't cost that much, and the work-to-do and sched_yield
paths are _never_ fast paths, so they don't worth an hack like that.