linux-kernel - Re: [PATCH] ACPICA: don't cond_resched() when irq_disabled or in

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Message-ID: <20091211173333.GB15760@elf.ucw.cz>
Date:	Fri, 11 Dec 2009 18:33:33 +0100
From:	Pavel Machek <pavel@....cz>
To:	Alexey Starikovskiy <aystarik@...il.com>
Cc:	Xiaotian Feng <dfeng@...hat.com>, lenb@...nel.org,
	ming.m.lin@...el.com, robert.moore@...el.com,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPICA: don't cond_resched() when irq_disabled or
 in_atomic

On Thu 2009-12-10 21:37:59, Alexey Starikovskiy wrote:
> Pavel Machek ??????????:
> > On Thu 2009-12-10 20:58:45, Alexey Starikovskiy wrote:
> >   
> >> Hi Pavel,
> >>
> >> Please elaborate... Your comments "ugly as hell" are too often to be
> >> specific...
> >> There is only one use of ACPI_PREEMPTION_POINT(), and it is in the
> >> ACPICA code,
> >> which we all agreed to keep OS independent, thus the need for #define.
> >> Do you see any other way to add preemption point without introducing
> >> Linux-specific
> >> code into ACPICA?
> >>     
> >
> > I believe we want linux-specific code in acpica at this point.
> >
> >   
> The point there we call cond_resched() in ACPICA is an interpreter parse
> loop. This parse loop may be executed from within atomic context and even
> with interrupts off. In this case, cond_resched() should not be called
> to not make
> might_sleep() guards angry.

Yes, so pass explicit argument to the interpretter, telling it what
kind of context it runs on. Similar to kmalloc's GFP_KERNEL
vs. GFP_ATOMIC.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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