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From: Alexey Starikovskiy <aystarik@gmail.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Xiaotian Feng <dfeng@redhat.com>,
	lenb@kernel.org, ming.m.lin@intel.com, robert.moore@intel.com,
	linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ACPICA: don't cond_resched() when irq_disabled or in_atomic
Date: Thu, 10 Dec 2009 21:37:59 +0300	[thread overview]
Message-ID: <4B214007.2080409@gmail.com> (raw)
In-Reply-To: <20091210181800.GM19454@elf.ucw.cz>

Pavel Machek пишет:
> 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.

Please post the code, which will do the above and will not look "ugly as
hell".
I still don't follow your vague comments.
> (Or maybe... I guess other systems have concept of preemption and not
> all actions are permitted from all contexts, so maybe something like
> that would be important for them, too?)
>   
None of them cared about it up to this point.
With the macro above we allowed them to follow Linux, but to go or not
is their call.

Regards,
Alex.

  reply	other threads:[~2009-12-10 18:37 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-04  4:26 [PATCH] ACPICA: don't cond_resched() when irq_disabled or in_atomic Xiaotian Feng
2009-12-04  5:36 ` Zhang Rui
2009-12-04  5:38   ` Zhang Rui
2009-12-04  6:50 ` Justin Mattock
2009-12-04  7:05   ` Danny Feng
2009-12-04  7:27     ` Justin P. Mattock
2009-12-09  1:54       ` Xiaotian Feng
2009-12-10 10:09 ` Pavel Machek
2009-12-10 11:56   ` [PATCH -V2] acpi: don't cond_resched if irq is disabled Xiaotian Feng
2009-12-10 12:21     ` Alexey Starikovskiy
2009-12-11  5:46       ` Lin Ming
2009-12-11 11:48         ` Alexey Starikovskiy
2009-12-11 16:15           ` Pavel Machek
2009-12-11 16:25             ` Alexey Starikovskiy
2009-12-11 17:34               ` Pavel Machek
2009-12-28  6:02                 ` Xiaotian Feng
2009-12-28 11:12                   ` Alexey Starikovskiy
2010-01-16  6:44                     ` Len Brown
2009-12-10 17:58   ` [PATCH] ACPICA: don't cond_resched() when irq_disabled or in_atomic Alexey Starikovskiy
2009-12-10 18:18     ` Pavel Machek
2009-12-10 18:37       ` Alexey Starikovskiy [this message]
2009-12-10 22:46         ` Justin P. Mattock
2009-12-10 22:54           ` Moore, Robert
2010-01-16  6:46             ` Len Brown
2009-12-11 17:33         ` Pavel Machek

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