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 20:58:45 +0300 [thread overview]
Message-ID: <4B2136D5.1030402@gmail.com> (raw)
In-Reply-To: <20091210100907.GA2446@ucw.cz>
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?
Thanks,
Alex.
Pavel Machek пишет:
> On Fri 2009-12-04 12:26:00, Xiaotian Feng wrote:
>
>> commit 8bd108d adds preemption point after each opcode parse, then
>> a sleeping function called from invalid context bug was founded
>> during suspend/resume stage. this was fixed in commit abe1dfa by
>> don't cond_resched when irq_disabled. But recent commit 138d156 changes
>> the behaviour to don't cond_resched when in_atomic. This makes the
>> sleeping function called from invalid context bug happen again, which
>> is reported in http://lkml.org/lkml/2009/12/1/371.
>>
>> The fix is to cond_sched() only when preemptible, which means not in
>> irq_disabled or in_atomic.
>>
>> @@ -152,7 +152,7 @@ static inline void *acpi_os_acquire_object(acpi_cache_t * cache)
>> #include <linux/hardirq.h>
>> #define ACPI_PREEMPTION_POINT() \
>> do { \
>> - if (!in_atomic_preempt_off()) \
>> + if (preemptible()) \
>> cond_resched(); \
>> } while (0)
>>
>
> Note that this is ugly as hell. It means we have two acpi
> interpretters in kernel, one for preemptible, one for non-preemptible,
> with very different behaviour.
>
> It would be slightly nicer to pass the "preemptible" info explicitely,
> as function parameters.
>
> It would be even better not to need that difference.
>
> Pavel
>
next prev parent reply other threads:[~2009-12-10 17:58 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 ` Alexey Starikovskiy [this message]
2009-12-10 18:18 ` [PATCH] ACPICA: don't cond_resched() when irq_disabled or in_atomic Pavel Machek
2009-12-10 18:37 ` Alexey Starikovskiy
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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