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From: "Zdenek Kabelac" <>
To: "Ingo Molnar" <>
Cc: "Linux Kernel Mailing List" <>,
	"Peter Zijlstra" <>
Subject: Re: sys_sched_yield keeps locked irq before call of schedule()
Date: Wed, 5 Nov 2008 14:09:36 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

2008/11/5 Ingo Molnar <>:
> * Zdenek Kabelac <> wrote:
>> Hi
>> With recent 2.6.28-rc3 kernel I've noticed that schedule() is
>> sometime being called with locked IRQ
>> Call Trace:
>>  [<ffffffff81334592>] _spin_lock_irq+0x92/0xa0
>>  [<ffffffff8133126b>] schedule+0x13b/0x4cb
>>  [<ffffffff81013c10>] ? native_sched_clock+0x70/0xa0
>>  [<ffffffff81040930>] ? sys_sched_yield+0x0/0x80
>>  [<ffffffff810409a5>] sys_sched_yield+0x75/0x80
>>  [<ffffffff8100c6bb>] system_call_fastpath+0x16/0x1b
> is this some special warning you added? The stock kernel certainly
> does not emit this warning.

Yes - it's my personal debug checker that tries to watch wether irq &
irqsafe are running in pair.
So it shows a warning if there is a call of spin_lock_irq and irq is
already dissabled.

>> Which is a result of the function sys_sched_yield() that calls
>> schedule() while it keeps irq.
>> Is it correct to call the function schedule() which 'usually'
>> expects irq being unlocked and do some 'lenghty' operations (i.e.
>> debug statistics) which do not need to keep irq locked for such a
>> long time?
> the debug statistics are all fast and we disable interrupts straight
> away when entering the schedule().

IRQ is disabled with spin_lock_irc() inside schedule() and it looks
like there is quite a few lines above which receive 'extra' bonus with
being run without enabled irq, but as I said - I'm just checking
whether this is intentional or not.


  reply	other threads:[~2008-11-05 13:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-05 12:57 Zdenek Kabelac
2008-11-05 13:01 ` Ingo Molnar
2008-11-05 13:09   ` Zdenek Kabelac [this message]
2008-11-05 14:05     ` Arnd Bergmann
2008-11-05 14:37       ` Zdenek Kabelac
2008-11-06  7:57     ` Ingo Molnar
2008-11-06 13:46       ` Steven Rostedt
2008-11-06 14:34         ` Ingo Molnar
2008-11-06 14:46           ` Steven Rostedt

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