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Date: Mon, 21 Jun 2004 16:40:17 -0400
From: Nobuhiro Tachino <ntachino@redhat.com>
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To: Takao Indoh <indou.takao@soft.fujitsu.com>
CC: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Christoph Hellwig <hch@infradead.org>, Andi Kleen <ak@muc.de>
Subject: Re: [3/4] [PATCH]Diskdump - yet another crash dump function
References: <20040617121356.GA24338@elte.hu> <D3C4552C24A60Aindou.takao@soft.fujitsu.com>
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Takao Indoh wrote:
> On Thu, 17 Jun 2004 14:13:56 +0200, Ingo Molnar wrote:
> 
> 
>>but there's another possible method (suggested by Alan Cox) that
>>requires no changes to the timer API hotpaths: 'clear' all timer lists
>>upon a crash [once all CPUs have stopped and irqs are disabled] and just
>>let the drivers use the normal timer APIs. Drive timer execution via a
>>polling method.
>>
>>this basically approximates your polling based implementation but uses
>>the existing kernel timer data structures and timer mechanism so should
>>be robust and compatible. It doesnt rely on any previous state (because
>>all currently pending timers are discarded) so it's as crash-safe as
>>possible.
> 
> 
> This is a test patch for clearing timer/tasklet and executing it
> during dumping.
> This patch does not work yet. I tried dumping using this patch, but
> aic7xxx is unstable...

Your new dump_run_timers() calls __run_timers() directly. I think that's
the reason of unstability. __run_timers() calls spin_unlock_irq()
and enables IRQ, but diskdump expects everything runs with IRQ
disabled.