Date: Wed, 2 Jun 2010 11:34:46 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: TAMUKI Shoichi <tamuki@linet.gr.jp>
Cc: Ingo Molnar <mingo@elte.hu>, Anton Blanchard <anton@samba.org>,
       Andi Kleen <andi@firstfloor.org>, Andy Green <andy@warmcat.com>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] panic: keep blinking in spite of long spin timer mode
Message-Id: <20100602113446.060847eb.akpm@linux-foundation.org>
In-Reply-To: <201005272156.AA00412@tamuki.linet.gr.jp>
References: <201005272156.AA00412@tamuki.linet.gr.jp>
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On Fri, 28 May 2010 06:56:45 +0900
TAMUKI Shoichi <tamuki@linet.gr.jp> wrote:

> To keep panic_timeout accuracy when running under a hypervisor, the
> current implementation only spins on long time (1 second) calls to
> mdelay.  That brings a good effect, but we must give up blinking even
> if we have a panic_blink.
> 
> This patch keeps blinking in spite of long spin timer mode.
> 
> We now have new kernel parameter (panic_longspin) to enable long spin
> timer mode when kernel panics.  This is to be used when running under
> a hypervisor (default is disable).

The whole panic-blink setup seems rather poorly thought out.

Would it not be better if a call to (*panic_blink)() were to simply set
the state of the LED and then return?  So callers can do

	int state = 0;

	for ( ; ; ) {
		(*panic_blink)(state);
		state ^= 1;
		mdelay(MSEC_PER_SEC);
	}

?
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