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Date: Sat, 24 Nov 2007 22:39:20 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: youquan_song@linux.intel.com
Cc: linux-kernel@vger.kernel.org, Corey Minyard <minyard@acm.org>,
       Wim Van Sebroeck <wim@iguana.be>
Subject: Re: ipmi_watchdog can not reset the kernel panic machine
Message-Id: <20071124223920.212b36e3.akpm@linux-foundation.org>
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On Fri, 23 Nov 2007 20:28:41 -0800 (PST) youquan_song@linux.intel.com wrote:

> Build kernel-2.6.24-rc3.  pmi_watchdog can not reset the kernel panic
> machine.  The watchdog can never to record panic information to IPMI SEL.
> 
> 1. I disable auto reset when kernel panic by echo "0" >
> /proc/sys/kernel/panic
> 
> 2.  modprobe ipmi_watchdog timeout=120 action=reset
> 
> 3.  Load a driver, the driver will call panic() when  ioctl to call into
> the driver.
> 
> 4.  By ioctl call into the driver,  panic the system.
> 
> in wdog_panic_handler, I printk "ipmi_watchdog_state=WDOG_TIMEOUT_NONE"
> so, the watchdog can never to record panic information to IPMI SEL.
> 
> 
> static int wdog_panic_handler(struct notifier_block *this,
> 			      unsigned long         event,
> 			      void                  *unused)
> {
> 	static int panic_event_handled = 0;
> 
> 	/* On a panic, if we have a panic timeout, make sure to extend
> 	   the watchdog timer to a reasonable value to complete the
> 	   panic, if the watchdog timer is running.  Plus the
> 	   pretimeout is meaningless at panic time. */
> 	if (watchdog_user && !panic_event_handled &&
> 	    ipmi_watchdog_state != WDOG_TIMEOUT_NONE) {
> 		/* Make sure we do this only once. */
> 		panic_event_handled = 1;
> 
> 		timeout = 255;
> 		pretimeout = 0;
> 		panic_halt_ipmi_set_timeout();
> 	}
> 
> 	return NOTIFY_OK;
> }