linux-kernel - [PATCH] [WATCHDOG] Fix kdump when using hpwdt

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Date:	Sun, 23 Nov 2008 14:15:24 +0100
From:	Bernhard Walle <bwalle@...e.de>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, wim@...ana.be, stable@...nel.org,
	Thomas.Mingarelli@...com, Bernhard Walle <bwalle@...e.de>,
	Thomas Mingarelli <thomas.mingarelli@...com>,
	Vivek Goyal <vgoyal@...hat.com>
Subject: [PATCH] [WATCHDOG] Fix kdump when using hpwdt

When the "hpwdt" module is loaded (even if the /dev/watchdog device is not
opened), then kdump does not work. The panic kernel either does not start at
all or crash in various places.

The problem is that hpwdt_pretimeout is registered with register_die_notifier()
with the highest possible priority. Because it returns NOTIFY_STOP, the
crash_nmi_callback which is also registered with register_die_notifier() is
never executed. This causes the shutdown of other CPUs to fail.

Reverting the order is no option: The crash_nmi_callback executes HLT and so
never returns normally. Because of that, it must be executed as last notifier,
which currently is done.

So, that patch returns NOTIFY_OK to keep the crash_nmi_callback executed.

Signed-off-by: Bernhard Walle <bwalle@...e.de>
Cc: Wim Van Sebroeck <wim@...ana.be>
Cc: Thomas Mingarelli <thomas.mingarelli@...com>
Cc: Vivek Goyal <vgoyal@...hat.com>
---
 drivers/watchdog/hpwdt.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index a3765e0..21fe202 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -482,7 +482,7 @@ static int hpwdt_pretimeout(struct notifier_block *nb, unsigned long ulReason,
 			"Management Log for details.\n");
 	}

-	return NOTIFY_STOP;
+	return NOTIFY_OK;
 }

 /*
-- 
1.6.0.2

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