Messages in this thread Patch in this message | | | From | Bernhard Walle <> | Subject | [PATCH] [WATCHDOG] Fix kdump when using hpwdt | Date | Sun, 26 Oct 2008 15:59:37 +0100 |
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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 in case allow_kdump is set as module parameter in the hpwdt module. Also, it changes the default of allow_kdump to 1. Kdump is quite common and should be working as default.
Signed-off-by: Bernhard Walle <bwalle@suse.de> Cc: Wim Van Sebroeck <wim@iguana.be> Cc: Thomas Mingarelli <thomas.mingarelli@hp.com> Cc: Vivek Goyal <vgoyal@redhat.com> --- drivers/watchdog/hpwdt.c | 10 +++++++--- 1 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c index a3765e0..65e7102 100644 --- a/drivers/watchdog/hpwdt.c +++ b/drivers/watchdog/hpwdt.c @@ -116,7 +116,7 @@ static unsigned int reload; /* the computed soft_margin */ static int nowayout = WATCHDOG_NOWAYOUT; static char expect_release; static unsigned long hpwdt_is_open; -static unsigned int allow_kdump; +static unsigned int allow_kdump = 1; static void __iomem *pci_mem_addr; /* the PCI-memory address */ static unsigned long __iomem *hpwdt_timer_reg; @@ -482,7 +482,11 @@ static int hpwdt_pretimeout(struct notifier_block *nb, unsigned long ulReason, "Management Log for details.\n"); } - return NOTIFY_STOP; + /* + * for kdump, we must return NOTIFY_OK here to execute the + * crash_nmi_callback afterwards, see arch/x86/kernel/crash.c + */ + return allow_kdump ? NOTIFY_OK : NOTIFY_STOP; } /* @@ -759,7 +763,7 @@ MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); module_param(soft_margin, int, 0); MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds"); -module_param(allow_kdump, int, 0); +module_param(allow_kdump, int, 1); MODULE_PARM_DESC(allow_kdump, "Start a kernel dump after NMI occurs"); module_param(nowayout, int, 0); -- 1.6.0.2
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