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SubjectRe: [PATCH 3/3] hpwdt: Use nmi_panic() when kernel panics in NMI handler
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On 02/29/2016 05:50 PM, Hidehiro Kawai wrote:
> commit 58c5661f2144 ("panic, x86: Allow CPUs to save registers even
> if looping in NMI context") introduced nmi_panic() which prevents
> concurrent/recursive execution of panic(). It also saves registers
> for the crash dump on x86.
>
> hpwdt driver can call panic() from NMI handler, so replace it with
> nmi_panic().
>
> Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
> Cc: Thomas Mingarelli <thomas.mingarelli@hpe.com>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: linux-watchdog@vger.kernel.org
> ---
> drivers/watchdog/hpwdt.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
> index 92443c3..fd0486f 100644
> --- a/drivers/watchdog/hpwdt.c
> +++ b/drivers/watchdog/hpwdt.c
> @@ -496,11 +496,12 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
>
> if (!is_icru && !is_uefi) {
> if (cmn_regs.u1.ral == 0) {
> - panic("An NMI occurred, "
> + nmi_panic(regs, "An NMI occurred, "
> "but unable to determine source.\n");

This message should really be in a single line.
Sure, strictly speaking that should be done in a separate patch,
but since you touch the line you might as well fix it.

> + goto handled;

The goto is unnecessary. Just return NMI_HANDLED.

> }
> }
> - panic("An NMI occurred. Depending on your system the reason "
> + nmi_panic(regs, "An NMI occurred. Depending on your system the reason "
> "for the NMI is logged in any one of the following "
> "resources:\n"
> "1. Integrated Management Log (IML)\n"
> @@ -508,6 +509,13 @@ static int hpwdt_pretimeout(unsigned int ulReason, struct pt_regs *regs)
> "3. OA Forward Progress Log\n"
> "4. iLO Event Log");
>
> +handled:
> + /*
> + * Returning from nmi_panic() means this CPU was processing panic()
> + * before NMI. Return NMI_HANDLED and go back to panic routines.
> + */

I don't think this comment adds much if any value.

> + return NMI_HANDLED;
> +
> out:

Any goto to this label does no longer serve a useful purpose (if it ever served one),
and should be replaced with "return NMI_DONE;"

> return NMI_DONE;
> }
>
>
>

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