linux-kernel - Re: [PATCH] TCO watchdog pretimeout handler

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Message-ID: <20150615182941.GA19721@roeck-us.net>
Date:	Mon, 15 Jun 2015 11:29:41 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Francois-Nicolas Muller <francois-nicolas.muller@...el.com>
Cc:	wim@...ana.be, linux-watchdog@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] TCO watchdog pretimeout handler

On Mon, Jun 15, 2015 at 05:00:29PM +0200, Francois-Nicolas Muller wrote:
> Use TCO watchdog first timeout (pretimeout) to dump CPU backtraces and ease
> debug of watchdog expiration causes.
> TCO logic generates a SCI interrupt, then its handler dumps all CPU backtraces
> and calls panic (in order to execute registered panic callbacks).
> SCI interrupt number (GPE) is configured from ACPI tables.
> 
> Change-Id: If7badb962008ff38560a02575d0d41f6aaa5f7fd

ERROR: Remove Gerrit Change-Id's before submitting upstream.

I am unable to apply your patch to any version of the kernel
I can think of. Please rebase to the latest mainline, or at least
to a recent tag and let us know what it is based on. If it depends
on some other patch which needs to be applied first, please let us
know which one.

If I recall correctly, the iTCO watchdog can also generate an NMI.
Would it make sense to add support for handling this NMI as well ?

Some more minor comments below.

Thanks,
Guenter

> Signed-off-by: Francois-Nicolas Muller <francois-nicolas.muller@...el.com>
> ---
>  drivers/watchdog/iTCO_wdt.c | 51 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
> 
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index cf8c50d..3dd4175 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -67,6 +67,8 @@
>  #include <linux/io.h>			/* For inb/outb/... */
>  #include <linux/mfd/core.h>
>  #include <linux/mfd/lpc_ich.h>
> +#include <linux/nmi.h>
> +#include <linux/acpi.h>
>  
>  #include "iTCO_vendor.h"
>  
> @@ -124,6 +126,13 @@ module_param(turn_SMI_watchdog_clear_off, int, 0);
>  MODULE_PARM_DESC(turn_SMI_watchdog_clear_off,
>  	"Turn off SMI clearing watchdog (depends on TCO-version)(default=1)");
>  
> +#define DEFAULT_PRETIMEOUT 0
> +static bool pretimeout = DEFAULT_PRETIMEOUT;
> +module_param(pretimeout, bool, 0);
> +MODULE_PARM_DESC(pretimeout,
> +	"Enable watchdog pretimeout (default="
> +	__MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
> +

CHECK: Alignment should match open parenthesis

>  static int iTCO_wdt_active = 0;
>  
>  /*
> @@ -200,6 +209,45 @@ static int iTCO_wdt_unset_NO_REBOOT_bit(void)
>  	return ret; /* returns: 0 = OK, -EIO = Error */
>  }
>  
> +static unsigned char *tco_hid = "8086229C";
> +
> +static u32 iTCO_wdt_pretimeout_handler(acpi_handle gpe_device, u32 gpe,
> +					void *context)

CHECK: Alignment should match open parenthesis

> +{
> +	/* dump backtraces for all available cores */
> +	trigger_all_cpu_backtrace();
> +
> +	/* call panic notifiers */
> +	panic("Kernel Watchdog");
> +
> +	return ACPI_INTERRUPT_HANDLED;
> +}
> +
> +static acpi_status __init iTCO_wdt_register_gpe(acpi_handle handle,
> +					u32 lvl, void *context, void **rv)
> +{
> +	unsigned long long gpe;
> +	acpi_status status;
> +	union acpi_object object = { 0 };
> +	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };
> +
> +	status = acpi_evaluate_object(handle, "_GPE", NULL, &buffer);
> +	if (ACPI_FAILURE(status))
> +		return status;
> +
> +	if (object.type != ACPI_TYPE_INTEGER)
> +		return AE_BAD_DATA;
> +
> +	gpe = object.integer.value;
> +	status = acpi_install_gpe_handler(NULL, gpe, ACPI_GPE_EDGE_TRIGGERED,
> +					  iTCO_wdt_pretimeout_handler, NULL);
> +	if (ACPI_FAILURE(status))
> +		return status;
> +
> +	acpi_enable_gpe(NULL, gpe);
> +	return AE_OK;
> +}
> +
>  static int iTCO_wdt_start(struct watchdog_device *wd_dev)
>  {
>  	unsigned int val;
> @@ -625,6 +673,9 @@ static int __init iTCO_wdt_init_module(void)
>  	if (err)
>  		return err;
>  
> +	if (pretimeout)
> +		acpi_get_devices(tco_hid, iTCO_wdt_register_gpe, NULL, NULL);
> +
>  	return 0;
>  }
>  
> -- 
> 1.9.1
> 
> --
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