suspicious behaviour in pcwd driver.

suspicious behaviour in pcwd driver.

[Dave Jones]

drivers/char/watchdog/pcwd.c does this if it detects
a temperature out of range..

            if (temp_panic) {
                printk (KERN_INFO PFX "Temperature overheat trip!\n");
                machine_power_off();
            }

Two problems here are..

1. machine_power_off() isn't exported on ppc64. (patch below)
2. that printk will never hit the logs, so the admin will just find
a powered off box with no idea what happened.
Should we at least sync block devices before doing the power off ?

		Dave



Export machine_power_off() on ppc64, as the pcwd watchdog driver needs it.

Signed-off-by: Dave Jones <davej@redhat.com>

--- linux-2.6.12/arch/ppc64/kernel/setup.c~	2005-08-09 17:37:36.000000000 -0400
+++ linux-2.6.12/arch/ppc64/kernel/setup.c	2005-08-09 17:37:53.000000000 -0400
@@ -706,6 +706,7 @@ void machine_power_off(void)
 	local_irq_disable();
 	while (1) ;
 }
+EXPORT_SYMBOL(machine_power_off);
 
 void machine_halt(void)
 {

Re: suspicious behaviour in pcwd driver.

[Dave Jones]

On Mon, Aug 22, 2005 at 02:30:06PM -0400, Dave Jones wrote:
 > drivers/char/watchdog/pcwd.c does this if it detects
 > a temperature out of range..
 > 
 >             if (temp_panic) {
 >                 printk (KERN_INFO PFX "Temperature overheat trip!\n");
 >                 machine_power_off();
 >             }
 > 
 > Two problems here are..
 > 
 > 1. machine_power_off() isn't exported on ppc64. (patch below)

I was looking at an old tree, and this is now kernel_power_off()
so this isn't a problem for pcwd, however the export is still needed
for drivers/macintosh/therm_pm72.c

 > 2. that printk will never hit the logs, so the admin will just find
 > a powered off box with no idea what happened.
 > Should we at least sync block devices before doing the power off ?

AFAICS, this is still a problem with kernel_power_off() though ?

		Dave

Re: suspicious behaviour in pcwd driver.

[Benjamin Herrenschmidt]

> Export machine_power_off() on ppc64, as the pcwd watchdog driver needs it.
> 
> Signed-off-by: Dave Jones <davej@redhat.com>
> 
> --- linux-2.6.12/arch/ppc64/kernel/setup.c~	2005-08-09 17:37:36.000000000 -0400
> +++ linux-2.6.12/arch/ppc64/kernel/setup.c	2005-08-09 17:37:53.000000000 -0400
> @@ -706,6 +706,7 @@ void machine_power_off(void)
>  	local_irq_disable();
>  	while (1) ;
>  }
> +EXPORT_SYMBOL(machine_power_off);
>  
>  void machine_halt(void)
>  {
> 

In fact, we need that for the G5 thermal driver too. I wonder why/how
this export got removed ... Some over-zealous janitors ?

Hrm... /me plays with gitk

Ahhh, ok, so that is this patch:

<<
machine_restart, machine_halt and machine_power_off are machine
    specific hooks deep into the reboot logic, that modules
    have no business messing with.  Usually code should be calling
    kernel_restart, kernel_halt, kernel_power_off, or
    emergency_restart. So don't export machine_restart,
    machine_halt, and machine_power_off so we can catch buggy users.
>>

Well, I think for now, it's safe for therm_pm72 to call
machine_power_off() in case of critical overtemp. I'll have a look at
kernel_* equivalents later.

Can you still slip that patch into 2.6.13 ?

Ben.

Re: suspicious behaviour in pcwd driver.

[Pavel Machek]

Hi!


>  > 2. that printk will never hit the logs, so the admin will just find
>  > a powered off box with no idea what happened.
>  > Should we at least sync block devices before doing the power off ?
> 
> AFAICS, this is still a problem with kernel_power_off() though ?
> 

Look at how acpi does this; we probably want to trigger clean shutdown.
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