Re: tickle nmi watchdog whilst doing serial writes.

Russell King
2005-05-15T14:01:16Z

On Sun, May 15, 2005 at 02:20:14PM +0200, Andi Kleen wrote:
> Then someone needs to convince Linus to export touch_nmi_watchdog
> again.
>
> Or how about checking if interrupts are off here (iirc we have
> a generic function for that now) and then using
> a smaller timeout and otherwise schedule_timeout() ?

The interrupt state doesn't tell us whether we can schedule. It
tells us when we can't schedule, which is different from when we
can. For example:

spin_lock(foo_lock);
...
printk("blah blah blah\n");
...
spin_unlock(foo_lock);

This context is non-preemptable, but doesn't have IRQs disabled.
The solution would be to keep a "spinlock depth" counter, but
obviously that's not a possibility.

I would agree that the most correct thing to do would be to export
touch_nmi_watchdog()... if only Linus would accept the arguments
_for_ exporting it.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core