Re: NULL pointer dereference when 'rmmod gpio_lynxpoint'

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Thu, May 12, 2016 at 06:35:20AM -0700, Anatol Pomozov wrote:
> I use Chromebox with Matt's coreboot firmware and Arch Linux that
> currently compiles LYNX gpio as a module.
>
> There are 2 crashes:
> 1) ~25% chance of crash at boot time. Just boot the device and the
> system crashes when tries to probe the driver
> 2) system crashes when try to 'rmmod'. See stack trace in the first
> message of this thread.

I tried pretty much the same on a Broadwell based machine (uses the same
GPIO driver) and I did not see any crashes. I don't have Haswell based
machines around anymore.

Since you seem to be able get it crashing pretty easily, I wonder if you
can try following to debug the first crash:

 1. Blacklist gpio-lynxpoint
 2. Boot the system
 3. Send me contents of /proc/interrupts and /sys/kernel/debug/gpio
 4. Run 'insmod gpio-lynxpoint.ko'
 5. Send me full dmesg of the crash (if you can get it).

And the second crash:

 1. Remoge gpio-lynxpoint from blacklist
 2. Boot the system
 3. Run 'rmmod gpio-lynxpoint'
 4. Send me full dmesg of the crash (if you can get it).

Hopefully with that information we can find root cause of both crashes
(which may be the same).