[BUG] sbs module causes lockup upon suspend/shutdown

[Armin Wolf]

Hello,

on my Travelmate 4002WLMI, the sbs module causes a lockup upon suspend/shutdown when loaded.
Additionally, a kernel oops occurs when unloading the sbs module with "modprobe -r sbs", but
not with "rmmod sbs".

While i was able to fix the oops on module removal (a race condition similar to 757c968c4423,
but now inside the ACPI EC driver), i was unable to find the cause for the lockup.

I did however find out that the lockup does not occur when i reset the EC SMBus alert flag
before calling the handler function, to i suppose the issue lies inside the sbs alert callback
(maybe similar to add68d6aa9e2).

I created a bug report (https://bugzilla.kernel.org/show_bug.cgi?id=217041) with more information
attached, such as dmesg logs. Any  ideas on what causes the lockup?

Armin Wolf