Kernel Bug Tracker – Bug 6612
S3: resume poweroff due to outstanding button event
Last modified: 2006-06-25 21:37:19 UTC
Most recent kernel where this bug did not occur: n/a
Distribution: Mainline 184.108.40.206 + acpi-release-20060310-2.6.16 patches
Hardware Environment: Thinkpad T43 2687
Software Environment: Debian
Resuming from S3 (suspend-to-ram) using the power button causes a stray
power-button event which shutdowns the machine. Apparently, ACPI 3.0 P62 says
the kernel should be cleaning up the stray powerbutton event, instead of letting
userspace deal with the mess.
There is an analysis and patch about this issue at
I am just reporting the bug (which I verified), and the possible solution by Mr.
Arnaud Patard in the above mentioned post.
Steps to reproduce:
boot with a kernel using acpi_sleep=s3_bios
do echo mem > /sys/power/state (preferably using a properly setup hibernate
wake machine up using the power button
Created attachment 8201 [details]
patch from Arnaud Patard: delete powerbutton event after resume from S3
Patch and analysis by Arnaud Patard <apatard <at> mandriva.com>, posted to:
This is a downside in the patch. 'acpi_clear_event' isn't supposed to be
called with interrupt disabled (it uses mutex).
Can't the code be modifed to use a semasphore of some sort, so that it supresses
the powerbutton event after the mutex is released?
Reply to comment #2:
Calling acpi_set_register() with ACPI_MTX_DO_NOT_LOCK instead of calling
acpi_clear_event() would be better ?
Yes, I agree acpi_set_register() is the right way.
Created attachment 8223 [details]
Incremental patch using acpi_set_register instead of acpi_clear_event
This is an incremental version but I can send a full version if preferred :)
It's a bit nasty to use a global variable within ACPICA,
While the patch in comment #6 treats the symptom, the proper
fix is to enable acpi_clear_event() to be called
from interrupt context.
To do that, the semaphore that acpi_set_register() uses
needs to be replaced by a spin-lock. Fixing that is the
subject of bug #6634
Ok. So, we'll have to wait having a fix for the bug #6634 ?
Or one may change the acpi_clear_event prototype to get a second argument
(ACPI_MTX_DO_NOT_LOCK or ACPI_MTX_LOCK) (I admit that this change of prototype
is a ugly workaround :/ ) ?
ACPICA 20060608 replaced the mutex in acpi_set_register()
with a spin-lock, so the original patch in comment #1
no longer needs to be modified.
shipped in 2.6.17-git9, closed.