The system can continue running after the image is created, for
example because userspace cancelled the hibernation or only
saved the image for a dual mode disk + ram suspend. We must
restore the platform to the pre_snapshot state in this case.
This fixes a long standing bug in the acpi_cpufreq driver
which would fail after a cancelled hibernate because the
system then was running with the EC blocked:
cpufreq: adding CPU 1
acpi_cpufreq_cpu_init
cpufreq: FREQ: 1401000 - CPU: 0
ACPI Exception: AE_BAD_PARAMETER, Returned by Handler for [EmbeddedControl] (20130725/evregion-287)
ACPI Error: Method parse/execution failed [\_SB_.PCI0.LPC_.EC__.LPMD] (Node ffff88023249ab28), AE_BAD_PARAMETER (20130725/psparse-536)
ACPI Error: Method parse/execution failed [\_PR_.CPU0._PPC] (Node ffff88023270e3f8), AE_BAD_PARAMETER (20130725/psparse-536)
ACPI Error: Method parse/execution failed [\_PR_.CPU1._PPC] (Node ffff88023270e290), AE_BAD_PARAMETER (20130725/psparse-536)
ACPI Exception: AE_BAD_PARAMETER, Evaluating _PPC (20130725/processor_perflib-140)
cpufreq: initialization failed
CPU1 is up
Signed-off-by: Bjørn Mork <bjorn@xxxxxxx>
---
This is posted as RFC because I am unsure whether this is the correct
way to fix the problem. We definitely need to undo some of the
pre_snapshot work to have a fully functional system when create_image
returns, but I guess there can be unwanted side effects of unconditionally
calling platform_leave() like this.
FWIW, this works for me.
Testing and verifying the original acpi_cpufreq problem should be easy on
any system using that driver and having an EC, which should include most
laptops:
- Start a userspace hibernation and cancel it, for example by using
s2disk from uswsusp and pressing backspace.
The cpufreq device will disappear from all non-boot cores, and the above
ACPI exceptions will be logged.
Comments and/or alternative solutions are appreciated.
Note that the final solution to this problem should be backported to all
maintained stable kernels. I've verified that the problem exists and that
this proposed patch applies to 3.2, 3.4, 3.10 and 3.12
Bjørn
kernel/power/hibernate.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 0121dab83f43..59fb7e82f818 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -293,10 +293,10 @@ static int create_image(int platform_mode)
error);
/* Restore control flow magically appears here */
restore_processor_state();
- if (!in_suspend) {
+ if (!in_suspend)
events_check_enabled = false;
- platform_leave(platform_mode);
- }
+
+ platform_leave(platform_mode);
Power_up:
syscore_resume();
--
1.7.10.4
--
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