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authorThomas Gleixner <tglx@linutronix.de>2008-07-28 01:47:12 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-28 19:31:58 +0400
commitb032bf70df2e43149ce2b4e9a865b076c6140753 (patch)
treeba022a0bc85598a29e21b7aa3f101c8043c24024 /drivers/acpi
parent9ffc1699e36abd5baee188c8e36b1bb27d0d4278 (diff)
downloadlinux-b032bf70df2e43149ce2b4e9a865b076c6140753.tar.xz
ACPI/CPUIDLE: prevent setting pm_idle to NULL
pm_idle_save resp. pm_idle_old can be NULL when the restore code in acpi_processor_cst_has_changed() resp. cpuidle_uninstall_idle_handler() is called. This can set pm_idle unconditinally to NULL, which causes the kernel to panic when calling pm_idle in the x86 idle code. This was covered by an extra check for !pm_idle in the x86 idle code, which was removed during the x86 idle code refactoring. Instead of restoring the pm_idle check in the x86 code prevent the acpi/cpuidle code to set pm_idle to NULL. Reported by: Dhaval Giani http://lkml.org/lkml/2008/7/2/309 Based on a debug patch from Ingo Molnar Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/processor_idle.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index b7f2963693a7..283c08f5f4d4 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1332,9 +1332,15 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
if (!pr->flags.power_setup_done)
return -ENODEV;
- /* Fall back to the default idle loop */
- pm_idle = pm_idle_save;
- synchronize_sched(); /* Relies on interrupts forcing exit from idle. */
+ /*
+ * Fall back to the default idle loop, when pm_idle_save had
+ * been initialized.
+ */
+ if (pm_idle_save) {
+ pm_idle = pm_idle_save;
+ /* Relies on interrupts forcing exit from idle. */
+ synchronize_sched();
+ }
pr->flags.power = 0;
result = acpi_processor_get_power_info(pr);
@@ -1896,7 +1902,8 @@ int acpi_processor_power_exit(struct acpi_processor *pr,
/* Unregister the idle handler when processor #0 is removed. */
if (pr->id == 0) {
- pm_idle = pm_idle_save;
+ if (pm_idle_save)
+ pm_idle = pm_idle_save;
/*
* We are about to unload the current idle thread pm callback