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authorJiri Kosina <jkosina@suse.cz>2014-09-03 17:04:28 +0400
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-09-04 01:05:55 +0400
commit6726655dfdd2dc60c035c690d9f10cb69d7ea075 (patch)
tree911f2815276b78131592c4c5f1e1992819af685a /drivers/acpi/processor_idle.c
parent69e273c0b0a3c337a521d083374c918dc52c666f (diff)
downloadlinux-6726655dfdd2dc60c035c690d9f10cb69d7ea075.tar.xz
ACPI / cpuidle: fix deadlock between cpuidle_lock and cpu_hotplug.lock
There is a following AB-BA dependency between cpu_hotplug.lock and cpuidle_lock: 1) cpu_hotplug.lock -> cpuidle_lock enable_nonboot_cpus() _cpu_up() cpu_hotplug_begin() LOCK(cpu_hotplug.lock) cpu_notify() ... acpi_processor_hotplug() cpuidle_pause_and_lock() LOCK(cpuidle_lock) 2) cpuidle_lock -> cpu_hotplug.lock acpi_os_execute_deferred() workqueue ... acpi_processor_cst_has_changed() cpuidle_pause_and_lock() LOCK(cpuidle_lock) get_online_cpus() LOCK(cpu_hotplug.lock) Fix this by reversing the order acpi_processor_cst_has_changed() does thigs -- let it first execute the protection against CPU hotplug by calling get_online_cpus() and obtain the cpuidle lock only after that (and perform the symmentric change when allowing CPUs hotplug again and dropping cpuidle lock). Spotted by lockdep. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Cc: All applicable <stable@vger.kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/processor_idle.c')
-rw-r--r--drivers/acpi/processor_idle.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 3dca36d4ad26..17f9ec501972 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1071,9 +1071,9 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) {
- cpuidle_pause_and_lock();
/* Protect against cpu-hotplug */
get_online_cpus();
+ cpuidle_pause_and_lock();
/* Disable all cpuidle devices */
for_each_online_cpu(cpu) {
@@ -1100,8 +1100,8 @@ int acpi_processor_cst_has_changed(struct acpi_processor *pr)
cpuidle_enable_device(dev);
}
}
- put_online_cpus();
cpuidle_resume_and_unlock();
+ put_online_cpus();
}
return 0;