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authorJiri Kosina <jkosina@suse.cz>2014-09-03 15:04:28 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-17 09:03:59 -0700
commit4f6a1e6210f5aeed2832d69103fc6511c0ca7c2d (patch)
treeef8f3feda7804143d3f3870db51734d65568130b
parentc55d35d2b8fc84218785cf12dd3e895bc83af66d (diff)
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ACPI / cpuidle: fix deadlock between cpuidle_lock and cpu_hotplug.lock
commit 6726655dfdd2dc60c035c690d9f10cb69d7ea075 upstream. 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> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 4056d317517..a88894190e4 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1101,9 +1101,9 @@ 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) {
@@ -1130,8 +1130,8 @@ 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;