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authorStuart Hayes <Stuart_Hayes@Dell.com>2012-06-13 21:10:45 (GMT)
committerAntti Palosaari <crope@iki.fi>2012-07-03 19:57:28 (GMT)
commit749eb40b46492ead6f0ae334bb51332607469538 (patch)
tree9c6bb70e6fc979ba7a8de9326f312a9add6bcbe2
parente70b342f9a97040c3a70db4cf82b7662e51f194d (diff)
acpi_pad: fix power_saving thread deadlock
The acpi_pad driver can get stuck in destroy_power_saving_task() waiting for kthread_stop() to stop a power_saving thread. The problem is that the isolated_cpus_lock mutex is owned when destroy_power_saving_task() calls kthread_stop(), which waits for a power_saving thread to end, and the power_saving thread tries to acquire the isolated_cpus_lock when it calls round_robin_cpu(). This patch fixes the issue by making round_robin_cpu() use its own mutex. https://bugzilla.kernel.org/show_bug.cgi?id=42981 Cc: stable@vger.kernel.org Signed-off-by: Stuart Hayes <Stuart_Hayes@Dell.com> Signed-off-by: Len Brown <len.brown@intel.com>
-rw-r--r--drivers/acpi/acpi_pad.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index a43fa1a..1502c502 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -36,6 +36,7 @@
#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
static DEFINE_MUTEX(isolated_cpus_lock);
+static DEFINE_MUTEX(round_robin_lock);
static unsigned long power_saving_mwait_eax;
@@ -107,7 +108,7 @@ static void round_robin_cpu(unsigned int tsk_index)
if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
return;
- mutex_lock(&isolated_cpus_lock);
+ mutex_lock(&round_robin_lock);
cpumask_clear(tmp);
for_each_cpu(cpu, pad_busy_cpus)
cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
@@ -116,7 +117,7 @@ static void round_robin_cpu(unsigned int tsk_index)
if (cpumask_empty(tmp))
cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
if (cpumask_empty(tmp)) {
- mutex_unlock(&isolated_cpus_lock);
+ mutex_unlock(&round_robin_lock);
return;
}
for_each_cpu(cpu, tmp) {
@@ -131,7 +132,7 @@ static void round_robin_cpu(unsigned int tsk_index)
tsk_in_cpu[tsk_index] = preferred_cpu;
cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
cpu_weight[preferred_cpu]++;
- mutex_unlock(&isolated_cpus_lock);
+ mutex_unlock(&round_robin_lock);
set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
}

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