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acpi_pad: fix power_saving thread deadlock

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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>
This commit is contained in:
Stuart Hayes 2012-06-13 16:10:45 -05:00 committed by Len Brown
parent 76e10d158e
commit 5f16012610
1 changed files with 4 additions and 3 deletions
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7
drivers/acpi/acpi_pad.c
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@ -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));
}