From: Stuart Hayes <Stuart_Hayes@xxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Stuart Hayes <Stuart_Hayes@xxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- drivers/acpi/acpi_pad.c | 7 ++++--- 1 file 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)); } -- 1.7.11.1.104.ge7b44f1
