From: Stuart Hayes Date: Wed, 13 Jun 2012 21:10:45 +0000 (-0500) Subject: acpi_pad: fix power_saving thread deadlock X-Git-Tag: v3.0.37~40 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c69499a1c8b4925248598f6eebf524968f92414f;p=karo-tx-linux.git acpi_pad: fix power_saving thread deadlock commit 5f1601261050251a5ca293378b492a69d590dacb upstream. 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 Signed-off-by: Stuart Hayes Signed-off-by: Len Brown Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c index a43fa1a57d57..1502c50273b5 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)); }