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Commit 5f1601261050251a5ca293378b492a69d590dacb

Authored by Stuart Hayes
Committed by Len Brown
1 parent 76e10d158e
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

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>

Showing 1 changed file with 4 additions and 3 deletions Side-by-side Diff

drivers/acpi/acpi_pad.c
Diff comments   View file @ 5f16012
... ... @@ -36,6 +36,7 @@
36 36 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
37 37 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
38 38 static DEFINE_MUTEX(isolated_cpus_lock);
  39 +static DEFINE_MUTEX(round_robin_lock);
39 40  
40 41 static unsigned long power_saving_mwait_eax;
41 42  
... ... @@ -107,7 +108,7 @@
107 108 if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
108 109 return;
109 110  
110   - mutex_lock(&isolated_cpus_lock);
  111 + mutex_lock(&round_robin_lock);
111 112 cpumask_clear(tmp);
112 113 for_each_cpu(cpu, pad_busy_cpus)
113 114 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
... ... @@ -116,7 +117,7 @@
116 117 if (cpumask_empty(tmp))
117 118 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
118 119 if (cpumask_empty(tmp)) {
119   - mutex_unlock(&isolated_cpus_lock);
  120 + mutex_unlock(&round_robin_lock);
120 121 return;
121 122 }
122 123 for_each_cpu(cpu, tmp) {
... ... @@ -131,7 +132,7 @@
131 132 tsk_in_cpu[tsk_index] = preferred_cpu;
132 133 cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
133 134 cpu_weight[preferred_cpu]++;
134   - mutex_unlock(&isolated_cpus_lock);
  135 + mutex_unlock(&round_robin_lock);
135 136  
136 137 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
137 138 }