msm: cpufreq: fix a race between hotplug and cpufreq
When msm_cpufreq_target() is called without holding the policy
semaphore, there is a rare chance that the cpu gets hotplugged in
the acpuclk_set_rate. The probability of this issue increases
when cross-calling is used or using interactive governor which
tries to set all cpu frequencies from a single thread.
Add a hotplug notifier and set the device_suspended flag holding
the suspend mutex, when cpu is going down. This mutex is always
held when frequency changes are done.
Change-Id: Ide3aa6927ad60d2512d63761c51bb15117461250
Signed-off-by: Narayanan Gopalakrishnan <nargop@codeaurora.org>
(cherry picked from commit 56f5a6de7f2ab48ed0538da727ad52673fb801a2)
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
diff --git a/arch/arm/mach-msm/cpufreq.c b/arch/arm/mach-msm/cpufreq.c
index 0fa1e2d..05bd56ef 100644
--- a/arch/arm/mach-msm/cpufreq.c
+++ b/arch/arm/mach-msm/cpufreq.c
@@ -92,6 +92,34 @@
}
#ifdef CONFIG_SMP
+static int __cpuinit msm_cpufreq_cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ per_cpu(cpufreq_suspend, cpu).device_suspended = 0;
+ break;
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ mutex_lock(&per_cpu(cpufreq_suspend, cpu).suspend_mutex);
+ per_cpu(cpufreq_suspend, cpu).device_suspended = 1;
+ mutex_unlock(&per_cpu(cpufreq_suspend, cpu).suspend_mutex);
+ break;
+ case CPU_DOWN_FAILED:
+ case CPU_DOWN_FAILED_FROZEN:
+ per_cpu(cpufreq_suspend, cpu).device_suspended = 0;
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __refdata msm_cpufreq_cpu_notifier = {
+ .notifier_call = msm_cpufreq_cpu_callback,
+};
+
static void set_cpu_work(struct work_struct *work)
{
struct cpufreq_work_struct *cpu_work =
@@ -385,6 +413,7 @@
#ifdef CONFIG_SMP
msm_cpufreq_wq = create_workqueue("msm-cpufreq");
+ register_hotcpu_notifier(&msm_cpufreq_cpu_notifier);
#endif
register_pm_notifier(&msm_cpufreq_pm_notifier);