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| author | Viresh Kumar <viresh.kumar@linaro.org> | 2013-01-12 05:14:40 (GMT) |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-02-01 23:01:14 (GMT) |
| commit | 6954ca9c8b5cbaf45c3e45a5a5a7450c6b55ab27 (patch) | |
| tree | a888e21ecf2e7d72b778826f39c71a96dcc9bfa7 /drivers/cpufreq/cpufreq.c | |
| parent | f6a7409cab3b525c5e55540e7cd08d23e198352f (diff) | |
| download | linux-6954ca9c8b5cbaf45c3e45a5a5a7450c6b55ab27.tar.xz | |
cpufreq: Don't use cpu removed during cpufreq_driver_unregister
This is how the core works:
cpufreq_driver_unregister()
- subsys_interface_unregister()
- for_each_cpu() call cpufreq_remove_dev(), i.e. 0,1,2,3,4 when we
unregister.
cpufreq_remove_dev():
- Remove policy node
- Call cpufreq_add_dev() for next cpu, sharing mask with removed cpu.
i.e. When cpu 0 is removed, we call it for cpu 1. And when called for cpu 2,
we call it for cpu 3.
- cpufreq_add_dev() would call cpufreq_driver->init()
- init would return mask as AND of 2, 3 and 4 for cluster A7.
- cpufreq core would do online_cpu && policy->cpus
Here is the BUG(). Because cpu hasn't died but we have just unregistered
the cpufreq driver, online cpu would still have cpu 2 in it. And so thing
go bad again.
Solution: Keep cpumask of cpus that are registered with cpufreq core and clear
cpus when we get a call from subsys_interface_unregister() via
cpufreq_remove_dev().
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index a0a33bd..034d183 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -47,6 +47,9 @@ static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor); #endif static DEFINE_SPINLOCK(cpufreq_driver_lock); +/* Used when we unregister cpufreq driver */ +static struct cpumask cpufreq_online_mask; + /* * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure * all cpufreq/hotplug/workqueue/etc related lock issues. @@ -981,6 +984,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) * managing offline cpus here. */ cpumask_and(policy->cpus, policy->cpus, cpu_online_mask); + cpumask_and(policy->cpus, policy->cpus, &cpufreq_online_mask); policy->user_policy.min = policy->min; policy->user_policy.max = policy->max; @@ -1064,7 +1068,6 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif } per_cpu(cpufreq_cpu_data, cpu) = NULL; - #ifdef CONFIG_SMP /* if this isn't the CPU which is the parent of the kobj, we * only need to unlink, put and exit @@ -1185,6 +1188,7 @@ static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) if (unlikely(lock_policy_rwsem_write(cpu))) BUG(); + cpumask_clear_cpu(cpu, &cpufreq_online_mask); retval = __cpufreq_remove_dev(dev, sif); return retval; } @@ -1903,6 +1907,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) cpufreq_driver = driver_data; spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + cpumask_setall(&cpufreq_online_mask); + ret = subsys_interface_register(&cpufreq_interface); if (ret) goto err_null_driver; |