Re: [PATCH V2 2/6] cpufreq: Remove cpufreq_frequency_get_table()

Hi Viresh,

On Thu, Jun 02, 2016 at 07:34:56PM +0530, Viresh Kumar wrote:

Most of the callers of cpufreq_frequency_get_table() already have the pointer to a valid 'policy' structure and they don't really need to go through the per-cpu variable first and then a check to validate the frequency, in order to find the freq-table for the policy.

Directly use the policy->freq_table field instead for them.

Only one user of that API is left after above changes, cpu_cooling.c and it accesses the freq_table in a racy way as the policy can get freed in between.

Fix it by using cpufreq_cpu_get() properly.

In 5a31d594a973 ("cpufreq: Allow freq_table to be obtained for offline CPUs") you did the opposite: don't use cpufreq_cpu_get_raw() because it won't give you the policy of a cpu that is offline. Now you are arguing that we should go back to cpufreq_cpu_get() which implicitly calls cpufreq_cpu_get_raw(). Won't we hit the same issue that 5a31d594a973 was trying to prevent: that we can't get a freq_table for a cpu that is offline?

Cheers, Javi

Signed-off-by: Viresh Kumar viresh.kumar@linaro.org

drivers/cpufreq/cpufreq.c | 38 +++++++++++++---------------------- drivers/cpufreq/cpufreq_ondemand.c | 2 +- drivers/cpufreq/cpufreq_stats.c | 3 +-- drivers/cpufreq/freq_table.c | 9 +++------ drivers/cpufreq/ppc_cbe_cpufreq_pmi.c | 3 +-- drivers/thermal/cpu_cooling.c | 22 +++++++++++++++----- include/linux/cpufreq.h | 2 -- 7 files changed, 37 insertions(+), 42 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index fbc97b1fa371..1833eda1f9d4 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -126,15 +126,6 @@ struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy) } EXPORT_SYMBOL_GPL(get_governor_parent_kobj); -struct cpufreq_frequency_table *cpufreq_frequency_get_table(unsigned int cpu) -{

• struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
• return policy && !policy_is_inactive(policy) ?

• policy->freq_table : NULL;
  

-} -EXPORT_SYMBOL_GPL(cpufreq_frequency_get_table);

static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall) { u64 idle_time; @@ -1950,7 +1941,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy, if (!cpufreq_driver->target_index) return -EINVAL;

• freq_table = cpufreq_frequency_get_table(policy->cpu);

• freq_table = policy->freq_table; if (unlikely(!freq_table)) { pr_err("%s: Unable to find freq_table\n", __func__); return -EINVAL;

@@ -2345,26 +2336,25 @@ static struct notifier_block __refdata cpufreq_cpu_notifier = { *********************************************************************/ static int cpufreq_boost_set_sw(int state) {

• struct cpufreq_frequency_table *freq_table; struct cpufreq_policy *policy; int ret = -EINVAL;

for_each_active_policy(policy) {

• freq_table = cpufreq_frequency_get_table(policy->cpu);
  

• if (freq_table) {
  

• 	ret = cpufreq_frequency_table_cpuinfo(policy,
  

• 					freq_table);
  

• 	if (ret) {
  

• 		pr_err("%s: Policy frequency update failed\n",
  

• 		       __func__);
  

• 		break;
  

• 	}
  

• if (!policy->freq_table)
  

• 	continue;
  

• 	down_write(&policy->rwsem);
  

• 	policy->user_policy.max = policy->max;
  

• 	cpufreq_governor_limits(policy);
  

• 	up_write(&policy->rwsem);
  

• ret = cpufreq_frequency_table_cpuinfo(policy,
  

• 				      policy->freq_table);
  

• if (ret) {
  

• 	pr_err("%s: Policy frequency update failed\n",
  

• 	       __func__);
  

• 	break;
  

  }

• down_write(&policy->rwsem);
  

• policy->user_policy.max = policy->max;
  

• cpufreq_governor_limits(policy);
  

• up_write(&policy->rwsem);
  

  }

return ret; diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index c84fc2240d49..4d2fe2710c5d 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -113,7 +113,7 @@ static void ondemand_powersave_bias_init(struct cpufreq_policy *policy) { struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);

• dbs_info->freq_table = cpufreq_frequency_get_table(policy->cpu);

• dbs_info->freq_table = policy->freq_table; dbs_info->freq_lo = 0;

} diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c index c6e7f81a0397..06d3abdffd3a 100644 --- a/drivers/cpufreq/cpufreq_stats.c +++ b/drivers/cpufreq/cpufreq_stats.c @@ -157,11 +157,10 @@ void cpufreq_stats_create_table(struct cpufreq_policy *policy) unsigned int i = 0, count = 0, ret = -ENOMEM; struct cpufreq_stats *stats; unsigned int alloc_size;

• unsigned int cpu = policy->cpu; struct cpufreq_frequency_table *pos, *table;

/* We need cpufreq table for creating stats table */

• table = cpufreq_frequency_get_table(cpu);

• table = policy->freq_table; if (unlikely(!table)) return;

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c index 4e5c5dbfed7a..f52b5473b1f4 100644 --- a/drivers/cpufreq/freq_table.c +++ b/drivers/cpufreq/freq_table.c @@ -106,12 +106,10 @@ EXPORT_SYMBOL_GPL(cpufreq_frequency_table_verify); */ int cpufreq_generic_frequency_table_verify(struct cpufreq_policy *policy) {

• struct cpufreq_frequency_table *table =

• cpufreq_frequency_get_table(policy->cpu);
  

• if (!table)

• if (!policy->freq_table) return -ENODEV;

• return cpufreq_frequency_table_verify(policy, table);

• return cpufreq_frequency_table_verify(policy, policy->freq_table);

} EXPORT_SYMBOL_GPL(cpufreq_generic_frequency_table_verify); @@ -210,9 +208,8 @@ EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target); int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy, unsigned int freq) {

• struct cpufreq_frequency_table *pos, *table;

• struct cpufreq_frequency_table *pos, *table = policy->freq_table;

• table = cpufreq_frequency_get_table(policy->cpu); if (unlikely(!table)) { pr_debug("%s: Unable to find frequency table\n", __func__); return -ENOENT;

diff --git a/drivers/cpufreq/ppc_cbe_cpufreq_pmi.c b/drivers/cpufreq/ppc_cbe_cpufreq_pmi.c index 7c4cd5c634f2..dc112481a408 100644 --- a/drivers/cpufreq/ppc_cbe_cpufreq_pmi.c +++ b/drivers/cpufreq/ppc_cbe_cpufreq_pmi.c @@ -94,7 +94,7 @@ static int pmi_notifier(struct notifier_block *nb, unsigned long event, void *data) { struct cpufreq_policy *policy = data;

• struct cpufreq_frequency_table *cbe_freqs;

• struct cpufreq_frequency_table *cbe_freqs = policy->freq_table; u8 node;

/* Should this really be called for CPUFREQ_ADJUST and CPUFREQ_NOTIFY @@ -103,7 +103,6 @@ static int pmi_notifier(struct notifier_block *nb, if (event == CPUFREQ_START) return 0;

• cbe_freqs = cpufreq_frequency_get_table(policy->cpu); node = cbe_cpu_to_node(policy->cpu);

pr_debug("got notified, event=%lu, node=%u\n", event, node); diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c index 6ceac4f2d4b2..63f760869651 100644 --- a/drivers/thermal/cpu_cooling.c +++ b/drivers/thermal/cpu_cooling.c @@ -787,6 +787,7 @@ __cpufreq_cooling_register(struct device_node *np, const struct cpumask *clip_cpus, u32 capacitance, get_static_t plat_static_func) {

• struct cpufreq_policy *policy; struct thermal_cooling_device *cool_dev; struct cpufreq_cooling_device *cpufreq_dev; char dev_name[THERMAL_NAME_LENGTH];

@@ -794,15 +795,24 @@ __cpufreq_cooling_register(struct device_node *np, unsigned int freq, i, num_cpus; int ret;

• table = cpufreq_frequency_get_table(cpumask_first(clip_cpus));

• policy = cpufreq_cpu_get(cpumask_first(clip_cpus));
• if (!policy) {

• pr_debug("%s: CPUFreq policy not found\n", __func__);
  

• return ERR_PTR(-EPROBE_DEFER);
  

• }
• table = policy->freq_table; if (!table) { pr_debug("%s: CPUFreq table not found\n", __func__);

• return ERR_PTR(-EPROBE_DEFER);
  

• cool_dev = ERR_PTR(-ENODEV);
  

• goto put_policy;
  

  }

cpufreq_dev = kzalloc(sizeof(*cpufreq_dev), GFP_KERNEL);

• if (!cpufreq_dev)

• return ERR_PTR(-ENOMEM);
  

• if (!cpufreq_dev) {

• cool_dev = ERR_PTR(-ENOMEM);
  

• goto put_policy;
  

• }

num_cpus = cpumask_weight(clip_cpus); cpufreq_dev->time_in_idle = kcalloc(num_cpus, @@ -892,7 +902,7 @@ __cpufreq_cooling_register(struct device_node *np, CPUFREQ_POLICY_NOTIFIER); mutex_unlock(&cooling_cpufreq_lock);

• return cool_dev;

• goto put_policy;

remove_idr: release_idr(&cpufreq_idr, cpufreq_dev->id); @@ -906,6 +916,8 @@ __cpufreq_cooling_register(struct device_node *np, kfree(cpufreq_dev->time_in_idle); free_cdev: kfree(cpufreq_dev); +put_policy:

• cpufreq_cpu_put(policy);

return cool_dev; } diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 7ed93c310c08..1342cbc0f25e 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -632,8 +632,6 @@ static inline bool policy_has_boost_freq(struct cpufreq_policy *policy) return false; } #endif -/* the following funtion is for cpufreq core use only */ -struct cpufreq_frequency_table *cpufreq_frequency_get_table(unsigned int cpu); /* the following are really really optional */ extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs; -- 2.7.1.410.g6faf27b