Userspace is free to read value of any file from cpufreq/stats directory once they are created. __cpufreq_stats_create_table() is creating the sysfs files first and then allocating resources for them. Though it would be quite difficult to trigger the racy situation here, but for the sake of keeping sensible code lets create sysfs entries only after we are ready to go.
This also does some makeup to the routine to make it look better.
Reviewed-by: Prarit Bhargava prarit@redhat.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- drivers/cpufreq/cpufreq_stats.c | 44 +++++++++++++++++++++++------------------ 1 file changed, 25 insertions(+), 19 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c index 1ed703a3e21e..17df8c507594 100644 --- a/drivers/cpufreq/cpufreq_stats.c +++ b/drivers/cpufreq/cpufreq_stats.c @@ -164,12 +164,13 @@ static void cpufreq_stats_free_table(unsigned int cpu)
static int __cpufreq_stats_create_table(struct cpufreq_policy *policy) { - unsigned int i, count = 0, ret = 0; + 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); if (unlikely(!table)) return 0; @@ -179,15 +180,10 @@ static int __cpufreq_stats_create_table(struct cpufreq_policy *policy) return -EEXIST;
stats = kzalloc(sizeof(*stats), GFP_KERNEL); - if ((stats) == NULL) + if (!stats) return -ENOMEM;
- ret = sysfs_create_group(&policy->kobj, &stats_attr_group); - if (ret) - goto error_out; - - policy->stats = stats; - + /* Find total allocation size */ cpufreq_for_each_valid_entry(pos, table) count++;
@@ -196,32 +192,42 @@ static int __cpufreq_stats_create_table(struct cpufreq_policy *policy) #ifdef CONFIG_CPU_FREQ_STAT_DETAILS alloc_size += count * count * sizeof(int); #endif - stats->max_state = count; + + /* Allocate memory for time_in_state/freq_table/trans_table in one go */ stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL); - if (!stats->time_in_state) { - ret = -ENOMEM; - goto error_alloc; - } + if (!stats->time_in_state) + goto free_stat; + stats->freq_table = (unsigned int *)(stats->time_in_state + count);
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS stats->trans_table = stats->freq_table + count; #endif - i = 0; + + stats->max_state = count; + + /* Find valid-unique entries */ cpufreq_for_each_valid_entry(pos, table) if (freq_table_get_index(stats, pos->frequency) == -1) stats->freq_table[i++] = pos->frequency; stats->state_num = i; + spin_lock(&cpufreq_stats_lock); stats->last_time = get_jiffies_64(); stats->last_index = freq_table_get_index(stats, policy->cur); spin_unlock(&cpufreq_stats_lock); - return 0; -error_alloc: - sysfs_remove_group(&policy->kobj, &stats_attr_group); -error_out: - kfree(stats); + + policy->stats = stats; + ret = sysfs_create_group(&policy->kobj, &stats_attr_group); + if (!ret) + return 0; + + /* We failed, release resources */ policy->stats = NULL; + kfree(stats->time_in_state); +free_stat: + kfree(stats); + return ret; }