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thermal: cpu_cooling: don't call kcalloc() under rcu_read_lock
build_dyn_power_table() allocates the power table while holding
rcu_read_lock. kcalloc using GFP_KERNEL may sleep, so it can't be
called in an RCU read-side path.
Move the rcu protection to the part of the function that really needs
it: the part that handles the dev_pm_opp pointer received from
dev_pm_opp_find_freq_ceil(). In the unlikely case that there is an OPP
added to the cpu while this function is running, return -EAGAIN.
Fixes: c36cf07176
("thermal: cpu_cooling: implement the power cooling device API")
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
This commit is contained in:
parent
0847e26a84
commit
459ac37506
1 changed files with 23 additions and 24 deletions
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@ -262,7 +262,9 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
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* efficiently. Power is stored in mW, frequency in KHz. The
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* resulting table is in ascending order.
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*
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* Return: 0 on success, -E* on error.
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* Return: 0 on success, -EINVAL if there are no OPPs for any CPUs,
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* -ENOMEM if we run out of memory or -EAGAIN if an OPP was
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* added/enabled while the function was executing.
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*/
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static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
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u32 capacitance)
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@ -270,11 +272,9 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
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struct power_table *power_table;
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struct dev_pm_opp *opp;
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struct device *dev = NULL;
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int num_opps = 0, cpu, i, ret = 0;
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int num_opps = 0, cpu, i;
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unsigned long freq;
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rcu_read_lock();
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for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
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dev = get_cpu_device(cpu);
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if (!dev) {
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@ -284,24 +284,20 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
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}
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num_opps = dev_pm_opp_get_opp_count(dev);
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if (num_opps > 0) {
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if (num_opps > 0)
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break;
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} else if (num_opps < 0) {
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ret = num_opps;
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goto unlock;
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}
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else if (num_opps < 0)
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return num_opps;
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}
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if (num_opps == 0) {
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ret = -EINVAL;
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goto unlock;
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}
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if (num_opps == 0)
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return -EINVAL;
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power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
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if (!power_table) {
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ret = -ENOMEM;
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goto unlock;
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}
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if (!power_table)
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return -ENOMEM;
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rcu_read_lock();
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for (freq = 0, i = 0;
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opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
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@ -309,6 +305,11 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
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u32 freq_mhz, voltage_mv;
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u64 power;
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if (i >= num_opps) {
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rcu_read_unlock();
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return -EAGAIN;
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}
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freq_mhz = freq / 1000000;
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voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
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@ -326,18 +327,16 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
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power_table[i].power = power;
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}
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if (i == 0) {
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ret = PTR_ERR(opp);
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goto unlock;
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}
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rcu_read_unlock();
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if (i != num_opps)
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return PTR_ERR(opp);
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cpufreq_device->cpu_dev = dev;
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cpufreq_device->dyn_power_table = power_table;
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cpufreq_device->dyn_power_table_entries = i;
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unlock:
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rcu_read_unlock();
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return ret;
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return 0;
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}
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static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
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