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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:
Javi Merino 2015-08-17 19:21:42 +01:00 committed by Eduardo Valentin
parent 0847e26a84
commit 459ac37506
1 changed files with 23 additions and 24 deletions
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47
drivers/thermal/cpu_cooling.c
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@ -262,7 +262,9 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
* efficiently. Power is stored in mW, frequency in KHz. The
* resulting table is in ascending order.
*
* Return: 0 on success, -E* on error.
* Return: 0 on success, -EINVAL if there are no OPPs for any CPUs,
* -ENOMEM if we run out of memory or -EAGAIN if an OPP was
* added/enabled while the function was executing.
*/
static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
u32 capacitance)
@ -270,11 +272,9 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
struct power_table *power_table;
struct dev_pm_opp *opp;
struct device *dev = NULL;
int num_opps = 0, cpu, i, ret = 0;
int num_opps = 0, cpu, i;
unsigned long freq;
rcu_read_lock();
for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
dev = get_cpu_device(cpu);
if (!dev) {
@ -284,24 +284,20 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
}
num_opps = dev_pm_opp_get_opp_count(dev);
if (num_opps > 0) {
if (num_opps > 0)
break;
} else if (num_opps < 0) {
ret = num_opps;
goto unlock;
}
else if (num_opps < 0)
return num_opps;
}
if (num_opps == 0) {
ret = -EINVAL;
goto unlock;
}
if (num_opps == 0)
return -EINVAL;
power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
if (!power_table) {
ret = -ENOMEM;
goto unlock;
}
if (!power_table)
return -ENOMEM;
rcu_read_lock();
for (freq = 0, i = 0;
opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
@ -309,6 +305,11 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
u32 freq_mhz, voltage_mv;
u64 power;
if (i >= num_opps) {
rcu_read_unlock();
return -EAGAIN;
}
freq_mhz = freq / 1000000;
voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
@ -326,18 +327,16 @@ static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
power_table[i].power = power;
}
if (i == 0) {
ret = PTR_ERR(opp);
goto unlock;
}
rcu_read_unlock();
if (i != num_opps)
return PTR_ERR(opp);
cpufreq_device->cpu_dev = dev;
cpufreq_device->dyn_power_table = power_table;
cpufreq_device->dyn_power_table_entries = i;
unlock:
rcu_read_unlock();
return ret;
return 0;
}
static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,