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authorJavi Merino <javi.merino@arm.com>2015-08-17 19:21:42 +0100
committerEduardo Valentin <edubezval@gmail.com>2015-09-13 20:33:17 -0700
commit459ac37506d195713b5e82271a2ac44a777e47df (patch)
tree7a3071c20fcaa2b5d11b452b1969359ac722b5e6
parent0847e26a84faa0fcb4572d7e42d0a44cab69a83d (diff)
downloadop-kernel-dev-459ac37506d195713b5e82271a2ac44a777e47df.zip
op-kernel-dev-459ac37506d195713b5e82271a2ac44a777e47df.tar.gz
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: c36cf0717631 ("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>
-rw-r--r--drivers/thermal/cpu_cooling.c47
1 files changed, 23 insertions, 24 deletions
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 620dcd4..b327556 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -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,
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