[PATCH] thermal: use cpumask_var_t for on-stack cpu masks

[Arnd Bergmann]

Putting a bare cpumask structure on the stack produces a warning on
large SMP configurations:

drivers/thermal/cpu_cooling.c: In function 'cpufreq_state2power':
drivers/thermal/cpu_cooling.c:644:1: warning: the frame size of 1056 bytes is 
larger than 1024 bytes [-Wframe-larger-than=]
drivers/thermal/cpu_cooling.c: In function '__cpufreq_cooling_register':
drivers/thermal/cpu_cooling.c:898:1: warning: the frame size of 1104 bytes is 
larger than 1024 bytes [-Wframe-larger-than=]

The recommended workaround is to use cpumask_var_t, which behaves just like
a normal cpu mask in most cases, but turns into a dynamic allocation
when CONFIG_CPUMASK_OFFSTACK is set.

Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
 drivers/thermal/cpu_cooling.c | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index ca7ddaea450c..1d7f7e85f669 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -609,31 +609,39 @@ static int cpufreq_state2power(struct 
thermal_cooling_device *cdev,
                               unsigned long state, u32 *power)
 {
        unsigned int freq, num_cpus;
-       cpumask_t cpumask;
+       cpumask_var_t cpumask;
        u32 static_power, dynamic_power;
        int ret;
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 
-       cpumask_and(&cpumask, &cpufreq_device->allowed_cpus, cpu_online_mask);
-       num_cpus = cpumask_weight(&cpumask);
+       if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
+               return -ENOMEM;
+
+       cpumask_and(cpumask, &cpufreq_device->allowed_cpus, cpu_online_mask);
+       num_cpus = cpumask_weight(cpumask);
 
        /* None of our cpus are online, so no power */
        if (num_cpus == 0) {
                *power = 0;
-               return 0;
+               ret = 0;
+               goto out;
        }
 
        freq = cpufreq_device->freq_table[state];
-       if (!freq)
-               return -EINVAL;
+       if (!freq) {
+               ret = -EINVAL;
+               goto out;
+       }
 
        dynamic_power = cpu_freq_to_power(cpufreq_device, freq) * num_cpus;
        ret = get_static_power(cpufreq_device, tz, freq, &static_power);
        if (ret)
-               return ret;
+               goto out;
 
        *power = static_power + dynamic_power;
-       return 0;
+out:
+       free_cpumask_var(cpumask);
+       return ret;;
 }
 
 /**
@@ -759,16 +767,20 @@ __cpufreq_cooling_register(struct device_node *np,
        struct cpufreq_cooling_device *cpufreq_dev;
        char dev_name[THERMAL_NAME_LENGTH];
        struct cpufreq_frequency_table *pos, *table;
-       struct cpumask temp_mask;
+       cpumask_var_t temp_mask;
        unsigned int freq, i, num_cpus;
        int ret;
        struct thermal_cooling_device_ops *cooling_ops;
 
-       cpumask_and(&temp_mask, clip_cpus, cpu_online_mask);
-       policy = cpufreq_cpu_get(cpumask_first(&temp_mask));
+       if (!alloc_cpumask_var(&temp_mask, GFP_KERNEL))
+               return ERR_PTR(-ENOMEM);
+
+       cpumask_and(temp_mask, clip_cpus, cpu_online_mask);
+       policy = cpufreq_cpu_get(cpumask_first(temp_mask));
        if (!policy) {
                pr_debug("%s: CPUFreq policy not found\n", __func__);
-               return ERR_PTR(-EPROBE_DEFER);
+               cool_dev = ERR_PTR(-EPROBE_DEFER);
+               goto free_cpumask;
        }
 
        table = policy->freq_table;
@@ -886,7 +898,8 @@ __cpufreq_cooling_register(struct device_node *np,
        kfree(cpufreq_dev);
 put_policy:
        cpufreq_cpu_put(policy);
-
+free_cpumask:
+       free_cpumask_var(temp_mask);
        return cool_dev;
 }
 
-- 
2.9.0