thermal: convert cpu_cooling to use an IDA

thermal cpu cooling does not use the ability to look up pointers by ID,
so convert it from using an IDR to the more space-efficient IDA.

The cooling_cpufreq_lock was being used to protect cpufreq_dev_count as
well as the IDR.  Rather than keep the mutex to protect a single integer,
I expanded the scope of cooling_list_lock to also cover cpufreq_dev_count.
We could also convert cpufreq_dev_count into an atomic.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 9ce0e9eef9230c725eb510692f47e794ece255e9..ea3cf7b5cb5b22be130fb50de55d6e73624c5fe4 100644 (file)
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -26,6 +26,7 @@
 #include <linux/thermal.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
+#include <linux/idr.h>
 #include <linux/pm_opp.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
@@ -104,50 +105,13 @@ struct cpufreq_cooling_device {
        struct device *cpu_dev;
        get_static_t plat_get_static_power;
 };
-static DEFINE_IDR(cpufreq_idr);
-static DEFINE_MUTEX(cooling_cpufreq_lock);
+static DEFINE_IDA(cpufreq_ida);
 
 static unsigned int cpufreq_dev_count;
 
 static DEFINE_MUTEX(cooling_list_lock);
 static LIST_HEAD(cpufreq_dev_list);
 
-/**
- * get_idr - function to get a unique id.
- * @idr: struct idr * handle used to create a id.
- * @id: int * value generated by this function.
- *
- * This function will populate @id with an unique
- * id, using the idr API.
- *
- * Return: 0 on success, an error code on failure.
- */
-static int get_idr(struct idr *idr, int *id)
-{
-       int ret;
-
-       mutex_lock(&cooling_cpufreq_lock);
-       ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
-       mutex_unlock(&cooling_cpufreq_lock);
-       if (unlikely(ret < 0))
-               return ret;
-       *id = ret;
-
-       return 0;
-}
-
-/**
- * release_idr - function to free the unique id.
- * @idr: struct idr * handle used for creating the id.
- * @id: int value representing the unique id.
- */
-static void release_idr(struct idr *idr, int id)
-{
-       mutex_lock(&cooling_cpufreq_lock);
-       idr_remove(idr, id);
-       mutex_unlock(&cooling_cpufreq_lock);
-}
-
 /* Below code defines functions to be used for cpufreq as cooling device */
 
 /**
@@ -874,11 +838,12 @@ __cpufreq_cooling_register(struct device_node *np,
                cooling_ops = &cpufreq_cooling_ops;
        }
 
-       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
-       if (ret) {
+       ret = ida_simple_get(&cpufreq_ida, 0, 0, GFP_KERNEL);
+       if (ret < 0) {
                cool_dev = ERR_PTR(ret);
                goto free_power_table;
        }
+       cpufreq_dev->id = ret;
 
        /* Fill freq-table in descending order of frequencies */
        for (i = 0, freq = -1; i <= cpufreq_dev->max_level; i++) {
@@ -898,27 +863,24 @@ __cpufreq_cooling_register(struct device_node *np,
        cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
                                                      cooling_ops);
        if (IS_ERR(cool_dev))
-               goto remove_idr;
+               goto remove_ida;
 
        cpufreq_dev->clipped_freq = cpufreq_dev->freq_table[0];
        cpufreq_dev->cool_dev = cool_dev;
 
-       mutex_lock(&cooling_cpufreq_lock);
-
        mutex_lock(&cooling_list_lock);
        list_add(&cpufreq_dev->node, &cpufreq_dev_list);
-       mutex_unlock(&cooling_list_lock);
 
        /* Register the notifier for first cpufreq cooling device */
        if (!cpufreq_dev_count++)
                cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
                                          CPUFREQ_POLICY_NOTIFIER);
-       mutex_unlock(&cooling_cpufreq_lock);
+       mutex_unlock(&cooling_list_lock);
 
        goto put_policy;
 
-remove_idr:
-       release_idr(&cpufreq_idr, cpufreq_dev->id);
+remove_ida:
+       ida_simple_remove(&cpufreq_ida, cpufreq_dev->id);
 free_power_table:
        kfree(cpufreq_dev->dyn_power_table);
 free_table:
@@ -1059,20 +1021,17 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 
        cpufreq_dev = cdev->devdata;
 
+       mutex_lock(&cooling_list_lock);
        /* Unregister the notifier for the last cpufreq cooling device */
-       mutex_lock(&cooling_cpufreq_lock);
        if (!--cpufreq_dev_count)
                cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
                                            CPUFREQ_POLICY_NOTIFIER);
 
-       mutex_lock(&cooling_list_lock);
        list_del(&cpufreq_dev->node);
        mutex_unlock(&cooling_list_lock);
 
-       mutex_unlock(&cooling_cpufreq_lock);
-
        thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
-       release_idr(&cpufreq_idr, cpufreq_dev->id);
+       ida_simple_remove(&cpufreq_ida, cpufreq_dev->id);
        kfree(cpufreq_dev->dyn_power_table);
        kfree(cpufreq_dev->time_in_idle_timestamp);
        kfree(cpufreq_dev->time_in_idle);