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-rw-r--r--kernel/sched/cpufreq.c48
1 files changed, 37 insertions, 11 deletions
diff --git a/kernel/sched/cpufreq.c b/kernel/sched/cpufreq.c
index 928c4ba32f68..1141954e73b4 100644
--- a/kernel/sched/cpufreq.c
+++ b/kernel/sched/cpufreq.c
@@ -14,24 +14,50 @@
DEFINE_PER_CPU(struct update_util_data *, cpufreq_update_util_data);
/**
- * cpufreq_set_update_util_data - Populate the CPU's update_util_data pointer.
+ * cpufreq_add_update_util_hook - Populate the CPU's update_util_data pointer.
* @cpu: The CPU to set the pointer for.
* @data: New pointer value.
+ * @func: Callback function to set for the CPU.
*
- * Set and publish the update_util_data pointer for the given CPU. That pointer
- * points to a struct update_util_data object containing a callback function
- * to call from cpufreq_update_util(). That function will be called from an RCU
- * read-side critical section, so it must not sleep.
+ * Set and publish the update_util_data pointer for the given CPU.
*
- * Callers must use RCU-sched callbacks to free any memory that might be
- * accessed via the old update_util_data pointer or invoke synchronize_sched()
- * right after this function to avoid use-after-free.
+ * The update_util_data pointer of @cpu is set to @data and the callback
+ * function pointer in the target struct update_util_data is set to @func.
+ * That function will be called by cpufreq_update_util() from RCU-sched
+ * read-side critical sections, so it must not sleep. @data will always be
+ * passed to it as the first argument which allows the function to get to the
+ * target update_util_data structure and its container.
+ *
+ * The update_util_data pointer of @cpu must be NULL when this function is
+ * called or it will WARN() and return with no effect.
*/
-void cpufreq_set_update_util_data(int cpu, struct update_util_data *data)
+void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
+ void (*func)(struct update_util_data *data, u64 time,
+ unsigned long util, unsigned long max))
{
- if (WARN_ON(data && !data->func))
+ if (WARN_ON(!data || !func))
return;
+ if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu)))
+ return;
+
+ data->func = func;
rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), data);
}
-EXPORT_SYMBOL_GPL(cpufreq_set_update_util_data);
+EXPORT_SYMBOL_GPL(cpufreq_add_update_util_hook);
+
+/**
+ * cpufreq_remove_update_util_hook - Clear the CPU's update_util_data pointer.
+ * @cpu: The CPU to clear the pointer for.
+ *
+ * Clear the update_util_data pointer for the given CPU.
+ *
+ * Callers must use RCU-sched callbacks to free any memory that might be
+ * accessed via the old update_util_data pointer or invoke synchronize_sched()
+ * right after this function to avoid use-after-free.
+ */
+void cpufreq_remove_update_util_hook(int cpu)
+{
+ rcu_assign_pointer(per_cpu(cpufreq_update_util_data, cpu), NULL);
+}
+EXPORT_SYMBOL_GPL(cpufreq_remove_update_util_hook);