#include <linux/types.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
+#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/workqueue.h>
static unsigned int dbs_enable; /* number of CPUs using this policy */
+/*
+ * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
+ * lock and dbs_mutex. cpu_hotplug lock should always be held before
+ * dbs_mutex. If any function that can potentially take cpu_hotplug lock
+ * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
+ * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
+ * is recursive for the same process. -Venki
+ */
static DEFINE_MUTEX (dbs_mutex);
static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
ret = sscanf (buf, "%u", &input);
mutex_lock(&dbs_mutex);
- if (ret != 1 || input > 100 || input < 0 ||
- input <= dbs_tuners_ins.down_threshold) {
+ if (ret != 1 || input > 100 || input <= dbs_tuners_ins.down_threshold) {
mutex_unlock(&dbs_mutex);
return -EINVAL;
}
ret = sscanf (buf, "%u", &input);
mutex_lock(&dbs_mutex);
- if (ret != 1 || input > 100 || input < 0 ||
- input >= dbs_tuners_ins.up_threshold) {
+ if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
mutex_unlock(&dbs_mutex);
return -EINVAL;
}
static void do_dbs_timer(void *data)
{
int i;
+ lock_cpu_hotplug();
mutex_lock(&dbs_mutex);
for_each_online_cpu(i)
dbs_check_cpu(i);
schedule_delayed_work(&dbs_work,
usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
mutex_unlock(&dbs_mutex);
+ unlock_cpu_hotplug();
}
static inline void dbs_timer_init(void)