X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=drivers%2Fcpufreq%2Fcpufreq_conservative.c;h=5ef5ede5b8848e96c3d7d4ba00d9e7e8a11bc60f;hb=3f5e573a08a369bd10d2f89b63a2d68843f64a6b;hp=037f6bf4543c3c29b98e6401d8cb242b85a2f993;hpb=95d465fd750897ab32462a6702fbfe1b122cbbc0;p=powerpc.git

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 037f6bf454..5ef5ede5b8 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -22,6 +22,7 @@
 #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>
@@ -58,7 +59,7 @@ static unsigned int 				def_sampling_rate;
 #define MAX_SAMPLING_DOWN_FACTOR		(10)
 #define TRANSITION_LATENCY_LIMIT		(10 * 1000)
 
-static void do_dbs_timer(void *data);
+static void do_dbs_timer(struct work_struct *work);
 
 struct cpu_dbs_info_s {
 	struct cpufreq_policy 	*cur_policy;
@@ -72,8 +73,16 @@ static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
 
 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);
+static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
 
 struct dbs_tuners {
 	unsigned int 		sampling_rate;
@@ -176,8 +185,7 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 	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;
 	}
@@ -196,8 +204,7 @@ static ssize_t store_down_threshold(struct cpufreq_policy *unused,
 	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;
 	}
@@ -413,20 +420,21 @@ static void dbs_check_cpu(int cpu)
 	}
 }
 
-static void do_dbs_timer(void *data)
+static void do_dbs_timer(struct work_struct *work)
 { 
 	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)
 {
-	INIT_WORK(&dbs_work, do_dbs_timer, NULL);
 	schedule_delayed_work(&dbs_work,
 			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 	return;