The patch titled
x86_64: Move ondemand timer into own work queue
has been removed from the -mm tree. Its filename is
x86_64-move-ondemand-timer-into-own-work-queue.patch
This patch was probably dropped from -mm because
it has now been merged into a subsystem tree or
into Linus's tree, or because it was folded into
its parent patch in the -mm tree.
From: Andi Kleen <ak@xxxxxxx>
Taking the cpu hotplug semaphore in a normal events workqueue is unsafe
because other tasks can wait for any workqueues with it hold. This results in
a deadlock.
Move the DBS timer into its own work queue which is not affected by other work
queue flushes to avoid this.
Cc: <venkatesh.pallipadi@xxxxxxxxx>
Cc: <cpufreq@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxx>
Acked-by: Dave Jones <davej@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/cpufreq/cpufreq_ondemand.c | 28 +++++++++++++++++++--------
1 files changed, 20 insertions(+), 8 deletions(-)
diff -puN drivers/cpufreq/cpufreq_ondemand.c~x86_64-move-ondemand-timer-into-own-work-queue drivers/cpufreq/cpufreq_ondemand.c
--- devel/drivers/cpufreq/cpufreq_ondemand.c~x86_64-move-ondemand-timer-into-own-work-queue 2006-05-10 21:18:15.000000000 -0700
+++ devel-akpm/drivers/cpufreq/cpufreq_ondemand.c 2006-05-10 21:18:15.000000000 -0700
@@ -74,6 +74,8 @@ static unsigned int dbs_enable; /* numbe
static DEFINE_MUTEX (dbs_mutex);
static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
+static struct workqueue_struct *dbs_workq;
+
struct dbs_tuners {
unsigned int sampling_rate;
unsigned int sampling_down_factor;
@@ -364,23 +366,29 @@ static void do_dbs_timer(void *data)
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));
+ queue_delayed_work(dbs_workq, &dbs_work,
+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
mutex_unlock(&dbs_mutex);
}
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));
+ if (!dbs_workq)
+ dbs_workq = create_singlethread_workqueue("ondemand");
+ if (!dbs_workq) {
+ printk(KERN_ERR "ondemand: Cannot initialize kernel thread\n");
+ return;
+ }
+ queue_delayed_work(dbs_workq, &dbs_work,
+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
return;
}
static inline void dbs_timer_exit(void)
{
- cancel_delayed_work(&dbs_work);
- return;
+ if (dbs_workq)
+ cancel_rearming_delayed_workqueue(dbs_workq, &dbs_work);
}
static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
@@ -489,8 +497,12 @@ static int __init cpufreq_gov_dbs_init(v
static void __exit cpufreq_gov_dbs_exit(void)
{
- /* Make sure that the scheduled work is indeed not running */
- flush_scheduled_work();
+ /* Make sure that the scheduled work is indeed not running.
+ Assumes the timer has been cancelled first. */
+ if (dbs_workq) {
+ flush_workqueue(dbs_workq);
+ destroy_workqueue(dbs_workq);
+ }
cpufreq_unregister_governor(&cpufreq_gov_dbs);
}
_
Patches currently in -mm which might be from ak@xxxxxxx are
origin.patch
x86_64-disable-aperture-pci-region-check-in-amd64.patch
x86_64-check-for-too-many-northbridges-in-iommu.patch
git-acpi.patch
git-agpgart.patch
x86_64-mm-serialize-assign_irq_vector-use-of-static-variables-fix.patch
-
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