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| author | Andi Kleen <ak@suse.de> | 2006-05-08 15:17:31 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-08 09:34:56 -0700 |
| commit | 6810b548b25114607e0814612d84125abccc0a4f (patch) | |
| tree | 51dab8f9b809479b038e2d957e74fba7e1e99e49 /drivers/cpufreq | |
| parent | ac71d12c990526b01ef6cfe50907ef8530a30331 (diff) | |
| download | linux-6810b548b25114607e0814612d84125abccc0a4f.tar.gz linux-6810b548b25114607e0814612d84125abccc0a4f.tar.bz2 linux-6810b548b25114607e0814612d84125abccc0a4f.zip | |
[PATCH] x86_64: Move ondemand timer into own work queue
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.
Has been acked by Venkatesh.
Cc: venkatesh.pallipadi@intel.com
Cc: cpufreq@lists.linux.org.uk
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/cpufreq')
| -rw-r--r-- | drivers/cpufreq/cpufreq_ondemand.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c index 956d121cb161..3e6ffcaa5af4 100644 --- a/drivers/cpufreq/cpufreq_ondemand.c +++ b/drivers/cpufreq/cpufreq_ondemand.c @@ -74,6 +74,8 @@ static unsigned int dbs_enable; /* number of CPUs using this policy */ 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(void) 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); } |