Re: [PATCH 5/7] cpufreq: balance out cpufreq_cpu_{get,put} for scalingdrivers using setpolicy
From: Dirk Brandewie
Date: Wed Feb 06 2013 - 11:11:18 EST
On 02/05/2013 06:45 PM, Viresh Kumar wrote:
On 6 February 2013 07:38, Dirk Brandewie <dirk.brandewie@xxxxxxxxx> wrote:
On 02/05/2013 05:58 PM, Viresh Kumar wrote:
On Tue, Feb 5, 2013 at 11:54 PM, <dirk.brandewie@xxxxxxxxx> wrote:
From: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>
There is an additional reference added to the driver in
cpufreq_add_dev() that is removed in__cpufreq_governor() if the
driver implements target(). Remove the last reference when the
driver implements setpolicy()
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
---
drivers/cpufreq/cpufreq.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 622e282..d17477b 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1049,6 +1049,9 @@ static int __cpufreq_remove_dev(struct device *dev,
struct subsys_interface *sif
if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
+ if (cpufreq_driver->setpolicy)
+ cpufreq_cpu_put(data);
I don't understand this patch at all.. I grepped both cpufreq_cpu_get() &
put()
in bleeding-edge and found everything to be correct.
Can you please point me to the exact line numbers ?
Line 878 in cpufreq_add_dev()
Following is line 878:
for_each_online_cpu(sibling) {
struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
if (cp && cpumask_test_cpu(cpu, cp->related_cpus))
return cpufreq_add_policy_cpu(cpu, sibling, dev);
}
How is this related to your patch?
our files are clearly out of sync :-) The code in cpufreq_add_dev() is
#ifdef CONFIG_SMP
/* check whether a different CPU already registered this
* CPU because it is in the same boat. */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
cpufreq_cpu_put(policy);
return 0;
}
The reference added by this cpufreq_cpu_get() is finally dropped in
__cpufreq_remove_dev() with the call to __cpufreq_governor()
if (driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
Without this change I hang at:
pr_debug("waiting for dropping of refcount\n");
wait_for_completion(cmp);
--Dirk
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