diff options
| author | Viresh Kumar <viresh.kumar@linaro.org> | 2013-06-19 10:16:55 +0530 |
|---|---|---|
| committer | Marek Szyprowski <m.szyprowski@samsung.com> | 2014-04-01 13:07:34 +0200 |
| commit | f561427a7dbfd94e20b69e062d4b1c0ffc93d996 (patch) | |
| tree | 57af5fe47f018eac38f33780a5267021b59682b9 | |
| parent | f51c2fdcf1b44b319191c1876300e59bf58625ba (diff) | |
| download | linux-3.10-f561427a7dbfd94e20b69e062d4b1c0ffc93d996.tar.gz linux-3.10-f561427a7dbfd94e20b69e062d4b1c0ffc93d996.tar.bz2 linux-3.10-f561427a7dbfd94e20b69e062d4b1c0ffc93d996.zip | |
cpufreq: make sure frequency transitions are serialized
Whenever we are changing frequency of a cpu, we are calling PRECHANGE and
POSTCHANGE notifiers. They must be serialized. i.e. PRECHANGE or POSTCHANGE
shouldn't be called twice contiguously.
This can happen due to bugs in users of __cpufreq_driver_target() or actual
cpufreq drivers who are sending these notifiers.
This patch adds some protection against this. Now, we keep track of the last
transaction and see if something went wrong.
Change-Id: I0f5465bd515c431ae2d3711d065f70aacec7e978
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 14 | ||||
| -rw-r--r-- | include/linux/cpufreq.h | 1 |
2 files changed, 15 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 704d5ecb79d..00050b057cb 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -266,6 +266,12 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy, switch (state) { case CPUFREQ_PRECHANGE: + if (WARN(policy->transition_ongoing, + "In middle of another frequency transition\n")) + return; + + policy->transition_ongoing = true; + /* detect if the driver reported a value as "old frequency" * which is not equal to what the cpufreq core thinks is * "old frequency". @@ -285,6 +291,12 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy, break; case CPUFREQ_POSTCHANGE: + if (WARN(!policy->transition_ongoing, + "No frequency transition in progress\n")) + return; + + policy->transition_ongoing = false; + adjust_jiffies(CPUFREQ_POSTCHANGE, freqs); pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new, (unsigned long)freqs->cpu); @@ -1529,6 +1541,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy, if (cpufreq_disabled()) return -ENODEV; + if (policy->transition_ongoing) + return -EBUSY; /* Make sure that target_freq is within supported range */ if (target_freq > policy->max) diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 9791c329c3e..e3da73bbcf0 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -121,6 +121,7 @@ struct cpufreq_policy { struct list_head policy_list; struct kobject kobj; struct completion kobj_unregister; + bool transition_ongoing; /* Tracks transition status */ }; #define CPUFREQ_ADJUST (0) |