On 24 June 2013 17:13, Rafael J. Wysocki rjw@sisk.pl wrote:
On Wednesday, June 19, 2013 02:23:07 PM Viresh Kumar wrote:
case CPUFREQ_POSTCHANGE:
WARN_ON(!transition_ongoing--);Shouldn't we try to avoid going into the negative range here?
What about this patch? Find it attached to apply.
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 2d53f47..6624694 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -107,6 +107,9 @@ static void handle_update(struct work_struct *work); static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list); static struct srcu_notifier_head cpufreq_transition_notifier_list;
+/* Tracks status of transition */ +static int transition_ongoing; + static bool init_cpufreq_transition_notifier_list_called; static int __init init_cpufreq_transition_notifier_list(void) { @@ -264,6 +267,13 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy, switch (state) {
case CPUFREQ_PRECHANGE: + if (transition_ongoing) { + WARN(1, "In middle of another frequency transition\n"); + return; + } + + transition_ongoing++; + /* detect if the driver reported a value as "old frequency" * which is not equal to what the cpufreq core thinks is * "old frequency". @@ -283,6 +293,13 @@ void __cpufreq_notify_transition(struct cpufreq_policy *policy, break;
case CPUFREQ_POSTCHANGE: + if (!transition_ongoing) { + WARN(1, "No frequency transition in progress\n"); + return; + } + + transition_ongoing--; + adjust_jiffies(CPUFREQ_POSTCHANGE, freqs); pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new, (unsigned long)freqs->cpu); @@ -1458,6 +1475,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
if (cpufreq_disabled()) return -ENODEV; + if (transition_ongoing) + return -EBUSY;
/* Make sure that target_freq is within supported range */ if (target_freq > policy->max)