From: Viresh Kumar <viresh.kumar@linaro.org>
To: Rafael Wysocki <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
linux-pm@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH 2/2] cpufreq: stats: Fix concurrency issues while resetting stats
Date: Fri, 1 Feb 2019 11:45:45 +0530 [thread overview]
Message-ID: <927dcc1de6acad3dd2cfae4e300e6fee4f665101.1549001732.git.viresh.kumar@linaro.org> (raw)
In-Reply-To: <d5d8c15aca712342350d2f451002f55e15e9e93b.1549001732.git.viresh.kumar@linaro.org>
It is possible for cpufreq_stats_clear_table() and
cpufreq_stats_record_transition() to get called concurrently and they
will try to update same variables simultaneously and may lead to
corruption of data.
Prevent that with the help of existing spinlock.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/cpufreq/cpufreq_stats.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 941e63e3e652..e2db5581489a 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -31,20 +31,20 @@ static void cpufreq_stats_update(struct cpufreq_stats *stats)
{
unsigned long long cur_time = get_jiffies_64();
- spin_lock(&cpufreq_stats_lock);
stats->time_in_state[stats->last_index] += cur_time - stats->last_time;
stats->last_time = cur_time;
- spin_unlock(&cpufreq_stats_lock);
}
static void cpufreq_stats_clear_table(struct cpufreq_stats *stats)
{
unsigned int count = stats->max_state;
+ spin_lock(&cpufreq_stats_lock);
memset(stats->time_in_state, 0, count * sizeof(u64));
memset(stats->trans_table, 0, count * count * sizeof(int));
stats->last_time = get_jiffies_64();
stats->total_trans = 0;
+ spin_unlock(&cpufreq_stats_lock);
}
static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
@@ -62,7 +62,10 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
if (policy->fast_switch_enabled)
return 0;
+ spin_lock(&cpufreq_stats_lock);
cpufreq_stats_update(stats);
+ spin_unlock(&cpufreq_stats_lock);
+
for (i = 0; i < stats->state_num; i++) {
len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
(unsigned long long)
@@ -239,9 +242,11 @@ void cpufreq_stats_record_transition(struct cpufreq_policy *policy,
if (old_index == -1 || new_index == -1 || old_index == new_index)
return;
+ spin_lock(&cpufreq_stats_lock);
cpufreq_stats_update(stats);
stats->last_index = new_index;
stats->trans_table[old_index * stats->max_state + new_index]++;
stats->total_trans++;
+ spin_unlock(&cpufreq_stats_lock);
}
--
2.20.1.321.g9e740568ce00
next prev parent reply other threads:[~2019-02-01 6:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-01 6:15 [PATCH 1/2] cpufreq: stats: Declare freq-attr right after their callbacks Viresh Kumar
2019-02-01 6:15 ` Viresh Kumar [this message]
2019-02-04 22:31 ` [PATCH 2/2] cpufreq: stats: Fix concurrency issues while resetting stats Matthias Kaehlcke
2019-02-06 10:29 ` [PATCH 1/2] cpufreq: stats: Declare freq-attr right after their callbacks Rafael J. Wysocki
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