From: Henry Willard <henry.willard@oracle.com>
To: <rjw@rjwysocki.net>, <viresh.kumar@linaro.org>
Cc: <linux-pm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<henry.willard@oracle.com>
Subject: [PATCH] cpufreq: governor: Protect cpufreq governor_data
Date: Tue, 14 Aug 2018 17:01:02 -0700 [thread overview]
Message-ID: <1534291262-4207-1-git-send-email-henry.willard@oracle.com> (raw)
If cppc_cpufreq.ko is deleted at the same time that tuned-adm is
changing profiles, there is a small chance that a race can occur
between cpufreq_dbs_governor_exit() and cpufreq_dbs_governor_limits()
resulting in a system failure when the latter tries to use
policy->governor_data that has been freed by the former.
This patch uses gov_dbs_data_mutex to synchronize access.
Signed-off-by: Henry Willard <henry.willard@oracle.com>
---
drivers/cpufreq/cpufreq_governor.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 1d50e97d49f1..43416ee55849 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -555,12 +555,20 @@ void cpufreq_dbs_governor_stop(struct cpufreq_policy *policy)
void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)
{
- struct policy_dbs_info *policy_dbs = policy->governor_data;
+ struct policy_dbs_info *policy_dbs;
+
+ /* Protect gov->gdbs_data against cpufreq_dbs_governor_exit */
+ mutex_lock(&gov_dbs_data_mutex);
+ policy_dbs = policy->governor_data;
+ if (!policy_dbs)
+ goto out;
mutex_lock(&policy_dbs->update_mutex);
cpufreq_policy_apply_limits(policy);
gov_update_sample_delay(policy_dbs, 0);
mutex_unlock(&policy_dbs->update_mutex);
+out:
+ mutex_unlock(&gov_dbs_data_mutex);
}
EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_limits);
--
1.8.3.1
next reply other threads:[~2018-08-15 0:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-15 0:01 Henry Willard [this message]
2018-08-20 9:07 ` [PATCH] cpufreq: governor: Protect cpufreq governor_data Rafael J. Wysocki
2018-09-13 14:29 ` Jeremy Cline
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1534291262-4207-1-git-send-email-henry.willard@oracle.com \
--to=henry.willard@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rjw@rjwysocki.net \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).