linux-kernel - [PATCH 60/70] cpufreq: interactive: hold reference on global cpufreq kobject if needed

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Date:	Tue, 27 Oct 2015 18:30:48 +0100
From:	Bálint Czobor <czoborbalint@...il.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Greg Hackmann <ghackmann@...gle.com>,
	Bálint Czobor <czoborbalint@...il.com>
Subject: [PATCH 60/70] cpufreq: interactive: hold reference on global cpufreq kobject if needed

From: Greg Hackmann <ghackmann@...gle.com>

2361be23666232dbb4851a527f466c4cbf5340fc changed cpufreq to add the
global cpufreq kobject to sysfs on demand.

To ensure this happens, cpufreq_interactive must hold a reference on
this object on devices where it intends to use it (i.e., devices where
have_governor_per_policy() returns false).  Otherwise a parentless
kobject will be passed to sysfs_create_group() which will subsequently
BUG().

Change-Id: I7dd03956e1d3c6c3c0cc17c799882c235804ae09
Signed-off-by: Greg Hackmann <ghackmann@...gle.com>
Signed-off-by: Bálint Czobor <czoborbalint@...il.com>
---
 drivers/cpufreq/cpufreq_interactive.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index ff77b30..786fd01 100644
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -1154,8 +1154,10 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 		spin_lock_init(&tunables->above_hispeed_delay_lock);
 
 		policy->governor_data = tunables;
-		if (!have_governor_per_policy())
+		if (!have_governor_per_policy()) {
 			common_tunables = tunables;
+			WARN_ON(cpufreq_get_global_kobject());
+		}
 
 		rc = sysfs_create_group(get_governor_parent_kobj(policy),
 				get_sysfs_attr());
@@ -1185,6 +1187,10 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 
 			sysfs_remove_group(get_governor_parent_kobj(policy),
 					get_sysfs_attr());
+
+			if (!have_governor_per_policy())
+				cpufreq_put_global_kobject();
+
 			kfree(tunables);
 			common_tunables = NULL;
 		}
-- 
1.7.9.5

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