linux-kernel - [PATCH 1/3] opp: Always add entries in dev_list with opp

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Message-Id: <ef43f01ac06976b2aa2b17266d307bb1a4f7e6f9.1604294460.git.viresh.kumar@linaro.org>
Date:   Mon,  2 Nov 2020 10:51:38 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>, robdclark@...il.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] opp: Always add entries in dev_list with opp_table->lock held

The readers of dev_list expect the updates to it to take place from
within the opp_table->lock and this is missing in the case where the
dev_list is updated for already managed OPPs.

Fix that by calling _add_opp_dev() from there and remove the now unused
_add_opp_dev_unlocked() callback. While at it, also reduce the length of
the critical section in _add_opp_dev().

Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/opp/core.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 0e0a5269dc82..84035ab8bb31 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1036,8 +1036,8 @@ static void _remove_opp_dev(struct opp_device *opp_dev,
 	kfree(opp_dev);
 }
 
-static struct opp_device *_add_opp_dev_unlocked(const struct device *dev,
-						struct opp_table *opp_table)
+struct opp_device *_add_opp_dev(const struct device *dev,
+				struct opp_table *opp_table)
 {
 	struct opp_device *opp_dev;
 
@@ -1048,7 +1048,9 @@ static struct opp_device *_add_opp_dev_unlocked(const struct device *dev,
 	/* Initialize opp-dev */
 	opp_dev->dev = dev;
 
+	mutex_lock(&opp_table->lock);
 	list_add(&opp_dev->node, &opp_table->dev_list);
+	mutex_unlock(&opp_table->lock);
 
 	/* Create debugfs entries for the opp_table */
 	opp_debug_register(opp_dev, opp_table);
@@ -1056,18 +1058,6 @@ static struct opp_device *_add_opp_dev_unlocked(const struct device *dev,
 	return opp_dev;
 }
 
-struct opp_device *_add_opp_dev(const struct device *dev,
-				struct opp_table *opp_table)
-{
-	struct opp_device *opp_dev;
-
-	mutex_lock(&opp_table->lock);
-	opp_dev = _add_opp_dev_unlocked(dev, opp_table);
-	mutex_unlock(&opp_table->lock);
-
-	return opp_dev;
-}
-
 static struct opp_table *_allocate_opp_table(struct device *dev, int index)
 {
 	struct opp_table *opp_table;
@@ -1148,7 +1138,7 @@ static struct opp_table *_opp_get_opp_table(struct device *dev, int index)
 
 	opp_table = _managed_opp(dev, index);
 	if (opp_table) {
-		if (!_add_opp_dev_unlocked(dev, opp_table)) {
+		if (!_add_opp_dev(dev, opp_table)) {
 			dev_pm_opp_put_opp_table(opp_table);
 			opp_table = ERR_PTR(-ENOMEM);
 		}
-- 
2.25.0.rc1.19.g042ed3e048af