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From:   "Rafael J. Wysocki" <rjw@rjwysocki.net>
To:     Linux PM <linux-pm@vger.kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>
Subject: [PATCH v1] thermal: core: Clean up thermal_list_lock locking
Date:   Wed, 22 Mar 2023 20:34:12 +0100
Message-ID: <2696911.mvXUDI8C0e@kreacher>
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Precedence: bulk

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Once thermal_list_lock has been acquired in
__thermal_cooling_device_register(), it is not necessary to drop it
and take it again until all of the thermal zones have been updated,
so change the code accordingly.

No expected functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/thermal/thermal_core.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -826,8 +826,6 @@ static void bind_cdev(struct thermal_coo
 	const struct thermal_zone_params *tzp;
 	struct thermal_zone_device *pos = NULL;
 
-	mutex_lock(&thermal_list_lock);
-
 	list_for_each_entry(pos, &thermal_tz_list, node) {
 		if (!pos->tzp && !pos->ops->bind)
 			continue;
@@ -854,8 +852,6 @@ static void bind_cdev(struct thermal_coo
 			       tzp->tbp[i].weight);
 		}
 	}
-
-	mutex_unlock(&thermal_list_lock);
 }
 
 /**
@@ -933,17 +929,17 @@ __thermal_cooling_device_register(struct
 
 	/* Add 'this' new cdev to the global cdev list */
 	mutex_lock(&thermal_list_lock);
+
 	list_add(&cdev->node, &thermal_cdev_list);
-	mutex_unlock(&thermal_list_lock);
 
 	/* Update binding information for 'this' new cdev */
 	bind_cdev(cdev);
 
-	mutex_lock(&thermal_list_lock);
 	list_for_each_entry(pos, &thermal_tz_list, node)
 		if (atomic_cmpxchg(&pos->need_update, 1, 0))
 			thermal_zone_device_update(pos,
 						   THERMAL_EVENT_UNSPECIFIED);
+
 	mutex_unlock(&thermal_list_lock);
 
 	return cdev;