linux-kernel - [PATCH v1 02/17] thermal: core: Rearrange checks in thermal_bind_cdev_to

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Message-ID: <15273675.JCcGWNJJiE@rjwysocki.net>
Date: Tue, 30 Jul 2024 20:45:22 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Linux ACPI <linux-acpi@...r.kernel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Lukasz Luba <lukasz.luba@....com>, Zhang Rui <rui.zhang@...el.com>
Subject:
 [PATCH v1 02/17] thermal: core: Rearrange checks in
 thermal_bind_cdev_to_trip()

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

It is not necessary to look up the thermal zone and the cooling device
in the respective global lists to check whether or not they are
registered.  It is sufficient to check whether or not their respective
list nodes are empty for this purpose.

Use the above observation to simplify thermal_bind_cdev_to_trip().  In
addition, eliminate an unnecessary ternary operator from it.

Moreover, add lockdep_assert_held() for thermal_list_lock to it because
that lock must be held by its callers when it is running.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/thermal/thermal_core.c |   16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -781,25 +781,17 @@ int thermal_bind_cdev_to_trip(struct the
 {
 	struct thermal_instance *dev;
 	struct thermal_instance *pos;
-	struct thermal_zone_device *pos1;
-	struct thermal_cooling_device *pos2;
 	bool upper_no_limit;
 	int result;

-	list_for_each_entry(pos1, &thermal_tz_list, node) {
-		if (pos1 == tz)
-			break;
-	}
-	list_for_each_entry(pos2, &thermal_cdev_list, node) {
-		if (pos2 == cdev)
-			break;
-	}
+	lockdep_assert_held(&thermal_list_lock);

-	if (tz != pos1 || cdev != pos2)
+	if (list_empty(&tz->node) || list_empty(&cdev->node))
 		return -EINVAL;

 	/* lower default 0, upper default max_state */
-	lower = lower == THERMAL_NO_LIMIT ? 0 : lower;
+	if (lower == THERMAL_NO_LIMIT)
+		lower = 0;

 	if (upper == THERMAL_NO_LIMIT) {
 		upper = cdev->max_state;