linux-kernel - [PATCH v1] thermal: core: Drop excessive lockdep_assert

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Date:   Tue, 28 Mar 2023 20:43:26 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Imre Deak <imre.deak@...el.com>,
        Linux ACPI <linux-acpi@...r.kernel.org>
Subject: [PATCH v1] thermal: core: Drop excessive lockdep_assert_held() calls

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

The lockdep_assert_held() calls added to cooling_device_stats_setup()
and cooling_device_stats_destroy() by commit 790930f44289 ("thermal:
core: Introduce thermal_cooling_device_update()") trigger false-positive
lockdep reports in code paths that are not subject to race conditions
(before cooling device registration and after cooling device removal).

For this reason, remove the lockdep_assert_held() calls from both
cooling_device_stats_setup() and cooling_device_stats_destroy() and
add one to thermal_cooling_device_stats_reinit() that has to be called
under the cdev lock.

Fixes: 790930f44289 ("thermal: core: Introduce thermal_cooling_device_update()")
Link: https://lore.kernel.org/linux-acpi/ZCIDTLFt27Ei7+V6@ideak-desk.fi.intel.com
Reported-by: Imre Deak <imre.deak@...el.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/thermal/thermal_sysfs.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -876,8 +876,6 @@ static void cooling_device_stats_setup(s
 	unsigned long states = cdev->max_state + 1;
 	int var;
 
-	lockdep_assert_held(&cdev->lock);
-
 	var = sizeof(*stats);
 	var += sizeof(*stats->time_in_state) * states;
 	var += sizeof(*stats->trans_table) * states * states;
@@ -903,8 +901,6 @@ out:
 
 static void cooling_device_stats_destroy(struct thermal_cooling_device *cdev)
 {
-	lockdep_assert_held(&cdev->lock);
-
 	kfree(cdev->stats);
 	cdev->stats = NULL;
 }
@@ -931,6 +927,8 @@ void thermal_cooling_device_destroy_sysf
 
 void thermal_cooling_device_stats_reinit(struct thermal_cooling_device *cdev)
 {
+	lockdep_assert_held(&cdev->lock);
+
 	cooling_device_stats_destroy(cdev);
 	cooling_device_stats_setup(cdev);
 }