Patch "ACPI: battery: Simplify battery hook locking" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ACPI: battery: Simplify battery hook locking

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     acpi-battery-simplify-battery-hook-locking.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9a7c13cafb4f74fd603f17119ee50e07faad39dc
Author: Armin Wolf <W_Armin@xxxxxx>
Date:   Tue Oct 1 23:28:33 2024 +0200

    ACPI: battery: Simplify battery hook locking
    
    [ Upstream commit 86309cbed26139e1caae7629dcca1027d9a28e75 ]
    
    Move the conditional locking from __battery_hook_unregister()
    into battery_hook_unregister() and rename the low-level function
    to simplify the locking during battery hook removal.
    
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
    Reviewed-by: Pali Rohár <pali@xxxxxxxxxx>
    Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
    Link: https://patch.msgid.link/20241001212835.341788-2-W_Armin@xxxxxx
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
    Stable-dep-of: 76959aff14a0 ("ACPI: battery: Fix possible crash when unregistering a battery hook")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index aed4132985a96..6a8580427e1a9 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -701,27 +701,27 @@ static LIST_HEAD(acpi_battery_list);
 static LIST_HEAD(battery_hook_list);
 static DEFINE_MUTEX(hook_mutex);
 
-static void __battery_hook_unregister(struct acpi_battery_hook *hook, int lock)
+static void battery_hook_unregister_unlocked(struct acpi_battery_hook *hook)
 {
 	struct acpi_battery *battery;
+
 	/*
 	 * In order to remove a hook, we first need to
 	 * de-register all the batteries that are registered.
 	 */
-	if (lock)
-		mutex_lock(&hook_mutex);
 	list_for_each_entry(battery, &acpi_battery_list, list) {
 		hook->remove_battery(battery->bat);
 	}
 	list_del(&hook->list);
-	if (lock)
-		mutex_unlock(&hook_mutex);
+
 	pr_info("extension unregistered: %s\n", hook->name);
 }
 
 void battery_hook_unregister(struct acpi_battery_hook *hook)
 {
-	__battery_hook_unregister(hook, 1);
+	mutex_lock(&hook_mutex);
+	battery_hook_unregister_unlocked(hook);
+	mutex_unlock(&hook_mutex);
 }
 EXPORT_SYMBOL_GPL(battery_hook_unregister);
 
@@ -747,7 +747,7 @@ void battery_hook_register(struct acpi_battery_hook *hook)
 			 * hooks.
 			 */
 			pr_err("extension failed to load: %s", hook->name);
-			__battery_hook_unregister(hook, 0);
+			battery_hook_unregister_unlocked(hook);
 			goto end;
 		}
 	}
@@ -784,7 +784,7 @@ static void battery_hook_add_battery(struct acpi_battery *battery)
 			 */
 			pr_err("error in extension, unloading: %s",
 					hook_node->name);
-			__battery_hook_unregister(hook_node, 0);
+			battery_hook_unregister_unlocked(hook_node);
 		}
 	}
 	mutex_unlock(&hook_mutex);
@@ -817,7 +817,7 @@ static void __exit battery_hook_exit(void)
 	 * need to remove the hooks.
 	 */
 	list_for_each_entry_safe(hook, ptr, &battery_hook_list, list) {
-		__battery_hook_unregister(hook, 1);
+		battery_hook_unregister(hook);
 	}
 	mutex_destroy(&hook_mutex);
 }