FAILED: patch "[PATCH] ACPI: battery: Fix possible crash when unregistering a" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 76959aff14a0012ad6b984ec7686d163deccdc16
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024100726-skeleton-decal-096d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

76959aff14a0 ("ACPI: battery: Fix possible crash when unregistering a battery hook") 86309cbed261 ("ACPI: battery: Simplify battery hook locking")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 76959aff14a0012ad6b984ec7686d163deccdc16 Mon Sep 17 00:00:00 2001
From: Armin Wolf <[email protected]>
Date: Tue, 1 Oct 2024 23:28:34 +0200
Subject: [PATCH] ACPI: battery: Fix possible crash when unregistering a
battery hook

When a battery hook returns an error when adding a new battery, then the battery hook is automatically unregistered.
However the battery hook provider cannot know that, so it will later call battery_hook_unregister() on the already unregistered battery hook, resulting in a crash.

Fix this by using the list head to mark already unregistered battery hooks as already being unregistered so that they can be ignored by battery_hook_unregister().

index dda59ee5a11e..1c45ff6dbb83 100644
@@ -715,7 +715,7 @@ static void battery_hook_unregister_unlocked(struct acpi_battery_hook *hook)
 		if (!hook->remove_battery(battery->bat, hook))
 			power_supply_changed(battery->bat);
 	}
-	list_del(&hook->list);
+	list_del_init(&hook->list);
 
 	pr_info("extension unregistered: %s\n", hook->name);
 }

@@ -723,7 +723,14 @@ static void battery_hook_unregister_unlocked(struct acpi_battery_hook *hook)
 void battery_hook_unregister(struct acpi_battery_hook *hook)
 {
 	mutex_lock(&hook_mutex);
-	battery_hook_unregister_unlocked(hook);
+	/*
+	 * Ignore already unregistered battery hooks. This might happen
+	 * if a battery hook was previously unloaded due to an error when
+	 * adding a new battery.
+	 */
+	if (!list_empty(&hook->list))
+		battery_hook_unregister_unlocked(hook);
+
 	mutex_unlock(&hook_mutex);
 }
 EXPORT_SYMBOL_GPL(battery_hook_unregister);

@@ -733,7 +740,6 @@ void battery_hook_register(struct acpi_battery_hook *hook)
 	struct acpi_battery *battery;
 
 	mutex_lock(&hook_mutex);
-	INIT_LIST_HEAD(&hook->list);
 	list_add(&hook->list, &battery_hook_list);
 	/*
 	 * Now that the driver is registered, we need