linux-kernel - [PATCH 3/3] platform/x86: dell-ddv: Fix taking the psy->extensions

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Message-Id: <20250627205325.250608-3-W_Armin@gmx.de>
Date: Fri, 27 Jun 2025 22:53:25 +0200
From: Armin Wolf <W_Armin@....de>
To: sre@...nel.org,
	hdegoede@...hat.com,
	ilpo.jarvinen@...ux.intel.com
Cc: linux-pm@...r.kernel.org,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux@...ssschuh.net
Subject: [PATCH 3/3] platform/x86: dell-ddv: Fix taking the psy->extensions_sem lock twice

Calling power_supply_get_property() inside
dell_wmi_ddv_battery_translate() can cause a deadlock since this
function is also being called from the power supply extension code,
in which case psy->extensions_sem is already being held.

Fix this by using the new power_supply_get_property_direct() function
to ignore any power supply extensions when retrieving the battery
serial number.

Tested on a Dell Inspiron 3505.

Reported-by: Hans de Goede <hansg@...nel.org>
Fixes: 058de163a376 ("platform/x86: dell-ddv: Implement the battery matching algorithm")
Signed-off-by: Armin Wolf <W_Armin@....de>
---
 drivers/platform/x86/dell/dell-wmi-ddv.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/x86/dell/dell-wmi-ddv.c
index 67f3d7158403..62e3d060f038 100644
--- a/drivers/platform/x86/dell/dell-wmi-ddv.c
+++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
@@ -689,9 +689,13 @@ static int dell_wmi_ddv_battery_translate(struct dell_wmi_ddv_data *data,
 
 	dev_dbg(&data->wdev->dev, "Translation cache miss\n");
 
-	/* Perform a translation between a ACPI battery and a battery index */
-
-	ret = power_supply_get_property(battery, POWER_SUPPLY_PROP_SERIAL_NUMBER, &val);
+	/*
+	 * Perform a translation between a ACPI battery and a battery index.
+	 * We have to use power_supply_get_property_direct() here because this
+	 * function will also get called from the callbacks of the power supply
+	 * extension.
+	 */
+	ret = power_supply_get_property_direct(battery, POWER_SUPPLY_PROP_SERIAL_NUMBER, &val);
 	if (ret < 0)
 		return ret;
 
-- 
2.39.5