linux-kernel - [PATCH v3] driver core: platform: don't oops in platform

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Date:   Sun, 13 Dec 2020 02:55:33 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: [PATCH v3] driver core: platform: don't oops in platform_shutdown() on unbound devices

On shutdown the driver core calls the bus' shutdown callback also for
unbound devices. A driver's shutdown callback however is only called for
devices bound to this driver. Commit 9c30921fe799 ("driver core:
platform: use bus_type functions") changed the platform bus from driver
callbacks to bus callbacks, so the shutdown function must be prepared to
be called without a driver. Add the corresponding check in the shutdown
function.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Fixes: 9c30921fe799 ("driver core: platform: use bus_type functions")
---
 drivers/base/platform.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 0358dc3ea3ad..e9477e0bbca5 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1351,9 +1351,13 @@ static int platform_remove(struct device *_dev)
 
 static void platform_shutdown(struct device *_dev)
 {
-	struct platform_driver *drv = to_platform_driver(_dev->driver);
 	struct platform_device *dev = to_platform_device(_dev);
+	struct platform_driver *drv;
+
+	if (!_dev->driver)
+		return;
 
+	drv = to_platform_driver(_dev->driver);
 	if (drv->shutdown)
 		drv->shutdown(dev);
 }
-- 
2.29.2