linux-kernel - [PATCH] driver core: platform: Emit a warning if a remove callback returned non-zero

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Date:   Sun,  7 Feb 2021 22:15:37 +0100
From:   Uwe Kleine-König <uwe@...ine-koenig.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] driver core: platform: Emit a warning if a remove callback returned non-zero

The driver core ignores the return value of a bus' remove callback. However
a driver returning an error code is a hint that there is a problem,
probably a driver author who expects that returning e.g. -EBUSY has any
effect.

The right thing to do would be to make struct platform_driver::remove()
return void. With the immense number of platform drivers this is however a
big quest and I hope to prevent at least a few new drivers that return an
error code here.

Signed-off-by: Uwe Kleine-König <uwe@...ine-koenig.org>
---
 drivers/base/platform.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 95fd1549f87d..1a869e277109 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1461,13 +1461,16 @@ static int platform_remove(struct device *_dev)
 {
 	struct platform_driver *drv = to_platform_driver(_dev->driver);
 	struct platform_device *dev = to_platform_device(_dev);
-	int ret = 0;
 
-	if (drv->remove)
-		ret = drv->remove(dev);
+	if (drv->remove) {
+		int ret = drv->remove(dev);
+
+		if (ret)
+			dev_warn(_dev, "remove callback returned a non-zero value. This will be ignored.\n");
+	}
 	dev_pm_domain_detach(_dev, true);
 
-	return ret;
+	return 0;
 }
 
 static void platform_shutdown(struct device *_dev)
-- 
2.29.2