mtd: rawnand: atmel: fix possible object reference leak

of_find_device_by_node() takes a reference to the struct device
when it finds a match via get_device, there is no need to call
get_device() twice.
We also should make sure to drop the reference to the device
taken by of_find_device_by_node() on driver unbind.

Fixes: f88fc122cc ("mtd: nand: Cleanup/rework the atmel_nand driver")
Signed-off-by: Wen Yang <[email protected]>
Suggested-by: Boris Brezillon <[email protected]>
Reviewed-by: Boris Brezillon <[email protected]>
Reviewed-by: Miquel Raynal <[email protected]>
Acked-by: Miquel Raynal <[email protected]>
Cc: Tudor Ambarus <[email protected]>
Cc: Boris Brezillon <[email protected]>
Cc: Miquel Raynal <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Brian Norris <[email protected]>
Cc: Marek Vasut <[email protected]>
Cc: Nicolas Ferre <[email protected]>
Cc: Alexandre Belloni <[email protected]>
Cc: Ludovic Desroches <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Miquel Raynal <[email protected]>

drivers/mtd/nand/raw/atmel/pmecc.c

@@ -876,23 +876,32 @@ static struct atmel_pmecc *atmel_pmecc_get_by_node(struct device *userdev,
 {
 	struct platform_device *pdev;
 	struct atmel_pmecc *pmecc, **ptr;
+	int ret;
 
 	pdev = of_find_device_by_node(np);
-	if (!pdev || !platform_get_drvdata(pdev))
+	if (!pdev)
 		return ERR_PTR(-EPROBE_DEFER);
+	pmecc = platform_get_drvdata(pdev);
+	if (!pmecc) {
+		ret = -EPROBE_DEFER;
+		goto err_put_device;
+	}
 
 	ptr = devres_alloc(devm_atmel_pmecc_put, sizeof(*ptr), GFP_KERNEL);
-	if (!ptr)
-		return ERR_PTR(-ENOMEM);
-
-	get_device(&pdev->dev);
-	pmecc = platform_get_drvdata(pdev);
+	if (!ptr) {
+		ret = -ENOMEM;
+		goto err_put_device;
+	}
 
 	*ptr = pmecc;
 
 	devres_add(userdev, ptr);
 
 	return pmecc;
+
+err_put_device:
+	put_device(&pdev->dev);
+	return ERR_PTR(ret);
 }
 
 static const int atmel_pmecc_strengths[] = { 2, 4, 8, 12, 24, 32 };