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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Linus Walleij <linus.walleij@linaro.org>,
        Daniel Rosenberg <drosen@google.com>
Subject: [PATCH 4.4 15/24] gpio: No NULL owner
Date:   Thu, 14 Jun 2018 16:05:10 +0200
Message-Id: <20180614132725.096110374@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Walleij <linus.walleij@linaro.org>

commit 7d18f0a14aa6a0d6bad39111c1fb655f07f71d59 upstream.

Sometimes a GPIO is fetched with NULL as parent device, and
that is just fine. So under these circumstances, avoid using
dev_name() to provide a name for the GPIO line.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpio/gpiolib.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2117,6 +2117,8 @@ struct gpio_desc *__must_check gpiod_get
 	struct gpio_desc *desc = NULL;
 	int status;
 	enum gpio_lookup_flags lookupflags = 0;
+	/* Maybe we have a device name, maybe not */
+	const char *devname = dev ? dev_name(dev) : "?";
 
 	dev_dbg(dev, "GPIO lookup for consumer %s\n", con_id);
 
@@ -2145,8 +2147,11 @@ struct gpio_desc *__must_check gpiod_get
 		return desc;
 	}
 
-	/* If a connection label was passed use that, else use the device name as label */
-	status = gpiod_request(desc, con_id ? con_id : dev_name(dev));
+	/*
+	 * If a connection label was passed use that, else attempt to use
+	 * the device name as label
+	 */
+	status = gpiod_request(desc, con_id ? con_id : devname);
 	if (status < 0)
 		return ERR_PTR(status);