From 9295c01253b4eda5dc0b5a5b2e0fd321fe57010c Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@c-s.fr>
Date: Mon, 18 Dec 2017 11:08:31 +0100
Subject: [PATCH] gpio: sysfs: correct error handling on 'value' attribute
 read.

'value' attribute is supposed to only return 0 or 1 according to
the documentation.
With today's implementation, if gpiod_get_value_cansleep() fails
the printed 'value' is a negative value.

This patch ensures that an error is returned on read instead.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib-sysfs.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 3b2465bbd5e70..ef34b8f56bd1f 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -106,8 +106,12 @@ static ssize_t value_show(struct device *dev,
 
 	mutex_lock(&data->mutex);
 
-	status = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc));
+	status = gpiod_get_value_cansleep(desc);
+	if (status < 0)
+		goto err;
 
+	status = sprintf(buf, "%d\n", status);
+err:
 	mutex_unlock(&data->mutex);
 
 	return status;
-- 
GitLab