linux-kernel - [PATCH] gpio/gpio-sysfs: Try to export busy GPIO line leads to wrong GPIO line exporting

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Date:	Sun, 13 Nov 2011 03:30:57 +0200
From:	Denis Kuzmenko <linux@...onet.org.ua>
To:	Grant Likely <grant.likely@...retlab.ca>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] gpio/gpio-sysfs: Try to export busy GPIO line leads to wrong
 GPIO line exporting

From: Denis Kuzmenko <linux@...onet.org.ua>

Fix bug in gpio-sysfs interface (export of busy GPIO line leads to export of different GPIO line).

Signed-off-by: Denis Kuzmenko <linux@...onet.org.ua>
---

Patch is against 3.0.9
When trying to export GPIO line 37(40) which is already exported/requested by kernel code we got GPIO line 3(4) exported.
Looks like this is done because `export_store` function doesn't return the number of processed bytes and gets a part of previous buffer again.
This fix works for me (Samsung s3c2440).

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a971e3d..ccec497 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -633,7 +633,7 @@ static ssize_t export_store(struct class *class,
 done:
 	if (status)
 		pr_debug("%s: status %d\n", __func__, status);
-	return status ? : len;
+	return len;
 }

 static ssize_t unexport_store(struct class *class,
--
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