[PATCH] sysfs: (driver/pci) if show/store is missing return -EIO

sysfs: fix drivers/pci so if an attribute does not implement
       show or store method read/write will return -EIO
       instead of 0.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index cf2cff7..e65bf2b 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -335,13 +335,14 @@
 {
 	struct device_driver *driver = kobj_to_pci_driver(kobj);
 	struct driver_attribute *dattr = attr_to_driver_attribute(attr);
-	ssize_t ret = 0;
+	ssize_t ret;
 
-	if (get_driver(driver)) {
-		if (dattr->show)
-			ret = dattr->show(driver, buf);
-		put_driver(driver);
-	}
+	if (!get_driver(driver))
+		return -ENODEV;
+
+	ret = dattr->show ? dattr->show(driver, buf) : -EIO;
+
+	put_driver(driver);
 	return ret;
 }
 
@@ -351,13 +352,14 @@
 {
 	struct device_driver *driver = kobj_to_pci_driver(kobj);
 	struct driver_attribute *dattr = attr_to_driver_attribute(attr);
-	ssize_t ret = 0;
+	ssize_t ret;
 
-	if (get_driver(driver)) {
-		if (dattr->store)
-			ret = dattr->store(driver, buf, count);
-		put_driver(driver);
-	}
+	if (!get_driver(driver))
+		return -ENODEV;
+
+	ret = dattr->store ? dattr->store(driver, buf, count) : -EIO;
+
+	put_driver(driver);
 	return ret;
 }