[PATCH 01/14] parport: return value of attach and parport_register_driver

[Sudip Mukherjee <sudipm.mukherjee@gmail.com>]

as of now, we are not checking if attach or parport_register_driver
has succeeded or failed. But attach can fail in the places where they
have been used. Lets check the return of attach, and if attach fails
then parport_register_driver should also fail. We can have multiple
parallel port so we only mark attach as failed only if it has never
returned a 0.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
---
 drivers/parport/share.c | 20 +++++++++++++++-----
 include/linux/parport.h |  2 +-
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/parport/share.c b/drivers/parport/share.c
index 3fa6624..640ce41 100644
--- a/drivers/parport/share.c
+++ b/drivers/parport/share.c
@@ -148,23 +148,33 @@ static void get_lowlevel_driver (void)
  *	callback, but if the driver wants to take a copy of the
  *	pointer it must call parport_get_port() to do so.
  *
- *	Returns 0 on success.  Currently it always succeeds.
+ *	Returns 0 on success.
  **/
 
 int parport_register_driver (struct parport_driver *drv)
 {
 	struct parport *port;
+	int ret, err;
+	bool attached = false;
 
 	if (list_empty(&portlist))
 		get_lowlevel_driver ();
 
 	mutex_lock(&registration_lock);
-	list_for_each_entry(port, &portlist, list)
-		drv->attach(port);
-	list_add(&drv->list, &drivers);
+	list_for_each_entry(port, &portlist, list) {
+		err = drv->attach(port);
+		if (err == 0)
+			attached = true;
+		else
+			ret = err;
+	}
+	if (attached) {
+		list_add(&drv->list, &drivers);
+		ret = 0;
+	}
 	mutex_unlock(&registration_lock);
 
-	return 0;
+	return ret;
 }
 
 /**
diff --git a/include/linux/parport.h b/include/linux/parport.h
index c22f125..9411065 100644
--- a/include/linux/parport.h
+++ b/include/linux/parport.h
@@ -249,7 +249,7 @@ struct parport {
 
 struct parport_driver {
 	const char *name;
-	void (*attach) (struct parport *);
+	int (*attach)(struct parport *);
 	void (*detach) (struct parport *);
 	struct list_head list;
 };
-- 
1.8.1.2