[PATCH] block: wrong return value

[PATCH] block: wrong return value

[Sudip Mukherjee]

while compiling integer err was showing as a set but unused variable.
elevator_init_fn can be either cfq_init_queue or deadline_init_queue
or noop_init_queue.
all three of these functions are returning -ENOMEM if they fail to
allocate the queue. 
so we should actually be returning the error code rather than
returning 0 always.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
---

hi,
if my understanding was wrong and if it is indeed a case of unusued variable,
   then please discard this patch.

 block/elevator.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/elevator.c b/block/elevator.c
index 24c28b6..7560417 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -184,7 +184,7 @@ static void elevator_release(struct kobject *kobj)
 int elevator_init(struct request_queue *q, char *name)
 {
 	struct elevator_type *e = NULL;
-	int err;
+	int err = 0;
 
 	/*
 	 * q->sysfs_lock must be held to provide mutual exclusion between
@@ -229,7 +229,7 @@ int elevator_init(struct request_queue *q, char *name)
 	}
 
 	err = e->ops.elevator_init_fn(q, e);
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL(elevator_init);
 
-- 
1.8.1.2

Re: [PATCH] block: wrong return value

[Jens Axboe]

On 10/23/2014 07:20 AM, Sudip Mukherjee wrote:
> while compiling integer err was showing as a set but unused variable.
> elevator_init_fn can be either cfq_init_queue or deadline_init_queue
> or noop_init_queue.
> all three of these functions are returning -ENOMEM if they fail to
> allocate the queue. 
> so we should actually be returning the error code rather than
> returning 0 always.

That does look weird. You need an elevator_put() in the error case,
though, ala:

err = e->ops.elevator_init_fn(q, e);
if (err)
	elevator_put(e);

return err;


-- 
Jens Axboe

Re: [PATCH] block: wrong return value

[Sudip Mukherjee]

On Thu, Oct 23, 2014 at 08:12:06AM -0600, Jens Axboe wrote:
> On 10/23/2014 07:20 AM, Sudip Mukherjee wrote:
> > while compiling integer err was showing as a set but unused variable.
> > elevator_init_fn can be either cfq_init_queue or deadline_init_queue
> > or noop_init_queue.
> > all three of these functions are returning -ENOMEM if they fail to
> > allocate the queue. 
> > so we should actually be returning the error code rather than
> > returning 0 always.
> 
> That does look weird. You need an elevator_put() in the error case,
> though, ala:
> 
oops.. sorry i missed that elevator_get in the code.
I will send you v2 of the patch.

thanks
sudip

> err = e->ops.elevator_init_fn(q, e);
> if (err)
> 	elevator_put(e);
> 
> return err;
> 
> 
> -- 
> Jens Axboe
>