[v2,2/2] net/mlx4_core: clean up srq_res_start_move_to()

Building resource_tracker.o triggers a GCC warning:
    drivers/net/ethernet/mellanox/mlx4/resource_tracker.c: In function 'mlx4_HW2SW_SRQ_wrapper':
    drivers/net/ethernet/mellanox/mlx4/resource_tracker.c:3202:17: warning: 'srq' may be used uninitialized in this function [-Wmaybe-uninitialized]
      atomic_dec(&srq->mtt->ref_count);
                     ^

This is a false positive. But a cleanup of srq_res_start_move_to() can
help GCC here. The code currently uses a switch statement where a plain
if/else would do, since only two of the switch's four cases can ever
occur. Dropping that switch makes the warning go away.

While we're at it, add some missing braces, and convert state to the
correct type.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
---
v2: adjust to Jack's review.

 .../net/ethernet/mellanox/mlx4/resource_tracker.c  | 46 ++++++++--------------
 1 file changed, 16 insertions(+), 30 deletions(-)

ACK.  OK.

-Jack

On Tue, 14 Jan 2014 20:46:52 +0100
Paul Bolle <pebolle@tiscali.nl> wrote:

> Building resource_tracker.o triggers a GCC warning:
>     drivers/net/ethernet/mellanox/mlx4/resource_tracker.c: In
> function 'mlx4_HW2SW_SRQ_wrapper':
> drivers/net/ethernet/mellanox/mlx4/resource_tracker.c:3202:17:
> warning: 'srq' may be used uninitialized in this function
> [-Wmaybe-uninitialized] atomic_dec(&srq->mtt->ref_count); ^
> 
> This is a false positive. But a cleanup of srq_res_start_move_to() can
> help GCC here. The code currently uses a switch statement where a
> plain if/else would do, since only two of the switch's four cases can
> ever occur. Dropping that switch makes the warning go away.
> 
> While we're at it, add some missing braces, and convert state to the
> correct type.
> 
> Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
> ---
> v2: adjust to Jack's review.
> 
>  .../net/ethernet/mellanox/mlx4/resource_tracker.c  | 46
> ++++++++-------------- 1 file changed, 16 insertions(+), 30
> deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c
> b/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c index
> 15cd659..4acd84c 100644 ---
> a/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c +++
> b/drivers/net/ethernet/mellanox/mlx4/resource_tracker.c @@ -1371,7
> +1371,7 @@ static int cq_res_start_move_to(struct mlx4_dev *dev, int
> slave, int cqn, } 
>  static int srq_res_start_move_to(struct mlx4_dev *dev, int slave,
> int index,
> -				 enum res_cq_states state, struct
> res_srq **srq)
> +				 enum res_srq_states state, struct
> res_srq **srq) {
>  	struct mlx4_priv *priv = mlx4_priv(dev);
>  	struct mlx4_resource_tracker *tracker =
> &priv->mfunc.master.res_tracker; @@ -1380,39 +1380,25 @@ static int
> srq_res_start_move_to(struct mlx4_dev *dev, int slave, int index, 
>  	spin_lock_irq(mlx4_tlock(dev));
>  	r = res_tracker_lookup(&tracker->res_tree[RES_SRQ], index);
> -	if (!r)
> +	if (!r) {
>  		err = -ENOENT;
> -	else if (r->com.owner != slave)
> +	} else if (r->com.owner != slave) {
>  		err = -EPERM;
> -	else {
> -		switch (state) {
> -		case RES_SRQ_BUSY:
> -			err = -EINVAL;
> -			break;
> -
> -		case RES_SRQ_ALLOCATED:
> -			if (r->com.state != RES_SRQ_HW)
> -				err = -EINVAL;
> -			else if (atomic_read(&r->ref_count))
> -				err = -EBUSY;
> -			break;
> -
> -		case RES_SRQ_HW:
> -			if (r->com.state != RES_SRQ_ALLOCATED)
> -				err = -EINVAL;
> -			break;
> -
> -		default:
> +	} else if (state == RES_SRQ_ALLOCATED) {
> +		if (r->com.state != RES_SRQ_HW)
>  			err = -EINVAL;
> -		}
> +		else if (atomic_read(&r->ref_count))
> +			err = -EBUSY;
> +	} else if (state != RES_SRQ_HW || r->com.state !=
> RES_SRQ_ALLOCATED) {
> +		err = -EINVAL;
> +	}
>  
> -		if (!err) {
> -			r->com.from_state = r->com.state;
> -			r->com.to_state = state;
> -			r->com.state = RES_SRQ_BUSY;
> -			if (srq)
> -				*srq = r;
> -		}
> +	if (!err) {
> +		r->com.from_state = r->com.state;
> +		r->com.to_state = state;
> +		r->com.state = RES_SRQ_BUSY;
> +		if (srq)
> +			*srq = r;
>  	}
>  
>  	spin_unlock_irq(mlx4_tlock(dev));

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From: Paul Bolle <pebolle@tiscali.nl>
Date: Tue, 14 Jan 2014 20:46:52 +0100

> Building resource_tracker.o triggers a GCC warning:
>     drivers/net/ethernet/mellanox/mlx4/resource_tracker.c: In function 'mlx4_HW2SW_SRQ_wrapper':
>     drivers/net/ethernet/mellanox/mlx4/resource_tracker.c:3202:17: warning: 'srq' may be used uninitialized in this function [-Wmaybe-uninitialized]
>       atomic_dec(&srq->mtt->ref_count);
>                      ^
> 
> This is a false positive. But a cleanup of srq_res_start_move_to() can
> help GCC here. The code currently uses a switch statement where a plain
> if/else would do, since only two of the switch's four cases can ever
> occur. Dropping that switch makes the warning go away.
> 
> While we're at it, add some missing braces, and convert state to the
> correct type.
> 
> Signed-off-by: Paul Bolle <pebolle@tiscali.nl>

Applied.
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