netdev - Re: [PATCH 2/2] macvlan: Move broadcasts into a work queue

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Date:	Tue, 08 Apr 2014 10:14:12 -0700
From:	Joe Perches <joe@...ches.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH 2/2] macvlan: Move broadcasts into a work queue

On Tue, 2014-04-08 at 09:55 -0700, Stephen Hemminger wrote:
> On Mon, 07 Apr 2014 15:55:36 +0800
> Herbert Xu <herbert@...dor.apana.org.au> wrote:
> 
> > +static void macvlan_broadcast_enqueue(struct macvlan_port *port,
> > +				      struct sk_buff *skb)
> > +{
> > +	int err = -ENOMEM;
> > +
> > +	skb = skb_clone(skb, GFP_ATOMIC);
> > +	if (unlikely(!skb))
> > +		goto err;
> > +
> > +	spin_lock(&port->bc_queue.lock);
> > +	if (skb_queue_len(&port->bc_queue) < skb->dev->tx_queue_len) {
> > +		__skb_queue_tail(&port->bc_queue, skb);
> > +		err = 0;
> > +	}
> > +	spin_unlock(&port->bc_queue.lock);
> > +
> > +	if (unlikely(err)) {
> > +err:
> > +		atomic_long_inc(&skb->dev->rx_dropped);
> > +		return;
> > +	}
> > +
> 
> unlikely() with goto is redundant and unnecessary.
> 
> IMHO jumping into a block is bad code style
> 
> Why not just move err: to the end as in:
> 
> 
> 	skb = skb_clone(skb, GFP_ATOMIC);
> 	if (unlikely(!skb))
> 		goto err;
> 
> 	spin_lock(&port->bc_queue.lock);
> 	if (skb_queue_len(&port->bc_queue) < skb->dev->tx_queue_len) {
> 		__skb_queue_tail(&port->bc_queue, skb);
> 		err = 0;
> 	}
> 	spin_unlock(&port->bc_queue.lock);
> 
> 	if (err)
> 		goto err;
> 
> 	schedule_work(&port->bc_work);
> 	return;
> err:
> 
> 	atomic_long_inc(&skb->dev->rx_dropped);
> }

Perhaps the spin_unlock should be duplicated instead
and the "int err" removed.

static void macvlan_broadcast_enqueue(struct macvlan_port *port,
				      struct sk_buff *skb)
{
	skb = skb_clone(skb, GFP_ATOMIC);
	if (!skb)
		goto err;

	spin_lock(&port->bc_queue.lock);
	if (skb_queue_len(&port->bc_queue) >= skb->dev->tx_queue_len)
		goto err_unlock;

	__skb_queue_tail(&port->bc_queue, skb);
	spin_unlock(&port->bc_queue.lock);
	schedule_work(&port->bc_work);

	return;

err_unlock:
	spin_unlock(&port->bc_queue.lock);
err:
	atomic_long_inc(&skb->dev->rx_dropped);
}

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