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List:       linux-kernel
Subject:    Re: [PATCH net 3/3] net: skb_queue_purge(): lock/unlock the queue only once
From:       Stephen Hemminger <stephen () networkplumber ! org>
Date:       2017-10-02 0:59:09
Message-ID: 20171001175909.4b9e53d8 () xeon-e3
[Download RAW message or body]

On Sun, 01 Oct 2017 22:19:20 -0000
Michael Witten <mfwitten@gmail.com> wrote:

> +	spin_lock_irqsave(&q->lock, flags);
> +	skb = q->next;
> +	__skb_queue_head_init(q);
> +	spin_unlock_irqrestore(&q->lock, flags);

Other code manipulating lists uses splice operation and
a sk_buff_head temporary on the stack. That would be easier
to understand.

	struct sk_buf_head head;

	__skb_queue_head_init(&head);
	spin_lock_irqsave(&q->lock, flags);
	skb_queue_splice_init(q, &head);
	spin_unlock_irqrestore(&q->lock, flags);


> +	while (skb != head) {
> +		next = skb->next;
>  		kfree_skb(skb);
> +		skb = next;
> +	}

It would be cleaner if you could use
skb_queue_walk_safe rather than open coding the loop.

	skb_queue_walk_safe(&head, skb,  tmp)
		kfree_skb(skb);


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