netdev - Re: [PATCH] usbnet: fix skb traversing races during unlink

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Message-Id: <20120428.221832.360259077795872366.davem@davemloft.net>
Date:	Sat, 28 Apr 2012 22:18:32 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	tom.leiming@...il.com
Cc:	gregkh@...uxfoundation.org, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, huajun.li.lee@...il.com,
	oneukum@...e.de, stable@...nel.org
Subject: Re: [PATCH] usbnet: fix skb traversing races during unlink

From: Ming Lei <tom.leiming@...il.com>
Date: Fri, 27 Apr 2012 18:21:35 +0800

> +/*The caller must hold list->lock*/

Please put spaces in your comments, like this:

/* The caller must hold list->lock */

> +
> +		/*speedup unlink by blocking resubmit*/

Same here.
>  
> -		entry = (struct skb_data *) skb->cb;
> +		skb_queue_walk(q, skb) {
> +			entry = (struct skb_data *) skb->cb;
> +			if (entry->state != unlink_start)
> +				break;
> +		}
> +		if (skb == (struct sk_buff *)q)
> +			break;

Please do not expose the internal details of SKB lists
with a test like this.  Eventually this will all be
converted to struct list_head and this kind of test
will cause unnecessary pain for such a conversion.

Instead, code it like this, as you would for a loop
using list_for_each*() or similar:

	skb_queue_walk(q, skb) {
		if (condition)
			goto found;
	}
	/* No matching entry. */
	break;
found:

Thanks.
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