Re: [PATCH] aoe: error printed 1 too early

[Ed Cashin]

On Wed, Feb 25, 2009 at 02:38:54PM +0100, Roel Kluin wrote:
> with while (i-- > 0); i reaches -1 after the loop, so the test below is printed
> one too early: 0 still means success.
> 
> Signed-off-by: Roel Kluin <roel.kluin@xxxxxxxxx>
> ---
> diff --git a/drivers/block/aoe/aoedev.c b/drivers/block/aoe/aoedev.c
> index cc25057..eeea477 100644
> --- a/drivers/block/aoe/aoedev.c
> +++ b/drivers/block/aoe/aoedev.c
> @@ -173,7 +173,7 @@ skbfree(struct sk_buff *skb)
>  		return;
>  	while (atomic_read(&skb_shinfo(skb)->dataref) != 1 && i-- > 0)
>  		msleep(Sms);
> -	if (i <= 0) {
> +	if (i < 0) {
>  		printk(KERN_ERR
>  			"aoe: %s holds ref: %s\n",
>  			skb->dev ? skb->dev->name : "netif",
> 

You are talking about the case where, when entering the loop on the
"last chance" iteration, the states are,

  atomic_read(&skb_shinfo(skb)->dataref == 1
  i == 0

... in which case, the skb can and should be used but is not used
because after the value of i is tested it becomes -1.

Right?

Sounds like a good catch.  Did you find it because you saw the "cannot
free skb" message?

-- 
  Ed Cashin <ecashin@xxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/