Subject: Re: [RFC PATCH]: Fix a warning in the niu driver

From: Prarit Bhargava <[email-masked]>
Date: Wed, 14 Jul 2010 09:18:31 -0400

> Your patch would corrupt the list state, since we'd leave
> pages in the rx page hash which have only externally references
> and thus will be freed up.
>
>   

Ah ... I totally missed that.  Thanks for clarifying that Dave.

> Just BUG() if the loop terminates without finding a page.
>
> --------------------
> niu: BUG on inability to find page in rx page hashes.
>
> Signed-off-by: David S. Miller <[email-masked]>
>
> diff --git a/drivers/net/niu.c b/drivers/net/niu.c
> index 3d523cb..5d36531 100644
> --- a/drivers/net/niu.c
> +++ b/drivers/net/niu.c
> @@ -3330,10 +3330,12 @@ static struct page *niu_find_rxpage(struct rx_ring_info *rp, u64 addr,
>  	for (; (p = *pp) != NULL; pp = (struct page **) &p->mapping) {
>  		if (p->index == addr) {
>  			*link = pp;
> -			break;
> +			goto found;
>  		}
>  	}
> +	BUG();
>  
> +found:
>  	return p;
>  }
>   

Dave, would it be acceptable if I then wrapped link in
uninitialized_var() to get rid of the warning I'm trying to resolve?  It
seems that your patch then checks for a valid page value so it should be
okay.

P.