netdev - Re: [Oops] fib_trie with ip route add throw since 2.6.25

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Date:	Tue, 8 Jul 2008 15:52:56 -0700
From:	Stephen Hemminger <stephen.hemminger@...tta.com>
To:	Ben Hutchings <bhutchings@...arflare.com>
Cc:	William Boughton <bill@...ghton.de>, netdev@...r.kernel.org
Subject: Re: [Oops] fib_trie with ip route add throw since 2.6.25

On Mon, 7 Jul 2008 20:57:45 +0100
Ben Hutchings <bhutchings@...arflare.com> wrote:

> William Boughton wrote:
> > 
> > Hello,
> 
> Hello again!
> 
> > ip route add throw 192.168.0.1
> > 
> > ping 192.168.0.1
> > 
> > Oppses when CONFIG_IP_FIB_TRIE=y
> > 
> > Reproduced on both x86_64 and 32 on Xen and a normal
> > kernel running in qemu/kvm.
> > 
> > It seems this problem was introduced in 2.6.25
> > 
> > git bisect reports that it may have been caused by:
> > 
> > a07f5f508a4d9728c8e57d7f66294bf5b254ff7f is first bad commit                    
> > commit a07f5f508a4d9728c8e57d7f66294bf5b254ff7f                                 
> > Author: Stephen Hemminger <stephen.hemminger@...tta.com>                        
> > Date:   Tue Jan 22 21:53:36 2008 -0800                                          
> >                                                                                 
> >     [IPV4] fib_trie: style cleanup                                              
> >                                                                                 
> >     Style cleanups:                                                             
> >           * make check_leaf return -1 or plen, rather than by reference         
> [...]
> 
> The changes to check_leaf() and fn_trie_lookup() seem to be wrong - where
> fn_trie_lookup() would previously return a negative error value from
> check_leaf(), it now returns 0.
> 
> Now fn_trie_lookup() doesn't appear to care about plen, so we could revert
> check_leaf() to returning the error value.  How does this work?
> 
> diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
> index 394db9c..43ed894 100644
> --- a/net/ipv4/fib_trie.c
> +++ b/net/ipv4/fib_trie.c
> @@ -1357,17 +1357,17 @@ static int check_leaf(struct trie *t, struct leaf *l,
>  			t->stats.semantic_match_miss++;
>  #endif
>  		if (err <= 0)
> -			return plen;
> +			return err;
>  	}
>  
> -	return -1;
> +	return 1;
>  }
>  
>  static int fn_trie_lookup(struct fib_table *tb, const struct flowi *flp,
>  			  struct fib_result *res)
>  {
>  	struct trie *t = (struct trie *) tb->tb_data;
> -	int plen, ret = 0;
> +	int ret;
>  	struct node *n;
>  	struct tnode *pn;
>  	int pos, bits;
> @@ -1391,10 +1391,7 @@ static int fn_trie_lookup(struct fib_table *tb, const struct flowi *flp,
>  
>  	/* Just a leaf? */
>  	if (IS_LEAF(n)) {
> -		plen = check_leaf(t, (struct leaf *)n, key, flp, res);
> -		if (plen < 0)
> -			goto failed;
> -		ret = 0;
> +		ret = check_leaf(t, (struct leaf *)n, key, flp, res);
>  		goto found;
>  	}
>  
> @@ -1419,11 +1416,9 @@ static int fn_trie_lookup(struct fib_table *tb, const struct flowi *flp,
>  		}
>  
>  		if (IS_LEAF(n)) {
> -			plen = check_leaf(t, (struct leaf *)n, key, flp, res);
> -			if (plen < 0)
> +			ret = check_leaf(t, (struct leaf *)n, key, flp, res);
> +			if (ret > 0)
>  				goto backtrace;
> -
> -			ret = 0;
>  			goto found;
>  		}
> --- END ---
> 
> Ben.
> 
> -- 
> Ben Hutchings, Senior Software Engineer, Solarflare Communications
> Not speaking for my employer; that's the marketing department's job.

Please resend this patch with proper DCO line
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