netdev - Re: [PATCH net-next 3/4] nexthop: Do not return invalid nexthop object during multipath selection

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Date: Wed, 31 May 2023 09:04:32 +0300
From: Ido Schimmel <idosch@...dia.com>
To: David Ahern <dsahern@...nel.org>
Cc: Benjamin Poirier <bpoirier@...dia.com>, netdev@...r.kernel.org,
	Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next 3/4] nexthop: Do not return invalid nexthop
 object during multipath selection

On Tue, May 30, 2023 at 09:08:01AM -0600, David Ahern wrote:
> On 5/29/23 2:19 PM, Benjamin Poirier wrote:
> > diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
> > index c12acbf39659..ca501ced04fb 100644
> > --- a/net/ipv4/nexthop.c
> > +++ b/net/ipv4/nexthop.c
> > @@ -1186,6 +1186,7 @@ static struct nexthop *nexthop_select_path_fdb(struct nh_group *nhg, int hash)
> >  static struct nexthop *nexthop_select_path_hthr(struct nh_group *nhg, int hash)
> >  {
> >  	struct nexthop *rc = NULL;
> > +	bool first = false;
> >  	int i;
> >  
> >  	if (nhg->fdb_nh)
> > @@ -1194,20 +1195,24 @@ static struct nexthop *nexthop_select_path_hthr(struct nh_group *nhg, int hash)
> >  	for (i = 0; i < nhg->num_nh; ++i) {
> >  		struct nh_grp_entry *nhge = &nhg->nh_entries[i];
> >  
> > -		if (hash > atomic_read(&nhge->hthr.upper_bound))
> > -			continue;
> > -
> >  		/* nexthops always check if it is good and does
> >  		 * not rely on a sysctl for this behavior
> >  		 */
> > -		if (nexthop_is_good_nh(nhge->nh))
> > -			return nhge->nh;
> > +		if (!nexthop_is_good_nh(nhge->nh))
> > +			continue;
> >  
> > -		if (!rc)
> > +		if (!first) {
> 
> Setting 'first' and 'rc' are equivalent, so 'first' is not needed.

Yea, looking at it again not sure what I was thinking...

Thanks for the review!

> As I recall it was used in fib_select_multipath before the nexthop
> refactoring (eba618abacade) because nhsel == 0 is valid, so the loop
> could not rely on it.
> 
> 
> 
> >  			rc = nhge->nh;
> > +			first = true;
> > +		}
> > +
> > +		if (hash > atomic_read(&nhge->hthr.upper_bound))
> > +			continue;
> > +
> > +		return nhge->nh;
> >  	}
> >  
> > -	return rc;
> > +	return rc ? : nhg->nh_entries[0].nh;
> >  }
> >  
> >  static struct nexthop *nexthop_select_path_res(struct nh_group *nhg, int hash)
> 
>