netdev - Re: [PATCH net 5/5] ipv4: nexthop version of fib_info_nh_uses

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Message-ID: <b4458d2c-6957-3adf-0553-6afcf2df7d42@cumulusnetworks.com>
Date:   Tue, 26 May 2020 18:10:00 +0300
From:   Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:     David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org,
        David Ahern <dsahern@...il.com>
Subject: Re: [PATCH net 5/5] ipv4: nexthop version of fib_info_nh_uses_dev

On 26/05/2020 18:01, David Ahern wrote:
> From: David Ahern <dsahern@...il.com>
> 
> Similar to the last path, need to fix fib_info_nh_uses_dev for
> external nexthops to avoid referencing multiple nh_grp structs.
> Move the device check in fib_info_nh_uses_dev to a helper and
> create a nexthop version that is called if the fib_info uses an
> external nexthop.
> 
> Fixes: 430a049190de ("nexthop: Add support for nexthop groups")
> Signed-off-by: David Ahern <dsahern@...il.com>
> ---
>  include/net/ip_fib.h    | 10 ++++++++++
>  include/net/nexthop.h   | 25 +++++++++++++++++++++++++
>  net/ipv4/fib_frontend.c | 19 ++++++++++---------
>  3 files changed, 45 insertions(+), 9 deletions(-)
> 

Acked-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>

> diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
> index 1f1dd22980e4..6683558db7c9 100644
> --- a/include/net/ip_fib.h
> +++ b/include/net/ip_fib.h
> @@ -448,6 +448,16 @@ static inline int fib_num_tclassid_users(struct net *net)
>  #endif
>  int fib_unmerge(struct net *net);
>  
> +static inline bool nhc_l3mdev_matches_dev(const struct fib_nh_common *nhc,
> +const struct net_device *dev)
> +{
> +	if (nhc->nhc_dev == dev ||
> +	    l3mdev_master_ifindex_rcu(nhc->nhc_dev) == dev->ifindex)
> +			return true;
> +
> +	return false;
> +}
> +
>  /* Exported by fib_semantics.c */
>  int ip_fib_check_default(__be32 gw, struct net_device *dev);
>  int fib_sync_down_dev(struct net_device *dev, unsigned long event, bool force);
> diff --git a/include/net/nexthop.h b/include/net/nexthop.h
> index 9414ae46fc1c..35680a8c2a1c 100644
> --- a/include/net/nexthop.h
> +++ b/include/net/nexthop.h
> @@ -266,6 +266,31 @@ struct fib_nh_common *nexthop_get_nhc_lookup(const struct nexthop *nh,
>  	return NULL;
>  }
>  
> +static inline bool nexthop_uses_dev(const struct nexthop *nh,
> +				    const struct net_device *dev)
> +{
> +	struct nh_info *nhi;
> +
> +	if (nh->is_group) {
> +		struct nh_group *nhg = rcu_dereference(nh->nh_grp);
> +		int i;
> +
> +		for (i = 0; i < nhg->num_nh; i++) {
> +			struct nexthop *nhe = nhg->nh_entries[i].nh;
> +
> +			nhi = rcu_dereference(nhe->nh_info);
> +			if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
> +				return true;
> +                }
> +        } else {
> +		nhi = rcu_dereference(nh->nh_info);
> +		if (nhc_l3mdev_matches_dev(&nhi->fib_nhc, dev))
> +			return true;
> +        }
> +
> +	return false;
> +}
> +
>  static inline unsigned int fib_info_num_path(const struct fib_info *fi)
>  {
>  	if (unlikely(fi->nh))
> diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
> index 213be9c050ad..aebb50735c68 100644
> --- a/net/ipv4/fib_frontend.c
> +++ b/net/ipv4/fib_frontend.c
> @@ -309,17 +309,18 @@ bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev)
>  {
>  	bool dev_match = false;
>  #ifdef CONFIG_IP_ROUTE_MULTIPATH
> -	int ret;
> +	if (unlikely(fi->nh)) {
> +		dev_match = nexthop_uses_dev(fi->nh, dev);
> +	} else {
> +		int ret;
>  
> -	for (ret = 0; ret < fib_info_num_path(fi); ret++) {
> -		const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);
> +		for (ret = 0; ret < fib_info_num_path(fi); ret++) {
> +			const struct fib_nh_common *nhc = fib_info_nhc(fi, ret);
>  
> -		if (nhc->nhc_dev == dev) {
> -			dev_match = true;
> -			break;
> -		} else if (l3mdev_master_ifindex_rcu(nhc->nhc_dev) == dev->ifindex) {
> -			dev_match = true;
> -			break;
> +			if (nhc_l3mdev_matches_dev(nhc, dev)) {
> +				dev_match = true;
> +				break;
> +			}
>  		}
>  	}
>  #else
>