Subject: Re: [PATCH net] vxlan: eliminate cached dst leak

From: Paolo Abeni <[email-masked]>
Date: Tue, 30 May 2017 10:34:48 +0200

On Mon, 2017-05-29 at 13:25 -0400, Lance Richardson wrote:
> After commit 0c1d70af924b ("net: use dst_cache for vxlan device"),
> cached dst entries could be leaked when more than one remote was
> present for a given vxlan_fdb entry, causing subsequent netns
> operations to block indefinitely and "unregister_netdevice: waiting
> for lo to become free." messages to appear in the kernel log.
> 
> Fix by properly releasing cached dst and freeing resources in this
> case.
> 
> Fixes: commit 0c1d70af924b ("net: use dst_cache for vxlan device")
> Signed-off-by: Lance Richardson <[email-masked]>
> ---
>  drivers/net/vxlan.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index 328b471..5c1d69e 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -740,6 +740,22 @@ static void vxlan_fdb_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f)
>  	call_rcu(&f->rcu, vxlan_fdb_free);
>  }
>  
> +static void vxlan_dst_free(struct rcu_head *head)
> +{
> +	struct vxlan_rdst *rd = container_of(head, struct vxlan_rdst, rcu);
> +
> +	dst_cache_destroy(&rd->dst_cache);
> +	kfree(rd);
> +}
> +
> +static void vxlan_fdb_dst_destroy(struct vxlan_dev *vxlan, struct vxlan_fdb *f,
> +				  struct vxlan_rdst *rd)
> +{
> +	list_del_rcu(&rd->list);
> +	vxlan_fdb_notify(vxlan, f, rd, RTM_DELNEIGH);
> +	call_rcu(&rd->rcu, vxlan_dst_free);
> +}
> +
>  static int vxlan_fdb_parse(struct nlattr *tb[], struct vxlan_dev *vxlan,
>  			   union vxlan_addr *ip, __be16 *port, __be32 *src_vni,
>  			   __be32 *vni, u32 *ifindex)
> @@ -864,9 +880,7 @@ static int __vxlan_fdb_delete(struct vxlan_dev *vxlan,
>  	 * otherwise destroy the fdb entry
>  	 */
>  	if (rd && !list_is_singular(&f->remotes)) {
> -		list_del_rcu(&rd->list);
> -		vxlan_fdb_notify(vxlan, f, rd, RTM_DELNEIGH);
> -		kfree_rcu(rd, rcu);
> +		vxlan_fdb_dst_destroy(vxlan, f, rd);
>  		goto out;
>  	}
>  

LGTM, thanks Lance!

Acked-by: Paolo Abeni <[email-masked]>