Re: [PATCH RFC v1 net-next 06/12] net: core: dev: Add dev_fill_bridge_path()

[Nikolay Aleksandrov]

On 13/10/2024 21:55, Eric Woudstra wrote:
> New function dev_fill_bridge_path(), similar to dev_fill_forward_path().
> It handles starting from a bridge port instead of the bridge master.
> The structures ctx and nft_forward_info need to be already filled in with
> the (vlan) encaps.
> 
> Signed-off-by: Eric Woudstra <ericwouds@xxxxxxxxx>
> ---
>  include/linux/netdevice.h |  2 +
>  net/core/dev.c            | 77 ++++++++++++++++++++++++++++++++-------
>  2 files changed, 66 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index e87b5e488325..9d80f650345e 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3069,6 +3069,8 @@ void dev_remove_offload(struct packet_offload *po);
>  
>  int dev_get_iflink(const struct net_device *dev);
>  int dev_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb);
> +int dev_fill_bridge_path(struct net_device_path_ctx *ctx,
> +			 struct net_device_path_stack *stack);
>  int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
>  			  struct net_device_path_stack *stack);
>  struct net_device *__dev_get_by_flags(struct net *net, unsigned short flags,
> diff --git a/net/core/dev.c b/net/core/dev.c
> index cd479f5f22f6..49959c4904fc 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -713,44 +713,95 @@ static struct net_device_path *dev_fwd_path(struct net_device_path_stack *stack)
>  	return &stack->path[k];
>  }
>  
> -int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
> -			  struct net_device_path_stack *stack)
> +static int dev_fill_forward_path_common(struct net_device_path_ctx *ctx,
> +					struct net_device_path_stack *stack)
>  {
>  	const struct net_device *last_dev;
> -	struct net_device_path_ctx ctx = {
> -		.dev	= dev,
> -	};
>  	struct net_device_path *path;
>  	int ret = 0;
>  
> -	memcpy(ctx.daddr, daddr, sizeof(ctx.daddr));
> -	stack->num_paths = 0;
> -	while (ctx.dev && ctx.dev->netdev_ops->ndo_fill_forward_path) {
> -		last_dev = ctx.dev;
> +	while (ctx->dev && ctx->dev->netdev_ops->ndo_fill_forward_path) {
> +		last_dev = ctx->dev;
>  		path = dev_fwd_path(stack);
>  		if (!path)
>  			return -1;
>  
>  		memset(path, 0, sizeof(struct net_device_path));
> -		ret = ctx.dev->netdev_ops->ndo_fill_forward_path(&ctx, path);
> +		ret = ctx->dev->netdev_ops->ndo_fill_forward_path(ctx, path);
>  		if (ret < 0)
>  			return -1;
>  
> -		if (WARN_ON_ONCE(last_dev == ctx.dev))
> +		if (WARN_ON_ONCE(last_dev == ctx->dev))
>  			return -1;
>  	}
>  
> -	if (!ctx.dev)
> +	if (!ctx->dev)
>  		return ret;
>  
>  	path = dev_fwd_path(stack);
>  	if (!path)
>  		return -1;
>  	path->type = DEV_PATH_ETHERNET;
> -	path->dev = ctx.dev;
> +	path->dev = ctx->dev;
> +
> +	return ret;
> +}
> +
> +int dev_fill_bridge_path(struct net_device_path_ctx *ctx,
> +			 struct net_device_path_stack *stack)
> +{
> +	const struct net_device *last_dev, *br_dev;
> +	struct net_device_path *path;
> +	int ret = 0;
> +
> +	stack->num_paths = 0;
> +
> +	if (!ctx->dev || !netif_is_bridge_port(ctx->dev))
> +		return -1;
> +
> +	br_dev = netdev_master_upper_dev_get_rcu((struct net_device *)ctx->dev);
> +	if (!br_dev || !br_dev->netdev_ops->ndo_fill_forward_path)
> +		return -1;
> +
> +	last_dev = ctx->dev;
> +	path = dev_fwd_path(stack);
> +	if (!path)
> +		return -1;
> +
> +	memset(path, 0, sizeof(struct net_device_path));
> +	ret = br_dev->netdev_ops->ndo_fill_forward_path(ctx, path);
> +	if (ret < 0)
> +		return -1;
> +
> +	if (!ctx->dev || WARN_ON_ONCE(last_dev == ctx->dev))
> +		return -1;
> +
> +	if (!netif_is_bridge_master(ctx->dev))

hmm, do we expect ctx->dev to be a bridge master? Looking at
br_fill_forward_path, it seems to be == fdb->dst->dev which
should be the target port

> +		return dev_fill_forward_path_common(ctx, stack);
> +
> +	path = dev_fwd_path(stack);
> +	if (!path)
> +		return -1;
> +	path->type = DEV_PATH_ETHERNET;
> +	path->dev = ctx->dev;
>  
>  	return ret;
>  }
> +EXPORT_SYMBOL_GPL(dev_fill_bridge_path);
> +
> +int dev_fill_forward_path(const struct net_device *dev, const u8 *daddr,
> +			  struct net_device_path_stack *stack)
> +{
> +	struct net_device_path_ctx ctx = {
> +		.dev	= dev,
> +	};
> +
> +	memcpy(ctx.daddr, daddr, sizeof(ctx.daddr));
> +
> +	stack->num_paths = 0;
> +
> +	return dev_fill_forward_path_common(&ctx, stack);
> +}
>  EXPORT_SYMBOL_GPL(dev_fill_forward_path);
>  
>  /**