linux-kernel - Re: [net-next v2 01/11] net: bridge: extend the process of special frames

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Date:   Tue, 6 Oct 2020 14:13:15 +0000
From:   Nikolay Aleksandrov <nikolay@...dia.com>
To:     "bridge@...ts.linux-foundation.org" 
        <bridge@...ts.linux-foundation.org>,
        "henrik.bjoernlund@...rochip.com" <henrik.bjoernlund@...rochip.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jiri@...lanox.com" <jiri@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Roopa Prabhu <roopa@...dia.com>,
        "idosch@...lanox.com" <idosch@...lanox.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>
CC:     "horatiu.vultur@...rochip.com" <horatiu.vultur@...rochip.com>
Subject: Re: [net-next v2 01/11] net: bridge: extend the process of special
 frames

On Thu, 2020-10-01 at 10:30 +0000, Henrik Bjoernlund wrote:
> This patch extends the processing of frames in the bridge. Currently MRP
> frames needs special processing and the current implementation doesn't
> allow a nice way to process different frame types. Therefore try to
> improve this by adding a list that contains frame types that need
> special processing. This list is iterated for each input frame and if
> there is a match based on frame type then these functions will be called
> and decide what to do with the frame. It can process the frame then the
> bridge doesn't need to do anything or don't process so then the bridge
> will do normal forwarding.
> 
> Reviewed-by: Horatiu Vultur  <horatiu.vultur@...rochip.com>
> Signed-off-by: Henrik Bjoernlund  <henrik.bjoernlund@...rochip.com>
> ---
>  net/bridge/br_device.c  |  1 +
>  net/bridge/br_input.c   | 31 ++++++++++++++++++++++++++++++-
>  net/bridge/br_mrp.c     | 19 +++++++++++++++----
>  net/bridge/br_private.h | 18 ++++++++++++------
>  4 files changed, 58 insertions(+), 11 deletions(-)
> 

Hi,
Mostly looks good, one comment below.

> diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
> index 9a2fb4aa1a10..206c4ba51cd2 100644
> --- a/net/bridge/br_device.c
> +++ b/net/bridge/br_device.c
> [snip]
> @@ -380,3 +395,17 @@ rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
>  
>  	return br_handle_frame;
>  }
> +
> +void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
> +{
> +	hlist_add_head_rcu(&ft->list, &br->frame_type_list);
> +}
> +
> +void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
> +{
> +	struct br_frame_type *tmp;
> +
> +	hlist_for_each_entry(tmp, &br->frame_type_list, list)
> +		if (ft == tmp)
> +			hlist_del_rcu(&ft->list);

This hasn't crashed only because you're using hlist_del_rcu(), otherwise it's
wrong. You should use hlist_for_each_entry_safe() when deleting from the list
while walking it or you should end the walk after the delete since there can't
be two elements with the same address anyway.

Thanks,
 Nik