Subject: Re: [RFC net-next v3 09/10] net: bridge: mrp: Integrate MRP into the bridge

From: Andrew Lunn <[email-masked]>
Date: Sat, 25 Jan 2020 16:42:48 +0100

On Fri, Jan 24, 2020 at 05:18:27PM +0100, Horatiu Vultur wrote:
> To integrate MRP into the bridge, the bridge needs to do the following:
> - initialized and destroy the generic netlink used by MRP
> - detect if the MRP frame was received on a port that is part of a MRP ring. In
>   case it was not, then forward the frame as usual, otherwise redirect the frame
>   to the upper layer.
> 
> Signed-off-by: Horatiu Vultur <[email-masked]>
> ---
>  net/bridge/br.c         | 11 +++++++++++
>  net/bridge/br_device.c  |  3 +++
>  net/bridge/br_if.c      |  6 ++++++
>  net/bridge/br_input.c   | 14 ++++++++++++++
>  net/bridge/br_private.h | 14 ++++++++++++++
>  5 files changed, 48 insertions(+)
> 
> diff --git a/net/bridge/br.c b/net/bridge/br.c
> index b6fe30e3768f..d5e556eed4ba 100644
> --- a/net/bridge/br.c
> +++ b/net/bridge/br.c
> @@ -344,6 +344,12 @@ static int __init br_init(void)
>  	if (err)
>  		goto err_out5;
>  
> +#ifdef CONFIG_BRIDGE_MRP
> +	err = br_mrp_netlink_init();
> +	if (err)
> +		goto err_out6;
> +#endif

Please try to avoid #ifdef's like this in C code. Add a stub function
to br_private_mrp.h.

If you really cannot avoid #ifdef, please use #if IS_ENABLED(CONFIG_BRIDGE_MRP).
That expands to

	if (0) {

        }

So the compiler will compile it and then optimize it out. That gives
us added benefit of build testing, we don't suddenly find the code no
longer compiles when we enable the option.

> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -21,6 +21,9 @@
>  #include <linux/rculist.h>
>  #include "br_private.h"
>  #include "br_private_tunnel.h"
> +#ifdef CONFIG_BRIDGE_MRP
> +#include "br_private_mrp.h"
> +#endif

It should always be safe to include a header file.

   Andrew