netdev - Re: [PATCH v3 net-next 2/4] net: dsa: Link aggregation support

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Date:   Wed, 2 Dec 2020 12:07:36 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Tobias Waldekranz <tobias@...dekranz.com>
Cc:     davem@...emloft.net, kuba@...nel.org, andrew@...n.ch,
        vivien.didelot@...il.com, f.fainelli@...il.com,
        j.vosburgh@...il.com, vfalico@...il.com, andy@...yhouse.net,
        netdev@...r.kernel.org
Subject: Re: [PATCH v3 net-next 2/4] net: dsa: Link aggregation support

On Wed, Dec 02, 2020 at 10:13:54AM +0100, Tobias Waldekranz wrote:
> Monitor the following events and notify the driver when:
> 
> - A DSA port joins/leaves a LAG.
> - A LAG, made up of DSA ports, joins/leaves a bridge.
> - A DSA port in a LAG is enabled/disabled (enabled meaning
>   "distributing" in 802.3ad LACP terms).
> 
> Each LAG interface to which a DSA port is attached is represented by a
> `struct dsa_lag` which is globally reachable from the switch tree and
> from each associated port.
> 
> When a LAG joins a bridge, the DSA subsystem will treat that as each
> individual port joining the bridge. The driver may look at the port's
> LAG pointer to see if it is associated with any LAG, if that is
> required. This is analogue to how switchdev events are replicated out
> to all lower devices when reaching e.g. a LAG.
> 
> Signed-off-by: Tobias Waldekranz <tobias@...dekranz.com>
> ---
>  include/net/dsa.h  |  97 +++++++++++++++++++++++++++++++++
>  net/dsa/dsa2.c     |  51 ++++++++++++++++++
>  net/dsa/dsa_priv.h |  31 +++++++++++
>  net/dsa/port.c     | 132 +++++++++++++++++++++++++++++++++++++++++++++
>  net/dsa/slave.c    |  83 +++++++++++++++++++++++++---
>  net/dsa/switch.c   |  49 +++++++++++++++++
>  6 files changed, 437 insertions(+), 6 deletions(-)
> 
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 4e60d2610f20..aaa350b78c55 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -7,6 +7,7 @@
>  #ifndef __LINUX_NET_DSA_H
>  #define __LINUX_NET_DSA_H
>  
> +#include <linux/bitmap.h>
>  #include <linux/if.h>
>  #include <linux/if_ether.h>
>  #include <linux/list.h>
> @@ -71,6 +72,7 @@ enum dsa_tag_protocol {
>  
>  struct packet_type;
>  struct dsa_switch;
> +struct dsa_lag;
>  
>  struct dsa_device_ops {
>  	struct sk_buff *(*xmit)(struct sk_buff *skb, struct net_device *dev);
> @@ -149,6 +151,13 @@ struct dsa_switch_tree {
>  
>  	/* List of DSA links composing the routing table */
>  	struct list_head rtable;
> +
> +	/* Link aggregates */
> +	struct {
> +		struct dsa_lag *pool;
> +		unsigned long *busy;
> +		unsigned int num;

Can we get rid of the busy array and just look at the refcounts?
Can we also get rid of the "num" variable?

> +	} lags;
>  };