Linux Ethernet Bridging - Mar 2018 - [Bridge] [PATCH net-next 1/5] bridge: initialize port flags with switchdev defaults

Default bridge port flags for switchdev devices can be different from
what is used in bridging core. Get default value from switchdev itself
on port initialization.

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os at quantenna.com>
---
 net/bridge/br_if.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 9ba4ed6..d658b55 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -342,6 +342,21 @@ static int find_portno(struct net_bridge *br)
 	return (index >= BR_MAX_PORTS) ? -EXFULL : index;
 }
 
+static unsigned long nbp_flags_get_default(struct net_device *dev)
+{
+	struct switchdev_attr attr = {
+		.orig_dev = dev,
+		.id = SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS,
+	};
+	int ret;
+
+	ret = switchdev_port_attr_get(dev, &attr);
+	if (ret)
+		return BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD;
+	else
+		return attr.u.brport_flags;
+}
+
 /* called with RTNL but without bridge lock */
 static struct net_bridge_port *new_nbp(struct net_bridge *br,
 				       struct net_device *dev)
@@ -363,7 +378,7 @@ static struct net_bridge_port *new_nbp(struct net_bridge
*br,
 	p->path_cost = port_cost(dev);
 	p->priority = 0x8000 >> BR_PORT_BITS;
 	p->port_no = index;
-	p->flags = BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD;
+	p->flags = nbp_flags_get_default(dev);
 	br_init_port(p);
 	br_set_state(p, BR_STATE_DISABLED);
 	br_stp_port_timer_init(p);
-- 
2.9.5

On Fri, Mar 09, 2018 at 07:03:04PM -0800, Igor Mitsyanko
wrote:
> Default bridge port flags for switchdev devices can be different from
> what is used in bridging core. Get default value from switchdev itself
> on port initialization.
> 
> Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os at quantenna.com>
> ---
>  net/bridge/br_if.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index 9ba4ed6..d658b55 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -342,6 +342,21 @@ static int find_portno(struct net_bridge *br)
>  	return (index >= BR_MAX_PORTS) ? -EXFULL : index;
>  }
>  
> +static unsigned long nbp_flags_get_default(struct net_device *dev)
> +{
> +	struct switchdev_attr attr = {
> +		.orig_dev = dev,
> +		.id = SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS,
> +	};
> +	int ret;
> +
> +	ret = switchdev_port_attr_get(dev, &attr);
> +	if (ret)
> +		return BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD;

Hi Igor

Please check if ret == -EOPNOTSUPP and only then use the defaults. A
real error should be propagated, causing new_nbp to fail. You might
also consider what to do when ENODATA is returned.

     Andrew

On Fri,  9 Mar 2018 19:03:04 -0800
Igor Mitsyanko <igor.mitsyanko.os at quantenna.com> wrote:
> Default bridge port flags for switchdev devices can be different from
> what is used in bridging core. Get default value from switchdev itself
> on port initialization.
> 
> Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os at quantenna.com>
> ---
Yes hardware devices may come it with different default values.
But the user experience on Linux needs to be consistent.

Instead, it makes more sense to me for each device driver using switchdev
to program to the values that it sees in the bridge.

Please revise this.