[PATCH net-next] net: bridge: propagate error code and extack from br_mc_disabled_update

[PATCH net-next] net: bridge: propagate error code and extack from br_mc_disabled_update

[Vladimir Oltean]

From: Florian Fainelli <f.fainelli@gmail.com>

Some Ethernet switches might only be able to support disabling multicast
flooding globally, which is an issue for example when several bridges
span the same physical device and request contradictory settings.

Propagate the return value of br_mc_disabled_update() such that this
limitation is transmitted correctly to user-space.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 net/bridge/br_multicast.c | 26 +++++++++++++++++++-------
 net/bridge/br_netlink.c   |  4 +++-
 net/bridge/br_private.h   |  3 ++-
 net/bridge/br_sysfs_br.c  |  8 +-------
 4 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 9d265447d654..7f861a6eb348 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1593,7 +1593,8 @@ static void br_multicast_port_group_rexmit(struct timer_list *t)
 	spin_unlock(&br->multicast_lock);
 }
 
-static void br_mc_disabled_update(struct net_device *dev, bool value)
+static int br_mc_disabled_update(struct net_device *dev, bool value,
+				 struct netlink_ext_ack *extack)
 {
 	struct switchdev_attr attr = {
 		.orig_dev = dev,
@@ -1602,11 +1603,13 @@ static void br_mc_disabled_update(struct net_device *dev, bool value)
 		.u.mc_disabled = !value,
 	};
 
-	switchdev_port_attr_set(dev, &attr, NULL);
+	return switchdev_port_attr_set(dev, &attr, extack);
 }
 
 int br_multicast_add_port(struct net_bridge_port *port)
 {
+	int err;
+
 	port->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
 	port->multicast_eht_hosts_limit = BR_MCAST_DEFAULT_EHT_HOSTS_LIMIT;
 
@@ -1618,8 +1621,12 @@ int br_multicast_add_port(struct net_bridge_port *port)
 	timer_setup(&port->ip6_own_query.timer,
 		    br_ip6_multicast_port_query_expired, 0);
 #endif
-	br_mc_disabled_update(port->dev,
-			      br_opt_get(port->br, BROPT_MULTICAST_ENABLED));
+	err = br_mc_disabled_update(port->dev,
+				    br_opt_get(port->br,
+					       BROPT_MULTICAST_ENABLED),
+				    NULL);
+	if (err)
+		return err;
 
 	port->mcast_stats = netdev_alloc_pcpu_stats(struct bridge_mcast_stats);
 	if (!port->mcast_stats)
@@ -3560,16 +3567,21 @@ static void br_multicast_start_querier(struct net_bridge *br,
 	rcu_read_unlock();
 }
 
-int br_multicast_toggle(struct net_bridge *br, unsigned long val)
+int br_multicast_toggle(struct net_bridge *br, unsigned long val,
+			struct netlink_ext_ack *extack)
 {
 	struct net_bridge_port *port;
 	bool change_snoopers = false;
+	int err = 0;
 
 	spin_lock_bh(&br->multicast_lock);
 	if (!!br_opt_get(br, BROPT_MULTICAST_ENABLED) == !!val)
 		goto unlock;
 
-	br_mc_disabled_update(br->dev, val);
+	err = br_mc_disabled_update(br->dev, val, extack);
+	if (err && err != -EOPNOTSUPP)
+		goto unlock;
+
 	br_opt_toggle(br, BROPT_MULTICAST_ENABLED, !!val);
 	if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) {
 		change_snoopers = true;
@@ -3607,7 +3619,7 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)
 			br_multicast_leave_snoopers(br);
 	}
 
-	return 0;
+	return err;
 }
 
 bool br_multicast_enabled(const struct net_device *dev)
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index f2b1343f8332..0456593aceec 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -1293,7 +1293,9 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
 	if (data[IFLA_BR_MCAST_SNOOPING]) {
 		u8 mcast_snooping = nla_get_u8(data[IFLA_BR_MCAST_SNOOPING]);
 
-		br_multicast_toggle(br, mcast_snooping);
+		err = br_multicast_toggle(br, mcast_snooping, extack);
+		if (err)
+			return err;
 	}
 
 	if (data[IFLA_BR_MCAST_QUERY_USE_IFADDR]) {
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index ecb91e13d777..947c724c26b2 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -812,7 +812,8 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
 			struct sk_buff *skb, bool local_rcv, bool local_orig);
 int br_multicast_set_router(struct net_bridge *br, unsigned long val);
 int br_multicast_set_port_router(struct net_bridge_port *p, unsigned long val);
-int br_multicast_toggle(struct net_bridge *br, unsigned long val);
+int br_multicast_toggle(struct net_bridge *br, unsigned long val,
+			struct netlink_ext_ack *extack);
 int br_multicast_set_querier(struct net_bridge *br, unsigned long val);
 int br_multicast_set_hash_max(struct net_bridge *br, unsigned long val);
 int br_multicast_set_igmp_version(struct net_bridge *br, unsigned long val);
diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 072e29840082..381467b691d5 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -409,17 +409,11 @@ static ssize_t multicast_snooping_show(struct device *d,
 	return sprintf(buf, "%d\n", br_opt_get(br, BROPT_MULTICAST_ENABLED));
 }
 
-static int toggle_multicast(struct net_bridge *br, unsigned long val,
-			    struct netlink_ext_ack *extack)
-{
-	return br_multicast_toggle(br, val);
-}
-
 static ssize_t multicast_snooping_store(struct device *d,
 					struct device_attribute *attr,
 					const char *buf, size_t len)
 {
-	return store_bridge_parm(d, buf, len, toggle_multicast);
+	return store_bridge_parm(d, buf, len, br_multicast_toggle);
 }
 static DEVICE_ATTR_RW(multicast_snooping);
 
-- 
2.25.1

Re: [PATCH net-next] net: bridge: propagate error code and extack from br_mc_disabled_update

[Nikolay Aleksandrov]

On 14/04/2021 17:34, Vladimir Oltean wrote:
> From: Florian Fainelli <f.fainelli@gmail.com>
> 
> Some Ethernet switches might only be able to support disabling multicast
> flooding globally, which is an issue for example when several bridges
> span the same physical device and request contradictory settings.
> 
> Propagate the return value of br_mc_disabled_update() such that this
> limitation is transmitted correctly to user-space.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
>  net/bridge/br_multicast.c | 26 +++++++++++++++++++-------
>  net/bridge/br_netlink.c   |  4 +++-
>  net/bridge/br_private.h   |  3 ++-
>  net/bridge/br_sysfs_br.c  |  8 +-------
>  4 files changed, 25 insertions(+), 16 deletions(-)
> 

Hi,
One comment below.

[snip]
> @@ -3560,16 +3567,21 @@ static void br_multicast_start_querier(struct net_bridge *br,
>  	rcu_read_unlock();
>  }
>  
> -int br_multicast_toggle(struct net_bridge *br, unsigned long val)
> +int br_multicast_toggle(struct net_bridge *br, unsigned long val,
> +			struct netlink_ext_ack *extack)
>  {
>  	struct net_bridge_port *port;
>  	bool change_snoopers = false;
> +	int err = 0;
>  
>  	spin_lock_bh(&br->multicast_lock);
>  	if (!!br_opt_get(br, BROPT_MULTICAST_ENABLED) == !!val)
>  		goto unlock;
>  
> -	br_mc_disabled_update(br->dev, val);
> +	err = br_mc_disabled_update(br->dev, val, extack);
> +	if (err && err != -EOPNOTSUPP)
> +		goto unlock;
> +
>  	br_opt_toggle(br, BROPT_MULTICAST_ENABLED, !!val);
>  	if (!br_opt_get(br, BROPT_MULTICAST_ENABLED)) {
>  		change_snoopers = true;
> @@ -3607,7 +3619,7 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)
>  			br_multicast_leave_snoopers(br);
>  	}
>  
> -	return 0;
> +	return err;

Here won't you return EOPNOTSUPP even though everything above was successful ?
I mean if br_mc_disabled_update() returns -EOPNOTSUPP it will just be returned
and the caller would think there was an error.

Did you try running the bridge selftests with this patch ?

Thanks,
 Nik

>  }
>  
>  bool br_multicast_enabled(const struct net_device *dev)
> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
> index f2b1343f8332..0456593aceec 100644
> --- a/net/bridge/br_netlink.c
> +++ b/net/bridge/br_netlink.c
> @@ -1293,7 +1293,9 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
>  	if (data[IFLA_BR_MCAST_SNOOPING]) {
>  		u8 mcast_snooping = nla_get_u8(data[IFLA_BR_MCAST_SNOOPING]);
>  
> -		br_multicast_toggle(br, mcast_snooping);
> +		err = br_multicast_toggle(br, mcast_snooping, extack);
> +		if (err)
> +			return err;
>  	}
>  
>  	if (data[IFLA_BR_MCAST_QUERY_USE_IFADDR]) {
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index ecb91e13d777..947c724c26b2 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -812,7 +812,8 @@ void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
>  			struct sk_buff *skb, bool local_rcv, bool local_orig);
>  int br_multicast_set_router(struct net_bridge *br, unsigned long val);
>  int br_multicast_set_port_router(struct net_bridge_port *p, unsigned long val);
> -int br_multicast_toggle(struct net_bridge *br, unsigned long val);
> +int br_multicast_toggle(struct net_bridge *br, unsigned long val,
> +			struct netlink_ext_ack *extack);
>  int br_multicast_set_querier(struct net_bridge *br, unsigned long val);
>  int br_multicast_set_hash_max(struct net_bridge *br, unsigned long val);
>  int br_multicast_set_igmp_version(struct net_bridge *br, unsigned long val);
> diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
> index 072e29840082..381467b691d5 100644
> --- a/net/bridge/br_sysfs_br.c
> +++ b/net/bridge/br_sysfs_br.c
> @@ -409,17 +409,11 @@ static ssize_t multicast_snooping_show(struct device *d,
>  	return sprintf(buf, "%d\n", br_opt_get(br, BROPT_MULTICAST_ENABLED));
>  }
>  
> -static int toggle_multicast(struct net_bridge *br, unsigned long val,
> -			    struct netlink_ext_ack *extack)
> -{
> -	return br_multicast_toggle(br, val);
> -}
> -
>  static ssize_t multicast_snooping_store(struct device *d,
>  					struct device_attribute *attr,
>  					const char *buf, size_t len)
>  {
> -	return store_bridge_parm(d, buf, len, toggle_multicast);
> +	return store_bridge_parm(d, buf, len, br_multicast_toggle);
>  }
>  static DEVICE_ATTR_RW(multicast_snooping);
>  
> 

Re: [PATCH net-next] net: bridge: propagate error code and extack from br_mc_disabled_update

[Vladimir Oltean]

On Wed, Apr 14, 2021 at 05:58:04PM +0300, Nikolay Aleksandrov wrote:
> > @@ -3607,7 +3619,7 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)
> >  			br_multicast_leave_snoopers(br);
> >  	}
> >  
> > -	return 0;
> > +	return err;
> 
> Here won't you return EOPNOTSUPP even though everything above was successful ?
> I mean if br_mc_disabled_update() returns -EOPNOTSUPP it will just be returned
> and the caller would think there was an error.
> 
> Did you try running the bridge selftests with this patch ?
> 
> Thanks,
>  Nik

Thanks, this is a good point. I think I should just do this instead:
	if (err == -EOPNOTSUPP)
		err = 0;
	if (err)
		...

And I haven't run the bridge selftests. You are talking about:
tools/testing/selftests/net/forwarding/bridge_{igmp,mld}.sh
right?

Re: [PATCH net-next] net: bridge: propagate error code and extack from br_mc_disabled_update

[Nikolay Aleksandrov]

On 14/04/2021 18:13, Vladimir Oltean wrote:
> On Wed, Apr 14, 2021 at 05:58:04PM +0300, Nikolay Aleksandrov wrote:
>>> @@ -3607,7 +3619,7 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)
>>>  			br_multicast_leave_snoopers(br);
>>>  	}
>>>  
>>> -	return 0;
>>> +	return err;
>>
>> Here won't you return EOPNOTSUPP even though everything above was successful ?
>> I mean if br_mc_disabled_update() returns -EOPNOTSUPP it will just be returned
>> and the caller would think there was an error.
>>
>> Did you try running the bridge selftests with this patch ?
>>
>> Thanks,
>>  Nik
> 
> Thanks, this is a good point. I think I should just do this instead:
> 	if (err == -EOPNOTSUPP)
> 		err = 0;
> 	if (err)
> 		...
> 
> And I haven't run the bridge selftests. You are talking about:
> tools/testing/selftests/net/forwarding/bridge_{igmp,mld}.sh
> right?
> 

Yeah, but it's nice to run all of the bridge selftests in there, sometimes
unexpected breakages can show up.