On 08/10/17 12:39, Nikolay Aleksandrov wrote:
> On 08/10/17 08:23, Yotam Gigi wrote:
>> On 10/05/2017 03:09 PM, Nikolay Aleksandrov wrote:
>>> On 05/10/17 13:36, Jiri Pirko wrote:
>>>> From: Yotam Gigi <yot...@mellanox.com>
>>>>
>>>> Every bridge port is in one of four mcast router port states:
>>>> - MDB_RTR_TYPE_PERM - the port is set by the user to be an mrouter port
>>>> regardless of IGMP queries.
>>>> - MDB_RTR_TYPE_DISABLED - the port is set by the user to not be an mrouter
>>>> port regardless of IGMP queries.
>>>> - MDB_RTR_TYPE_TEMP - the port is set by the user to be in mcast router
>>>> learning state, but currently it is not an mrouter port as no IGMP query
>>>> has been received by it for the last multicast_querier_interval.
>>>> - MDB_RTR_TYPE_TEMP_QUERY - the port is set by the user to be in mcast
>>>> router learning state, and currently it is an mrouter port due to an
>>>> IGMP query that has been received by it during the passed
>>>> multicast_querier_interval.
>>> I think you got the last two partially mixed up, MDB_RTR_TYPE_TEMP marks
>>> the port as a router
>>> regardless if there were any igmp queries, while TYPE_TEMP_QUERY means it's
>>> in learning
>>> state. It is the timer (armed vs not) that defines if currently the port is
>>> a router
>>> when one of the TEMP/TEMP_QUERY are set. In the _TEMP case it is always
>>> armed as it
>>> is refreshed by user or igmp queries which was the point of that mode.
>>> So this means in br_multicast_router() just check for the timer_pending or
>>> perm mode.
>>
>>
>> As much as I tried to make this clear, it seems like I failed :)
>>
>> The 4 states I described are currently the "bridged port" states, not the
>> "bridge device" state. A bridged port has these 4 states, all can be set by
>> the
>> user, while the bridge device only uses 3 of these states. This patch makes
>> the
>> bridge device use the 4 states too. I thought it makes sense.
>
> (disclaimer: this is all about bridge ports, not bridge device)
> Right, I'll try to explain again: _TEMP always marks the port as a mcast
> router,
> it does not put it into just learning state waiting for an igmp query and it
> can
> be refreshed by either a query or the user again setting the port in _TEMP.
> While _TEMP_QUERY puts the port in learning state waiting for a query to
> become
> a router, and _TEMP downgrades to _TEMP_QUERY if it expires.
>
> Does that make it clearer ?
>
> so for _TEMP you say:
>>>> - MDB_RTR_TYPE_TEMP - the port is set by the user to be in mcast router
>>>> learning state, but currently it is not an mrouter port as no IGMP query
>>>> has been received by it for the last multicast_querier_interval.
>
> which is not the case, it is always a router when that mode is set on a port.
> Same for _TEMP_QUERY.
Err, sorry by same I meant it is not correct, not that the _TEMP definition is
the same.
Need to get coffee :-)
>
>>
>> The first paragraph describes the current states of a bridged port, and the
>> second one explains the difference between bridged port and bridge device. I
>> will (try to) make it clearer if we agree on resending this patch.
>>
>> Is it clearer now?
>>
>>
>>>
>>> In the port code you have the following transitions:
>>> _TEMP -> TEMP_QUERY (on timer fire or user-set val, port becomes learning
>>> only)
>>> _TEMP -> _TEMP (noop on user refresh or igmp query, timer refreshes)
>>> _TEMP_QUERY -> _TEMP_QUERY (on igmp query the timer is armed, port becomes
>>> router)
>>>
>>> you never have _TEMP_QUERY -> _TEMP, which you're using here to denote the
>>> timer
>>> getting armed and the bridge becoming a router.
>>
>>
>> I am not sure I got this one. I do address that: when an IGMP query is
>> recieved
>> and the current state is _TEMP_QUERY, I arm the timer and set the state to
>> _TEMP. I marked that place on the patch, so you can see below.
>>
>
> Exactly, there is no such transition for the ports. I tried to say that
> you're using
> the router type to distinguish between when a query is received and it is
> just learning.
> I get that you need to do so, but that deviates from how ports are handled,
> thus I
> suggested to use the timer state instead and drop the _TEMP for bridge device
> altogether.
> If it's possible then the patch will be much simpler and you will not need
> the hacks
> to hide the state from user-space which is the part I really don't like.
>
>>
>>>
>>>> The bridge device (brX) itself can also be configured by the user to be
>>>> either fixed, disabled or learning mrouter port states, but currently there
>>>> is no distinction between the MDB_RTR_TYPE_TEMP_QUERY and MDB_RTR_TYPE_TEMP
>>>> in the bridge internal state. Due to that, when an IGMP query is received,
>>>> it is not straightforward to tell whether it changes the bridge device
>>>> mrouter port status or not.
>>> But before this patch the bridge device could not get that set.
>>>
>>>> Further patches in this patch-set will introduce notifications upon the
>>>> bridge device mrouter port state. In order to prevent resending bridge
>>>> mrouter notification when it is not needed, such distinction is necessary.
>>>>
>>> Granted the bridge device hasn't got a way to clearly distinguish the
>>> transitions
>>> without the chance for a race and if using the timer one could get an
>>> unnecessary
>>
>> Is there a race condition?
>>
>
> With this state - no, if you try to use the timer state though there might be
> an extra notification as I've explained below, that's why I asked if it would
> be
> a problem. I think it is worth looking into using the timer state because it
> will
> remove a lot of the hacks for hiding the state needed in this patch.
>
>>> notification but that seems like a corner case when the timer fires exactly
>>> at the
>>> same time as the igmp query is received. Can't it be handled by just
>>> checking if
>>> the new state is different in the notification receiver ?
>>> If it can't and is a problem then I'd prefer to add a new boolean to denote
>>> that
>>> router on/off transition rather than doing this.
>>>
>>>> Hence, add the distinction between MDB_RTR_TYPE_TEMP and
>>>> MDB_RTR_TYPE_TEMP_QUERY states for the bridge device, similarly to any
>>>> other bridge port.
>>>>
>>> This does not add proper MDB_RTR_TYPE_TEMP support for the bridge device
>>> but seems to abuse it to distinguish the timer state, and changes
>>> the meaning of MDB_RTR_TYPE_TEMP. Can't you just use the timer instead ?
>>> I think it will simplify the set and avoid all of this.
>>>
>>>> In order to not break the current kernel-user API, don't propagate the new
>>>> state to the user and use it only in the bridge internal state. Thus, if
>>>> the user reads (either via sysfs or netlink) the bridge device mrouter
>>>> state, he will get the MDB_RTR_TYPE_TEMP_QUERY state even if the current
>>>> bridge state is MDB_RTR_TYPE_TEMP.
>>>>
>>>> Signed-off-by: Yotam Gigi <yot...@mellanox.com>
>>>> Reviewed-by: Nogah Frankel <nog...@mellanox.com>
>>>> Signed-off-by: Jiri Pirko <j...@mellanox.com>
>>>> ---
>>>> net/bridge/br_multicast.c | 25 +++++++++++++++++++++----
>>>> net/bridge/br_netlink.c | 3 ++-
>>>> net/bridge/br_private.h | 13 ++++++++++---
>>>> net/bridge/br_sysfs_br.c | 3 ++-
>>>> 4 files changed, 35 insertions(+), 9 deletions(-)
>>>>
>>>> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
>>>> index 8dc5c8d..b86307b 100644
>>>> --- a/net/bridge/br_multicast.c
>>>> +++ b/net/bridge/br_multicast.c
>>>> @@ -861,6 +861,17 @@ static void br_multicast_router_expired(unsigned long
>>>> data)
>>>>
>>>> static void br_multicast_local_router_expired(unsigned long data)
>>>> {
>>>> + struct net_bridge *br = (struct net_bridge *) data;
>>>> +
>>>> + spin_lock(&br->multicast_lock);
>>>> + if (br->multicast_router == MDB_RTR_TYPE_DISABLED ||
>>>> + br->multicast_router == MDB_RTR_TYPE_PERM ||
>>>> + timer_pending(&br->multicast_router_timer))
>>>> + goto out;
>>>> +
>>>> + br->multicast_router = MDB_RTR_TYPE_TEMP_QUERY;
>>>> +out:
>>>> + spin_unlock(&br->multicast_lock);
>>>> }
>>>>
>>>> static void br_multicast_querier_expired(struct net_bridge *br,
>>>> @@ -1364,9 +1375,12 @@ static void br_multicast_mark_router(struct
>>>> net_bridge *br,
>>>> unsigned long now = jiffies;
>>>>
>>>> if (!port) {
>>>> - if (br->multicast_router == MDB_RTR_TYPE_TEMP_QUERY)
>>>> + if (br->multicast_router == MDB_RTR_TYPE_TEMP_QUERY ||
>>>> + br->multicast_router == MDB_RTR_TYPE_TEMP) {
>>>> mod_timer(&br->multicast_router_timer,
>>>> now + br->multicast_querier_interval);
>>>> + br->multicast_router = MDB_RTR_TYPE_TEMP;
>>>> + }
>>
>>
>> These are the transitions:
>> _TEMP -> _TEMP_QUERY
>> _TEMP_QUERY -> _TEMP_QUERY
>
> You clearly always set multicast_router to _TEMP, where did you see a
> transition
> _TEMP_QUERY -> _TEMP_QUERY or _TEMP -> _TEMP_QUERY ?
> All transitions are -> _TEMP, because you use it to differentiate between
> learning
> state and when a query was received. Maybe we have different definition for
> a transition :-)
>
>>
>> In both transitions the timer is armed.
>>
>>
>>>> return;
>>>> }
>>>>
>>>> @@ -1952,7 +1966,7 @@ void br_multicast_init(struct net_bridge *br)
>>>>
>>>> spin_lock_init(&br->multicast_lock);
>>>> setup_timer(&br->multicast_router_timer,
>>>> - br_multicast_local_router_expired, 0);
>>>> + br_multicast_local_router_expired, (unsigned long)br);
>>>> setup_timer(&br->ip4_other_query.timer,
>>>> br_ip4_multicast_querier_expired, (unsigned long)br);
>>>> setup_timer(&br->ip4_own_query.timer, br_ip4_multicast_query_expired,
>>>> @@ -2043,11 +2057,14 @@ int br_multicast_set_router(struct net_bridge *br,
>>>> unsigned long val)
>>>> case MDB_RTR_TYPE_DISABLED:
>>>> case MDB_RTR_TYPE_PERM:
>>>> del_timer(&br->multicast_router_timer);
>>>> - /* fall through */
>>>> - case MDB_RTR_TYPE_TEMP_QUERY:
>>>> br->multicast_router = val;
>>>> err = 0;
>>>> break;
>>>> + case MDB_RTR_TYPE_TEMP_QUERY:
>>>> + if (br->multicast_router != MDB_RTR_TYPE_TEMP)
>>>> + br->multicast_router = val;
>>>> + err = 0;
>>>> + break;
>>>> }
>>>>
>>>> spin_unlock_bh(&br->multicast_lock);
>>>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>>>> index dea88a2..cee5016 100644
>>>> --- a/net/bridge/br_netlink.c
>>>> +++ b/net/bridge/br_netlink.c
>>>> @@ -1357,7 +1357,8 @@ static int br_fill_info(struct sk_buff *skb, const
>>>> struct net_device *brdev)
>>>> return -EMSGSIZE;
>>>> #endif
>>>> #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
>>>> - if (nla_put_u8(skb, IFLA_BR_MCAST_ROUTER, br->multicast_router) ||
>>>> + if (nla_put_u8(skb, IFLA_BR_MCAST_ROUTER,
>>>> + br_multicast_router_translate(br->multicast_router)) ||
>>>> nla_put_u8(skb, IFLA_BR_MCAST_SNOOPING, !br->multicast_disabled) ||
>>>> nla_put_u8(skb, IFLA_BR_MCAST_QUERY_USE_IFADDR,
>>>> br->multicast_query_use_ifaddr) ||
>>>> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
>>>> index ab4df24..e6e3fec 100644
>>>> --- a/net/bridge/br_private.h
>>>> +++ b/net/bridge/br_private.h
>>>> @@ -649,9 +649,8 @@ void br_multicast_get_stats(const struct net_bridge
>>>> *br,
>>>>
>>>> static inline bool br_multicast_is_router(struct net_bridge *br)
>>>> {
>>>> - return br->multicast_router == 2 ||
>>>> - (br->multicast_router == 1 &&
>>>> - timer_pending(&br->multicast_router_timer));
>>>> + return br->multicast_router == MDB_RTR_TYPE_PERM ||
>>>> + br->multicast_router == MDB_RTR_TYPE_TEMP;
>>>> }
>>>>
>>>> static inline bool
>>>> @@ -790,6 +789,14 @@ static inline int br_multicast_igmp_type(const struct
>>>> sk_buff *skb)
>>>> }
>>>> #endif
>>>>
>>>> +static inline unsigned char
>>> u8
>>>
>>>> +br_multicast_router_translate(unsigned char multicast_router)
>>> u8, if need be change the type of the struct member
>>
>>
>> Sorry, didn't quite get that. Currently, both the bridge_port and bridge have
>> the multicast_router field, and in both cases it is of type unsigned char. Do
>> you suggest to change both to be "u8"?
>>
>
> Right, and this is unnecessarily long and requires to be broken ugly like
> that with
> the type above and name below. So I suggested to use u8 to avoid that.
>
>>
>>>
>>>> +{
>>>> + if (multicast_router == MDB_RTR_TYPE_TEMP)
>>>> + return MDB_RTR_TYPE_TEMP_QUERY;
>>>> + return multicast_router;
>>>> +}
>>>> +
>>>> /* br_vlan.c */
>>>> #ifdef CONFIG_BRIDGE_VLAN_FILTERING
>>>> bool br_allowed_ingress(const struct net_bridge *br,
>>>> diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
>>>> index 723f25e..9b9c597 100644
>>>> --- a/net/bridge/br_sysfs_br.c
>>>> +++ b/net/bridge/br_sysfs_br.c
>>>> @@ -340,7 +340,8 @@ static ssize_t multicast_router_show(struct device *d,
>>>> struct device_attribute *attr, char *buf)
>>>> {
>>>> struct net_bridge *br = to_bridge(d);
>>>> - return sprintf(buf, "%d\n", br->multicast_router);
>>>> + return sprintf(buf, "%d\n",
>>>> + br_multicast_router_translate(br->multicast_router));
>>>> }
>>>>
>>>> static ssize_t multicast_router_store(struct device *d,
>>>>
>>
>
