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.
>
> 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,
>>>
>
