| Message ID | 20190730112100.18156-1-nikolay@cumulusnetworks.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net] net: bridge: mcast: don't delete permanent entries when fast leave is enabled | expand |
On 7/30/19 5:21 AM, Nikolay Aleksandrov wrote: > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c > index 3d8deac2353d..f8cac3702712 100644 > --- a/net/bridge/br_multicast.c > +++ b/net/bridge/br_multicast.c > @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br, > if (!br_port_group_equal(p, port, src)) > continue; > > + if (p->flags & MDB_PG_FLAGS_PERMANENT) > + break; > + > rcu_assign_pointer(*pp, p->next); > hlist_del_init(&p->mglist); > del_timer(&p->timer); Why 'break' and not 'continue' like you have with if (!br_port_group_equal(p, port, src))
On 30/07/2019 16:58, David Ahern wrote: > On 7/30/19 5:21 AM, Nikolay Aleksandrov wrote: >> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c >> index 3d8deac2353d..f8cac3702712 100644 >> --- a/net/bridge/br_multicast.c >> +++ b/net/bridge/br_multicast.c >> @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br, >> if (!br_port_group_equal(p, port, src)) >> continue; >> >> + if (p->flags & MDB_PG_FLAGS_PERMANENT) >> + break; >> + >> rcu_assign_pointer(*pp, p->next); >> hlist_del_init(&p->mglist); >> del_timer(&p->timer); > > Why 'break' and not 'continue' like you have with > if (!br_port_group_equal(p, port, src)) > Because we'll hit the goto out after this hunk always, no point in continuing if we matched a group and it's permanent, the break might as well be a goto out.
From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Date: Tue, 30 Jul 2019 14:21:00 +0300 > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c > index 3d8deac2353d..f8cac3702712 100644 > --- a/net/bridge/br_multicast.c > +++ b/net/bridge/br_multicast.c > @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br, > if (!br_port_group_equal(p, port, src)) > continue; > > + if (p->flags & MDB_PG_FLAGS_PERMANENT) > + break; > + Like David, I also don't understand why this can be a break. Is it because permanent entries are always the last on the list? Why will there be no other entries that might need to be processed on the list?
On 30/07/2019 20:18, David Miller wrote: > From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> > Date: Tue, 30 Jul 2019 14:21:00 +0300 > >> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c >> index 3d8deac2353d..f8cac3702712 100644 >> --- a/net/bridge/br_multicast.c >> +++ b/net/bridge/br_multicast.c >> @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br, >> if (!br_port_group_equal(p, port, src)) >> continue; >> >> + if (p->flags & MDB_PG_FLAGS_PERMANENT) >> + break; >> + > > Like David, I also don't understand why this can be a break. Is it because > permanent entries are always the last on the list? Why will there be no > other entries that might need to be processed on the list? > The reason is that only one port can match. See the first clause of br_port_group_equal, that port can participate only once. We could easily add a break statement in the end when a match is found and it will be correct. Even in the presence of MULTICAST_TO_UNICAST flag, the port must match and can be added only once.
On 30/07/2019 20:21, Nikolay Aleksandrov wrote: > On 30/07/2019 20:18, David Miller wrote: >> From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> >> Date: Tue, 30 Jul 2019 14:21:00 +0300 >> >>> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c >>> index 3d8deac2353d..f8cac3702712 100644 >>> --- a/net/bridge/br_multicast.c >>> +++ b/net/bridge/br_multicast.c >>> @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br, >>> if (!br_port_group_equal(p, port, src)) >>> continue; >>> >>> + if (p->flags & MDB_PG_FLAGS_PERMANENT) >>> + break; >>> + >> >> Like David, I also don't understand why this can be a break. Is it because >> permanent entries are always the last on the list? Why will there be no >> other entries that might need to be processed on the list? >> > > The reason is that only one port can match. See the first clause of br_port_group_equal, > that port can participate only once. We could easily add a break statement in the end > when a match is found and it will be correct. Even in the presence of MULTICAST_TO_UNICAST > flag, the port must match and can be added only once. > Like I wrote in the patch I plan to re-work that code in net-next to remove the duplication and make it more understandable to avoid such confusions. This code will be functionally equivalent if I put continue there, we'll just walk over all of them even after a match or permanent are found. There can only be one match though as I said, so walking the rest of the ports is a waste.
From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Date: Tue, 30 Jul 2019 14:21:00 +0300 > When permanent entries were introduced by the commit below, they were > exempt from timing out and thus igmp leave wouldn't affect them unless > fast leave was enabled on the port which was added before permanent > entries existed. It shouldn't matter if fast leave is enabled or not > if the user added a permanent entry it shouldn't be deleted on igmp > leave. ... > Fixes: ccb1c31a7a87 ("bridge: add flags to distinguish permanent mdb entires") > Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Applied and queued up for -stable.
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 3d8deac2353d..f8cac3702712 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br, if (!br_port_group_equal(p, port, src)) continue; + if (p->flags & MDB_PG_FLAGS_PERMANENT) + break; + rcu_assign_pointer(*pp, p->next); hlist_del_init(&p->mglist); del_timer(&p->timer);
When permanent entries were introduced by the commit below, they were exempt from timing out and thus igmp leave wouldn't affect them unless fast leave was enabled on the port which was added before permanent entries existed. It shouldn't matter if fast leave is enabled or not if the user added a permanent entry it shouldn't be deleted on igmp leave. Before: $ echo 1 > /sys/class/net/eth4/brport/multicast_fast_leave $ bridge mdb add dev br0 port eth4 grp 229.1.1.1 permanent $ bridge mdb show dev br0 port eth4 grp 229.1.1.1 permanent < join and leave 229.1.1.1 on eth4 > $ bridge mdb show $ After: $ echo 1 > /sys/class/net/eth4/brport/multicast_fast_leave $ bridge mdb add dev br0 port eth4 grp 229.1.1.1 permanent $ bridge mdb show dev br0 port eth4 grp 229.1.1.1 permanent < join and leave 229.1.1.1 on eth4 > $ bridge mdb show dev br0 port eth4 grp 229.1.1.1 permanent Fixes: ccb1c31a7a87 ("bridge: add flags to distinguish permanent mdb entires") Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> --- I'll re-work this code in net-next as there's a lot of duplication. net/bridge/br_multicast.c | 3 +++ 1 file changed, 3 insertions(+)