| Message ID | 1355141735-19576-1-git-send-email-amwang@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Cong Wang <amwang@redhat.com> Date: Mon, 10 Dec 2012 20:15:35 +0800 > From: Cong Wang <amwang@redhat.com> > > In case of rehashing, introduce a global variable 'br_mdb_rehash_seq' > which gets increased every time when rehashing, and assign > net->dev_base_seq + br_mdb_rehash_seq to cb->seq. > > In theory cb->seq could be wrapped to zero, but this is not > easy to fix, as net->dev_base_seq is not visible inside > br_mdb_rehash(). In practice, this is rare. > > Cc: Herbert Xu <herbert@gondor.apana.org.au> > Cc: Stephen Hemminger <shemminger@vyatta.com> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Thomas Graf <tgraf@suug.ch> > Cc: Jesper Dangaard Brouer <brouer@redhat.com> > Signed-off-by: Cong Wang <amwang@redhat.com> No synchronization at all is applied to this variable, I can't see how this is OK. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Cong Wang <amwang@redhat.com> Date: Tue, 11 Dec 2012 11:49:32 +0800 > On Mon, 2012-12-10 at 13:46 -0500, David Miller wrote: >> From: Cong Wang <amwang@redhat.com> >> Date: Mon, 10 Dec 2012 20:15:35 +0800 >> >> > From: Cong Wang <amwang@redhat.com> >> > >> > In case of rehashing, introduce a global variable 'br_mdb_rehash_seq' >> > which gets increased every time when rehashing, and assign >> > net->dev_base_seq + br_mdb_rehash_seq to cb->seq. >> > >> > In theory cb->seq could be wrapped to zero, but this is not >> > easy to fix, as net->dev_base_seq is not visible inside >> > br_mdb_rehash(). In practice, this is rare. >> > >> > Cc: Herbert Xu <herbert@gondor.apana.org.au> >> > Cc: Stephen Hemminger <shemminger@vyatta.com> >> > Cc: "David S. Miller" <davem@davemloft.net> >> > Cc: Thomas Graf <tgraf@suug.ch> >> > Cc: Jesper Dangaard Brouer <brouer@redhat.com> >> > Signed-off-by: Cong Wang <amwang@redhat.com> >> >> No synchronization at all is applied to this variable, I can't >> see how this is OK. > > br_mdb_rehash() is protected by the multicast spinlock, so increasing > this variable is protected by it, and reading the variable doesn't need > locking. Am I missing anything? Or should we use atomic_t? I missed that locking, ok, looks good. Applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c index edc0d73..ccc43a9 100644 --- a/net/bridge/br_mdb.c +++ b/net/bridge/br_mdb.c @@ -117,10 +117,8 @@ static int br_mdb_dump(struct sk_buff *skb, struct netlink_callback *cb) rcu_read_lock(); - /* TODO: in case of rehashing, we need to check - * consistency for dumping. - */ - cb->seq = net->dev_base_seq; + /* In theory this could be wrapped to 0... */ + cb->seq = net->dev_base_seq + br_mdb_rehash_seq; for_each_netdev_rcu(net, dev) { if (dev->priv_flags & IFF_EBRIDGE) { diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 68e375a..847b98a1 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -37,6 +37,7 @@ rcu_dereference_protected(X, lockdep_is_held(&br->multicast_lock)) static void br_multicast_start_querier(struct net_bridge *br); +unsigned int br_mdb_rehash_seq; #if IS_ENABLED(CONFIG_IPV6) static inline int ipv6_is_transient_multicast(const struct in6_addr *addr) @@ -338,6 +339,7 @@ static int br_mdb_rehash(struct net_bridge_mdb_htable __rcu **mdbp, int max, return err; } + br_mdb_rehash_seq++; call_rcu_bh(&mdb->rcu, br_mdb_free); out: diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index ae0a6ec..f95b766 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -411,6 +411,7 @@ extern int br_ioctl_deviceless_stub(struct net *net, unsigned int cmd, void __us /* br_multicast.c */ #ifdef CONFIG_BRIDGE_IGMP_SNOOPING +extern unsigned int br_mdb_rehash_seq; extern int br_multicast_rcv(struct net_bridge *br, struct net_bridge_port *port, struct sk_buff *skb);