Merge branch 'bridge-fdbs-bitops'

Nikolay Aleksandrov says:

====================
net: bridge: convert fdbs to use bitops

We'd like to have a well-defined behaviour when changing fdb flags. The
problem is that we've added new fields which are changed from all
contexts without any locking. We are aware of the bit test/change races
and these are fine (we can remove them later), but it is considered
undefined behaviour to change bitfields from multiple threads and also
on some architectures that can result in unexpected results,
specifically when all fields between the changed ones are also
bitfields. The conversion to bitops shows the intent clearly and
makes them use functions with well-defined behaviour in such cases.
There is no overhead for the fast-path, the bit changing functions are
used only in special cases when learning and in the slow path.
In addition this conversion allows us to simplify fdb flag handling and
avoid bugs for future bits (e.g. a forgetting to clear the new bit when
allocating a new fdb). All bridge selftests passed, also tried all of the
converted bits manually in a VM.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 85 insertions, 79 deletions

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index b1d3248c0252..f244f2ac7156 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -75,8 +75,9 @@ static inline unsigned long hold_time(const struct net_bridge *br)
 static inline int has_expired(const struct net_bridge *br,
 				  const struct net_bridge_fdb_entry *fdb)
 {
-	return !fdb->is_static && !fdb->added_by_external_learn &&
-		time_before_eq(fdb->updated + hold_time(br), jiffies);
+	return !test_bit(BR_FDB_STATIC, &fdb->flags) &&
+	       !test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags) &&
+	       time_before_eq(fdb->updated + hold_time(br), jiffies);
 }
 
 static void fdb_rcu_free(struct rcu_head *head)
@@ -197,7 +198,7 @@ static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f,
 {
 	trace_fdb_delete(br, f);
 
-	if (f->is_static)
+	if (test_bit(BR_FDB_STATIC, &f->flags))
 		fdb_del_hw_addr(br, f->key.addr.addr);
 
 	hlist_del_init_rcu(&f->fdb_node);
@@ -224,7 +225,7 @@ static void fdb_delete_local(struct net_bridge *br,
 		if (op != p && ether_addr_equal(op->dev->dev_addr, addr) &&
 		    (!vid || br_vlan_find(vg, vid))) {
 			f->dst = op;
-			f->added_by_user = 0;
+			clear_bit(BR_FDB_ADDED_BY_USER, &f->flags);
 			return;
 		}
 	}
@@ -235,7 +236,7 @@ static void fdb_delete_local(struct net_bridge *br,
 	if (p && ether_addr_equal(br->dev->dev_addr, addr) &&
 	    (!vid || (v && br_vlan_should_use(v)))) {
 		f->dst = NULL;
-		f->added_by_user = 0;
+		clear_bit(BR_FDB_ADDED_BY_USER, &f->flags);
 		return;
 	}
 
@@ -250,7 +251,8 @@ void br_fdb_find_delete_local(struct net_bridge *br,
 
 	spin_lock_bh(&br->hash_lock);
 	f = br_fdb_find(br, addr, vid);
-	if (f && f->is_local && !f->added_by_user && f->dst == p)
+	if (f && test_bit(BR_FDB_LOCAL, &f->flags) &&
+	    !test_bit(BR_FDB_ADDED_BY_USER, &f->flags) && f->dst == p)
 		fdb_delete_local(br, p, f);
 	spin_unlock_bh(&br->hash_lock);
 }
@@ -265,7 +267,8 @@ void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
 	spin_lock_bh(&br->hash_lock);
 	vg = nbp_vlan_group(p);
 	hlist_for_each_entry(f, &br->fdb_list, fdb_node) {
-		if (f->dst == p && f->is_local && !f->added_by_user) {
+		if (f->dst == p && test_bit(BR_FDB_LOCAL, &f->flags) &&
+		    !test_bit(BR_FDB_ADDED_BY_USER, &f->flags)) {
 			/* delete old one */
 			fdb_delete_local(br, p, f);
 
@@ -306,7 +309,8 @@ void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
 
 	/* If old entry was unassociated with any port, then delete it. */
 	f = br_fdb_find(br, br->dev->dev_addr, 0);
-	if (f && f->is_local && !f->dst && !f->added_by_user)
+	if (f && test_bit(BR_FDB_LOCAL, &f->flags) &&
+	    !f->dst && !test_bit(BR_FDB_ADDED_BY_USER, &f->flags))
 		fdb_delete_local(br, NULL, f);
 
 	fdb_insert(br, NULL, newaddr, 0);
@@ -321,7 +325,8 @@ void br_fdb_change_mac_address(struct net_bridge *br, const u8 *newaddr)
 		if (!br_vlan_should_use(v))
 			continue;
 		f = br_fdb_find(br, br->dev->dev_addr, v->vid);
-		if (f && f->is_local && !f->dst && !f->added_by_user)
+		if (f && test_bit(BR_FDB_LOCAL, &f->flags) &&
+		    !f->dst && !test_bit(BR_FDB_ADDED_BY_USER, &f->flags))
 			fdb_delete_local(br, NULL, f);
 		fdb_insert(br, NULL, newaddr, v->vid);
 	}
@@ -346,7 +351,8 @@ void br_fdb_cleanup(struct work_struct *work)
 	hlist_for_each_entry_rcu(f, &br->fdb_list, fdb_node) {
 		unsigned long this_timer;
 
-		if (f->is_static || f->added_by_external_learn)
+		if (test_bit(BR_FDB_STATIC, &f->flags) ||
+		    test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &f->flags))
 			continue;
 		this_timer = f->updated + delay;
 		if (time_after(this_timer, now)) {
@@ -373,7 +379,7 @@ void br_fdb_flush(struct net_bridge *br)
 
 	spin_lock_bh(&br->hash_lock);
 	hlist_for_each_entry_safe(f, tmp, &br->fdb_list, fdb_node) {
-		if (!f->is_static)
+		if (!test_bit(BR_FDB_STATIC, &f->flags))
 			fdb_delete(br, f, true);
 	}
 	spin_unlock_bh(&br->hash_lock);
@@ -397,10 +403,11 @@ void br_fdb_delete_by_port(struct net_bridge *br,
 			continue;
 
 		if (!do_all)
-			if (f->is_static || (vid && f->key.vlan_id != vid))
+			if (test_bit(BR_FDB_STATIC, &f->flags) ||
+			    (vid && f->key.vlan_id != vid))
 				continue;
 
-		if (f->is_local)
+		if (test_bit(BR_FDB_LOCAL, &f->flags))
 			fdb_delete_local(br, p, f);
 		else
 			fdb_delete(br, f, true);
@@ -469,8 +476,8 @@ int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 		fe->port_no = f->dst->port_no;
 		fe->port_hi = f->dst->port_no >> 8;
 
-		fe->is_local = f->is_local;
-		if (!f->is_static)
+		fe->is_local = test_bit(BR_FDB_LOCAL, &f->flags);
+		if (!test_bit(BR_FDB_STATIC, &f->flags))
 			fe->ageing_timer_value = jiffies_delta_to_clock_t(jiffies - f->updated);
 		++fe;
 		++num;
@@ -484,8 +491,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
 					       struct net_bridge_port *source,
 					       const unsigned char *addr,
 					       __u16 vid,
-					       unsigned char is_local,
-					       unsigned char is_static)
+					       unsigned long flags)
 {
 	struct net_bridge_fdb_entry *fdb;
 
@@ -494,12 +500,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
 		memcpy(fdb->key.addr.addr, addr, ETH_ALEN);
 		fdb->dst = source;
 		fdb->key.vlan_id = vid;
-		fdb->is_local = is_local;
-		fdb->is_static = is_static;
-		fdb->added_by_user = 0;
-		fdb->added_by_external_learn = 0;
-		fdb->offloaded = 0;
-		fdb->is_sticky = 0;
+		fdb->flags = flags;
 		fdb->updated = fdb->used = jiffies;
 		if (rhashtable_lookup_insert_fast(&br->fdb_hash_tbl,
 						  &fdb->rhnode,
@@ -526,14 +527,15 @@ static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 		/* it is okay to have multiple ports with same
 		 * address, just use the first one.
 		 */
-		if (fdb->is_local)
+		if (test_bit(BR_FDB_LOCAL, &fdb->flags))
 			return 0;
 		br_warn(br, "adding interface %s with same address as a received packet (addr:%pM, vlan:%u)\n",
 		       source ? source->dev->name : br->dev->name, addr, vid);
 		fdb_delete(br, fdb, true);
 	}
 
-	fdb = fdb_create(br, source, addr, vid, 1, 1);
+	fdb = fdb_create(br, source, addr, vid,
+			 BIT(BR_FDB_LOCAL) | BIT(BR_FDB_STATIC));
 	if (!fdb)
 		return -ENOMEM;
 
@@ -572,7 +574,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 	fdb = fdb_find_rcu(&br->fdb_hash_tbl, addr, vid);
 	if (likely(fdb)) {
 		/* attempt to update an entry for a local interface */
-		if (unlikely(fdb->is_local)) {
+		if (unlikely(test_bit(BR_FDB_LOCAL, &fdb->flags))) {
 			if (net_ratelimit())
 				br_warn(br, "received packet on %s with own address as source address (addr:%pM, vlan:%u)\n",
 					source->dev->name, addr, vid);
@@ -580,17 +582,18 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 			unsigned long now = jiffies;
 
 			/* fastpath: update of existing entry */
-			if (unlikely(source != fdb->dst && !fdb->is_sticky)) {
+			if (unlikely(source != fdb->dst &&
+				     !test_bit(BR_FDB_STICKY, &fdb->flags))) {
 				fdb->dst = source;
 				fdb_modified = true;
 				/* Take over HW learned entry */
-				if (unlikely(fdb->added_by_external_learn))
-					fdb->added_by_external_learn = 0;
+				test_and_clear_bit(BR_FDB_ADDED_BY_EXT_LEARN,
+						   &fdb->flags);
 			}
 			if (now != fdb->updated)
 				fdb->updated = now;
 			if (unlikely(added_by_user))
-				fdb->added_by_user = 1;
+				set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
 			if (unlikely(fdb_modified)) {
 				trace_br_fdb_update(br, source, addr, vid, added_by_user);
 				fdb_notify(br, fdb, RTM_NEWNEIGH, true);
@@ -598,10 +601,10 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 		}
 	} else {
 		spin_lock(&br->hash_lock);
-		fdb = fdb_create(br, source, addr, vid, 0, 0);
+		fdb = fdb_create(br, source, addr, vid, 0);
 		if (fdb) {
 			if (unlikely(added_by_user))
-				fdb->added_by_user = 1;
+				set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
 			trace_br_fdb_update(br, source, addr, vid,
 					    added_by_user);
 			fdb_notify(br, fdb, RTM_NEWNEIGH, true);
@@ -616,9 +619,9 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
 static int fdb_to_nud(const struct net_bridge *br,
 		      const struct net_bridge_fdb_entry *fdb)
 {
-	if (fdb->is_local)
+	if (test_bit(BR_FDB_LOCAL, &fdb->flags))
 		return NUD_PERMANENT;
-	else if (fdb->is_static)
+	else if (test_bit(BR_FDB_STATIC, &fdb->flags))
 		return NUD_NOARP;
 	else if (has_expired(br, fdb))
 		return NUD_STALE;
@@ -648,11 +651,11 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
 	ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
 	ndm->ndm_state   = fdb_to_nud(br, fdb);
 
-	if (fdb->offloaded)
+	if (test_bit(BR_FDB_OFFLOADED, &fdb->flags))
 		ndm->ndm_flags |= NTF_OFFLOADED;
-	if (fdb->added_by_external_learn)
+	if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags))
 		ndm->ndm_flags |= NTF_EXT_LEARNED;
-	if (fdb->is_sticky)
+	if (test_bit(BR_FDB_STICKY, &fdb->flags))
 		ndm->ndm_flags |= NTF_STICKY;
 
 	if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
@@ -799,7 +802,7 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 			 const u8 *addr, u16 state, u16 flags, u16 vid,
 			 u8 ndm_flags)
 {
-	u8 is_sticky = !!(ndm_flags & NTF_STICKY);
+	bool is_sticky = !!(ndm_flags & NTF_STICKY);
 	struct net_bridge_fdb_entry *fdb;
 	bool modified = false;
 
@@ -823,7 +826,7 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 		if (!(flags & NLM_F_CREATE))
 			return -ENOENT;
 
-		fdb = fdb_create(br, source, addr, vid, 0, 0);
+		fdb = fdb_create(br, source, addr, vid, 0);
 		if (!fdb)
 			return -ENOMEM;
 
@@ -840,34 +843,28 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 
 	if (fdb_to_nud(br, fdb) != state) {
 		if (state & NUD_PERMANENT) {
-			fdb->is_local = 1;
-			if (!fdb->is_static) {
-				fdb->is_static = 1;
+			set_bit(BR_FDB_LOCAL, &fdb->flags);
+			if (!test_and_set_bit(BR_FDB_STATIC, &fdb->flags))
 				fdb_add_hw_addr(br, addr);
-			}
 		} else if (state & NUD_NOARP) {
-			fdb->is_local = 0;
-			if (!fdb->is_static) {
-				fdb->is_static = 1;
+			clear_bit(BR_FDB_LOCAL, &fdb->flags);
+			if (!test_and_set_bit(BR_FDB_STATIC, &fdb->flags))
 				fdb_add_hw_addr(br, addr);
-			}
 		} else {
-			fdb->is_local = 0;
-			if (fdb->is_static) {
-				fdb->is_static = 0;
+			clear_bit(BR_FDB_LOCAL, &fdb->flags);
+			if (test_and_clear_bit(BR_FDB_STATIC, &fdb->flags))
 				fdb_del_hw_addr(br, addr);
-			}
 		}
 
 		modified = true;
 	}
 
-	if (is_sticky != fdb->is_sticky) {
-		fdb->is_sticky = is_sticky;
+	if (is_sticky != test_bit(BR_FDB_STICKY, &fdb->flags)) {
+		change_bit(BR_FDB_STICKY, &fdb->flags);
 		modified = true;
 	}
 
-	fdb->added_by_user = 1;
+	set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
 
 	fdb->used = jiffies;
 	if (modified) {
@@ -1064,7 +1061,7 @@ int br_fdb_sync_static(struct net_bridge *br, struct net_bridge_port *p)
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(f, &br->fdb_list, fdb_node) {
 		/* We only care for static entries */
-		if (!f->is_static)
+		if (!test_bit(BR_FDB_STATIC, &f->flags))
 			continue;
 		err = dev_uc_add(p->dev, f->key.addr.addr);
 		if (err)
@@ -1078,7 +1075,7 @@ done:
 rollback:
 	hlist_for_each_entry_rcu(tmp, &br->fdb_list, fdb_node) {
 		/* We only care for static entries */
-		if (!tmp->is_static)
+		if (!test_bit(BR_FDB_STATIC, &tmp->flags))
 			continue;
 		if (tmp == f)
 			break;
@@ -1097,7 +1094,7 @@ void br_fdb_unsync_static(struct net_bridge *br, struct net_bridge_port *p)
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(f, &br->fdb_list, fdb_node) {
 		/* We only care for static entries */
-		if (!f->is_static)
+		if (!test_bit(BR_FDB_STATIC, &f->flags))
 			continue;
 
 		dev_uc_del(p->dev, f->key.addr.addr);
@@ -1119,14 +1116,14 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
 
 	fdb = br_fdb_find(br, addr, vid);
 	if (!fdb) {
-		fdb = fdb_create(br, p, addr, vid, 0, 0);
+		fdb = fdb_create(br, p, addr, vid, 0);
 		if (!fdb) {
 			err = -ENOMEM;
 			goto err_unlock;
 		}
 		if (swdev_notify)
-			fdb->added_by_user = 1;
-		fdb->added_by_external_learn = 1;
+			set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
+		set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags);
 		fdb_notify(br, fdb, RTM_NEWNEIGH, swdev_notify);
 	} else {
 		fdb->updated = jiffies;
@@ -1136,17 +1133,17 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
 			modified = true;
 		}
 
-		if (fdb->added_by_external_learn) {
+		if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) {
 			/* Refresh entry */
 			fdb->used = jiffies;
-		} else if (!fdb->added_by_user) {
+		} else if (!test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags)) {
 			/* Take over SW learned entry */
-			fdb->added_by_external_learn = 1;
+			set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags);
 			modified = true;
 		}
 
 		if (swdev_notify)
-			fdb->added_by_user = 1;
+			set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
 
 		if (modified)
 			fdb_notify(br, fdb, RTM_NEWNEIGH, swdev_notify);
@@ -1168,7 +1165,7 @@ int br_fdb_external_learn_del(struct net_bridge *br, struct net_bridge_port *p,
 	spin_lock_bh(&br->hash_lock);
 
 	fdb = br_fdb_find(br, addr, vid);
-	if (fdb && fdb->added_by_external_learn)
+	if (fdb && test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags))
 		fdb_delete(br, fdb, swdev_notify);
 	else
 		err = -ENOENT;
@@ -1186,8 +1183,8 @@ void br_fdb_offloaded_set(struct net_bridge *br, struct net_bridge_port *p,
 	spin_lock_bh(&br->hash_lock);
 
 	fdb = br_fdb_find(br, addr, vid);
-	if (fdb)
-		fdb->offloaded = offloaded;
+	if (fdb && offloaded != test_bit(BR_FDB_OFFLOADED, &fdb->flags))
+		change_bit(BR_FDB_OFFLOADED, &fdb->flags);
 
 	spin_unlock_bh(&br->hash_lock);
 }
@@ -1206,7 +1203,7 @@ void br_fdb_clear_offload(const struct net_device *dev, u16 vid)
 	spin_lock_bh(&p->br->hash_lock);
 	hlist_for_each_entry(f, &p->br->fdb_list, fdb_node) {
 		if (f->dst == p && f->key.vlan_id == vid)
-			f->offloaded = 0;
+			clear_bit(BR_FDB_OFFLOADED, &f->flags);
 	}
 	spin_unlock_bh(&p->br->hash_lock);
 }
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 09b1dd8cd853..7f5f646dba6e 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -151,7 +151,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 	if (dst) {
 		unsigned long now = jiffies;
 
-		if (dst->is_local)
+		if (test_bit(BR_FDB_LOCAL, &dst->flags))
 			return br_pass_frame_up(skb);
 
 		if (now != dst->used)
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index ce2ab14ee605..f4754bf7f4bd 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -172,6 +172,16 @@ struct net_bridge_vlan_group {
 	u16				pvid;
 };
 
+/* bridge fdb flags */
+enum {
+	BR_FDB_LOCAL,
+	BR_FDB_STATIC,
+	BR_FDB_STICKY,
+	BR_FDB_ADDED_BY_USER,
+	BR_FDB_ADDED_BY_EXT_LEARN,
+	BR_FDB_OFFLOADED,
+};
+
 struct net_bridge_fdb_key {
 	mac_addr addr;
 	u16 vlan_id;
@@ -183,12 +193,7 @@ struct net_bridge_fdb_entry {
 
 	struct net_bridge_fdb_key	key;
 	struct hlist_node		fdb_node;
-	unsigned char			is_local:1,
-					is_static:1,
-					is_sticky:1,
-					added_by_user:1,
-					added_by_external_learn:1,
-					offloaded:1;
+	unsigned long			flags;
 
 	/* write-heavy members should not affect lookups */
 	unsigned long			updated ____cacheline_aligned_in_smp;
diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c
index 921310d3cbae..015209bf44aa 100644
--- a/net/bridge/br_switchdev.c
+++ b/net/bridge/br_switchdev.c
@@ -129,15 +129,19 @@ br_switchdev_fdb_notify(const struct net_bridge_fdb_entry *fdb, int type)
 		br_switchdev_fdb_call_notifiers(false, fdb->key.addr.addr,
 						fdb->key.vlan_id,
 						fdb->dst->dev,
-						fdb->added_by_user,
-						fdb->offloaded);
+						test_bit(BR_FDB_ADDED_BY_USER,
+							 &fdb->flags),
+						test_bit(BR_FDB_OFFLOADED,
+							 &fdb->flags));
 		break;
 	case RTM_NEWNEIGH:
 		br_switchdev_fdb_call_notifiers(true, fdb->key.addr.addr,
 						fdb->key.vlan_id,
 						fdb->dst->dev,
-						fdb->added_by_user,
-						fdb->offloaded);
+						test_bit(BR_FDB_ADDED_BY_USER,
+							 &fdb->flags),
+						test_bit(BR_FDB_OFFLOADED,
+							 &fdb->flags));
 		break;
 	}
 }