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authorVladimir Oltean <vladimir.oltean@nxp.com>2021-06-29 17:06:44 +0300
committerDavid S. Miller <davem@davemloft.net>2021-06-29 10:46:22 -0700
commit3e19ae7c6fd62978ae518b17ae0e30ab8d17ed07 (patch)
treea2a0d43193565df027b20c7b63a36a1ffe8e3a99 /net/bridge/br_fdb.c
parent84fe73996c2e7407006002ef92d7354a56b69fed (diff)
net: bridge: use READ_ONCE() and WRITE_ONCE() compiler barriers for fdb->dst
Annotate the writer side of fdb->dst: - fdb_create() - br_fdb_update() - fdb_add_entry() - br_fdb_external_learn_add() with WRITE_ONCE() and the reader side: - br_fdb_test_addr() - br_fdb_update() - fdb_fill_info() - fdb_add_entry() - fdb_delete_by_addr_and_port() - br_fdb_external_learn_add() - br_switchdev_fdb_notify() with compiler barriers such that the readers do not attempt to reload fdb->dst multiple times, leading to potentially different destination ports when the fdb entry is updated concurrently. This is especially important in read-side sections where fdb->dst is used more than once, but let's convert all accesses for the sake of uniformity. Suggested-by: Nikolay Aleksandrov <nikolay@nvidia.com> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge/br_fdb.c')
-rw-r--r--net/bridge/br_fdb.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 16f9434fdb5d..dc3ecf2d5637 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -440,9 +440,14 @@ int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
if (!port)
ret = 0;
else {
+ const struct net_bridge_port *dst = NULL;
+
fdb = br_fdb_find_rcu(port->br, addr, 0);
- ret = fdb && fdb->dst && fdb->dst->dev != dev &&
- fdb->dst->state == BR_STATE_FORWARDING;
+ if (fdb)
+ dst = READ_ONCE(fdb->dst);
+
+ ret = dst && dst->dev != dev &&
+ dst->state == BR_STATE_FORWARDING;
}
rcu_read_unlock();
@@ -509,7 +514,7 @@ static struct net_bridge_fdb_entry *fdb_create(struct net_bridge *br,
fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
if (fdb) {
memcpy(fdb->key.addr.addr, addr, ETH_ALEN);
- fdb->dst = source;
+ WRITE_ONCE(fdb->dst, source);
fdb->key.vlan_id = vid;
fdb->flags = flags;
fdb->updated = fdb->used = jiffies;
@@ -600,10 +605,10 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
}
/* fastpath: update of existing entry */
- if (unlikely(source != fdb->dst &&
+ if (unlikely(source != READ_ONCE(fdb->dst) &&
!test_bit(BR_FDB_STICKY, &fdb->flags))) {
br_switchdev_fdb_notify(fdb, RTM_DELNEIGH);
- fdb->dst = source;
+ WRITE_ONCE(fdb->dst, source);
fdb_modified = true;
/* Take over HW learned entry */
if (unlikely(test_bit(BR_FDB_ADDED_BY_EXT_LEARN,
@@ -650,6 +655,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
const struct net_bridge_fdb_entry *fdb,
u32 portid, u32 seq, int type, unsigned int flags)
{
+ const struct net_bridge_port *dst = READ_ONCE(fdb->dst);
unsigned long now = jiffies;
struct nda_cacheinfo ci;
struct nlmsghdr *nlh;
@@ -665,7 +671,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
ndm->ndm_pad2 = 0;
ndm->ndm_flags = 0;
ndm->ndm_type = 0;
- ndm->ndm_ifindex = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
+ ndm->ndm_ifindex = dst ? dst->dev->ifindex : br->dev->ifindex;
ndm->ndm_state = fdb_to_nud(br, fdb);
if (test_bit(BR_FDB_OFFLOADED, &fdb->flags))
@@ -964,8 +970,8 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
if (flags & NLM_F_EXCL)
return -EEXIST;
- if (fdb->dst != source) {
- fdb->dst = source;
+ if (READ_ONCE(fdb->dst) != source) {
+ WRITE_ONCE(fdb->dst, source);
modified = true;
}
}
@@ -1132,7 +1138,7 @@ static int fdb_delete_by_addr_and_port(struct net_bridge *br,
struct net_bridge_fdb_entry *fdb;
fdb = br_fdb_find(br, addr, vlan);
- if (!fdb || fdb->dst != p)
+ if (!fdb || READ_ONCE(fdb->dst) != p)
return -ENOENT;
fdb_delete(br, fdb, true);
@@ -1281,8 +1287,8 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
} else {
fdb->updated = jiffies;
- if (fdb->dst != p) {
- fdb->dst = p;
+ if (READ_ONCE(fdb->dst) != p) {
+ WRITE_ONCE(fdb->dst, p);
modified = true;
}