[PATCH v2 net-next 2/5] net: bridge: switchdev: make br_fdb_replay offer sleepable context to consumers

Vladimir Oltean
2021-08-19T16:08:12Z

Now that the SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE events are notified on
the blocking chain, it would be nice if we could also drop the
rcu_read_lock() atomic context from br_fdb_replay() so that drivers can
actually benefit from the blocking context and simplify their logic.

Do something similar to what is done in br_mdb_queue_one/br_mdb_replay_one,
except the fact that FDB entries are held in a hash list.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
net/bridge/br_fdb.c | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 0bdbcfc53914..36f4e3b8d21b 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -752,12 +752,28 @@ static int br_fdb_replay_one(struct net_bridge *br, struct notifier_block *nb,
return notifier_to_errno(err);
}

+static int br_fdb_queue_one(struct hlist_head *fdb_list,
+ const struct net_bridge_fdb_entry *fdb)
+{
+ struct net_bridge_fdb_entry *fdb_new;
+
+ fdb_new = kmemdup(fdb, sizeof(*fdb), GFP_ATOMIC);
+ if (!fdb_new)
+ return -ENOMEM;
+
+ hlist_add_head_rcu(&fdb_new->fdb_node, fdb_list);
+
+ return 0;
+}
+
int br_fdb_replay(const struct net_device *br_dev, const void *ctx, bool adding,
struct notifier_block *nb)
{
struct net_bridge_fdb_entry *fdb;
+ struct hlist_node *tmp;
struct net_bridge *br;
unsigned long action;
+ HLIST_HEAD(fdb_list);
int err = 0;

if (!nb)
@@ -770,20 +786,34 @@ int br_fdb_replay(const struct net_device *br_dev, const void *ctx, bool adding,

br = netdev_priv(br_dev);

+ rcu_read_lock();
+
+ hlist_for_each_entry_rcu(fdb, &br->fdb_list, fdb_node) {
+ err = br_fdb_queue_one(&fdb_list, fdb);
+ if (err) {
+ rcu_read_unlock();
+ goto out_free_fdb;
+ }
+ }
+
+ rcu_read_unlock();
+
if (adding)
action = SWITCHDEV_FDB_ADD_TO_DEVICE;
else
action = SWITCHDEV_FDB_DEL_TO_DEVICE;

- rcu_read_lock();
-
- hlist_for_each_entry_rcu(fdb, &br->fdb_list, fdb_node) {
+ hlist_for_each_entry(fdb, &fdb_list, fdb_node) {
err = br_fdb_replay_one(br, nb, fdb, action, ctx);
if (err)
break;
}

- rcu_read_unlock();
+out_free_fdb:
+ hlist_for_each_entry_safe(fdb, tmp, &fdb_list, fdb_node) {
+ hlist_del_rcu(&fdb->fdb_node);
+ kfree(fdb);
+ }

return err;
}
--
2.25.1