netdev - [RFC PATCH net-next 05/20] net: bridge: switchdev: make br_fdb_replay offer sleepable context to consumers

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Message-Id: <20210818120150.892647-6-vladimir.oltean@nxp.com>
Date:   Wed, 18 Aug 2021 15:01:35 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Vadym Kochan <vkochan@...vell.com>,
        Taras Chornyi <tchornyi@...vell.com>,
        Jiri Pirko <jiri@...dia.com>, Ido Schimmel <idosch@...dia.com>,
        UNGLinuxDriver@...rochip.com,
        Grygorii Strashko <grygorii.strashko@...com>,
        Marek Behun <kabel@...ckhole.sk>,
        DENG Qingfang <dqfext@...il.com>,
        Kurt Kanzenbach <kurt@...utronix.de>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        George McCollister <george.mccollister@...il.com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        Julian Wiedmann <jwi@...ux.ibm.com>,
        Karsten Graul <kgraul@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Ivan Vecera <ivecera@...hat.com>,
        Vlad Buslov <vladbu@...dia.com>,
        Jianbo Liu <jianbol@...dia.com>,
        Mark Bloch <mbloch@...dia.com>, Roi Dayan <roid@...dia.com>,
        Tobias Waldekranz <tobias@...dekranz.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>
Subject: [RFC PATCH net-next 05/20] net: bridge: switchdev: make br_fdb_replay offer sleepable context to consumers

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@....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