netdev - [PATCH v3 3/5] ipvlan: unhash addresses without synchronize

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Message-ID: <20150714133553.22448.53507.stgit@buzz>
Date:	Tue, 14 Jul 2015 16:35:53 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	linux-netdev <netdev@...r.kernel.org>,
	Mahesh Bandewar <maheshb@...gle.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Jiri Benc <jbenc@...hat.com>
Subject: [PATCH v3 3/5] ipvlan: unhash addresses without synchronize_rcu

All structures used in traffic forwarding are rcu-protected:
ipvl_addr, ipvl_dev and ipvl_port. Thus we can unhash addresses
without synchronization. We'll anyway hash it back into the same
bucket: in worst case lockless lookup will scan hash once again.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
---
 drivers/net/ipvlan/ipvlan.h      |    2 +-
 drivers/net/ipvlan/ipvlan_core.c |    4 +---
 drivers/net/ipvlan/ipvlan_main.c |    8 ++++----
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ipvlan/ipvlan.h b/drivers/net/ipvlan/ipvlan.h
index 68e2549c28c6..40f9d7e4a0ea 100644
--- a/drivers/net/ipvlan/ipvlan.h
+++ b/drivers/net/ipvlan/ipvlan.h
@@ -122,5 +122,5 @@ struct ipvl_addr *ipvlan_find_addr(const struct ipvl_dev *ipvlan,
 bool ipvlan_addr_busy(struct ipvl_port *port, void *iaddr, bool is_v6);
 struct ipvl_addr *ipvlan_ht_addr_lookup(const struct ipvl_port *port,
 					const void *iaddr, bool is_v6);
-void ipvlan_ht_addr_del(struct ipvl_addr *addr, bool sync);
+void ipvlan_ht_addr_del(struct ipvl_addr *addr);
 #endif /* __IPVLAN_H */
diff --git a/drivers/net/ipvlan/ipvlan_core.c b/drivers/net/ipvlan/ipvlan_core.c
index 8afbedad620d..8f8628a0adba 100644
--- a/drivers/net/ipvlan/ipvlan_core.c
+++ b/drivers/net/ipvlan/ipvlan_core.c
@@ -85,11 +85,9 @@ void ipvlan_ht_addr_add(struct ipvl_dev *ipvlan, struct ipvl_addr *addr)
 		hlist_add_head_rcu(&addr->hlnode, &port->hlhead[hash]);
 }
 
-void ipvlan_ht_addr_del(struct ipvl_addr *addr, bool sync)
+void ipvlan_ht_addr_del(struct ipvl_addr *addr)
 {
 	hlist_del_init_rcu(&addr->hlnode);
-	if (sync)
-		synchronize_rcu();
 }
 
 struct ipvl_addr *ipvlan_find_addr(const struct ipvl_dev *ipvlan,
diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c
index 7d81e37c3f76..e995bc501ee6 100644
--- a/drivers/net/ipvlan/ipvlan_main.c
+++ b/drivers/net/ipvlan/ipvlan_main.c
@@ -171,7 +171,7 @@ static int ipvlan_stop(struct net_device *dev)
 	dev_uc_del(phy_dev, phy_dev->dev_addr);
 
 	list_for_each_entry(addr, &ipvlan->addrs, anode)
-		ipvlan_ht_addr_del(addr, !dev->dismantle);
+		ipvlan_ht_addr_del(addr);
 
 	return 0;
 }
@@ -505,7 +505,7 @@ static void ipvlan_link_delete(struct net_device *dev, struct list_head *head)
 	struct ipvl_addr *addr, *next;
 
 	list_for_each_entry_safe(addr, next, &ipvlan->addrs, anode) {
-		ipvlan_ht_addr_del(addr, !dev->dismantle);
+		ipvlan_ht_addr_del(addr);
 		list_del(&addr->anode);
 		kfree_rcu(addr, rcu);
 	}
@@ -641,7 +641,7 @@ static void ipvlan_del_addr6(struct ipvl_dev *ipvlan, struct in6_addr *ip6_addr)
 	if (!addr)
 		return;
 
-	ipvlan_ht_addr_del(addr, true);
+	ipvlan_ht_addr_del(addr);
 	list_del(&addr->anode);
 	kfree_rcu(addr, rcu);
 
@@ -711,7 +711,7 @@ static void ipvlan_del_addr4(struct ipvl_dev *ipvlan, struct in_addr *ip4_addr)
 	if (!addr)
 		return;
 
-	ipvlan_ht_addr_del(addr, true);
+	ipvlan_ht_addr_del(addr);
 	list_del(&addr->anode);
 	kfree_rcu(addr, rcu);
 

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