[PATCH net-next] macvtap/macvlan: use IFF_NO_QUEUE

From: Jason Wang
Date: Mon Aug 24 2015 - 04:33:24 EST

For macvlan, switch to use IFF_NO_QUEUE instead of tx_queue_len = 0.

For macvtap, after commit 6acf54f1cf0a6747bac9fea26f34cfc5a9029523
("macvtap: Add support of packet capture on macvtap
device."). Multiqueue macvtap suffers from single qdisc lock
contention. This is because macvtap claims a non zero tx_queue_len and
it reuses this value as it socket receive queue size.Thanks to
IFF_NO_QUEUE, we can remove the lock contention without breaking
existing socket receive queue length logic.

Cc: Patrick McHardy <kaber@xxxxxxxxx>
Cc: Vladislav Yasevich <vyasevic@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
drivers/net/macvlan.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 47da435..09d8718 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1056,7 +1056,7 @@ void macvlan_common_setup(struct net_device *dev)

dev->priv_flags &= ~IFF_TX_SKB_SHARING;
- dev->priv_flags |= IFF_UNICAST_FLT;
+ dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
dev->netdev_ops = &macvlan_netdev_ops;
dev->destructor = free_netdev;
dev->header_ops = &macvlan_hard_header_ops;
@@ -1067,7 +1067,6 @@ EXPORT_SYMBOL_GPL(macvlan_common_setup);
static void macvlan_setup(struct net_device *dev)
- dev->tx_queue_len = 0;

static int macvlan_port_create(struct net_device *dev)

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