From 1565c7c1c4c8e931bdba66abc8aa6f141a406872 Mon Sep 17 00:00:00 2001 From: Krishna Kumar Date: Wed, 4 Aug 2010 06:15:59 +0000 Subject: [PATCH] macvtap: Implement multiqueue for macvtap driver Implement multiqueue facility for macvtap driver. The idea is that a macvtap device can be opened multiple times and the fd's can be used to register eg, as backend for vhost. Signed-off-by: Krishna Kumar Signed-off-by: David S. Miller --- drivers/net/macvtap.c | 99 +++++++++++++++++++++++++++++++------- include/linux/if_macvlan.h | 9 +++- 2 files changed, 90 insertions(+), 18 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 3b1c54a9c6ef..42567279843e 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -84,26 +84,45 @@ static const struct proto_ops macvtap_socket_ops; static DEFINE_SPINLOCK(macvtap_lock); /* - * Choose the next free queue, for now there is only one + * get_slot: return a [unused/occupied] slot in vlan->taps[]: + * - if 'q' is NULL, return the first empty slot; + * - otherwise, return the slot this pointer occupies. */ +static int get_slot(struct macvlan_dev *vlan, struct macvtap_queue *q) +{ + int i; + + for (i = 0; i < MAX_MACVTAP_QUEUES; i++) { + if (rcu_dereference(vlan->taps[i]) == q) + return i; + } + + /* Should never happen */ + BUG_ON(1); +} + static int macvtap_set_queue(struct net_device *dev, struct file *file, struct macvtap_queue *q) { struct macvlan_dev *vlan = netdev_priv(dev); + int index; int err = -EBUSY; spin_lock(&macvtap_lock); - if (rcu_dereference(vlan->tap)) + if (vlan->numvtaps == MAX_MACVTAP_QUEUES) goto out; err = 0; + index = get_slot(vlan, NULL); rcu_assign_pointer(q->vlan, vlan); - rcu_assign_pointer(vlan->tap, q); + rcu_assign_pointer(vlan->taps[index], q); sock_hold(&q->sk); q->file = file; file->private_data = q; + vlan->numvtaps++; + out: spin_unlock(&macvtap_lock); return err; @@ -124,9 +143,12 @@ static void macvtap_put_queue(struct macvtap_queue *q) spin_lock(&macvtap_lock); vlan = rcu_dereference(q->vlan); if (vlan) { - rcu_assign_pointer(vlan->tap, NULL); + int index = get_slot(vlan, q); + + rcu_assign_pointer(vlan->taps[index], NULL); rcu_assign_pointer(q->vlan, NULL); sock_put(&q->sk); + --vlan->numvtaps; } spin_unlock(&macvtap_lock); @@ -136,39 +158,82 @@ static void macvtap_put_queue(struct macvtap_queue *q) } /* - * Since we only support one queue, just dereference the pointer. + * Select a queue based on the rxq of the device on which this packet + * arrived. If the incoming device is not mq, calculate a flow hash + * to select a queue. If all fails, find the first available queue. + * Cache vlan->numvtaps since it can become zero during the execution + * of this function. */ static struct macvtap_queue *macvtap_get_queue(struct net_device *dev, struct sk_buff *skb) { struct macvlan_dev *vlan = netdev_priv(dev); + struct macvtap_queue *tap = NULL; + int numvtaps = vlan->numvtaps; + __u32 rxq; + + if (!numvtaps) + goto out; + + if (likely(skb_rx_queue_recorded(skb))) { + rxq = skb_get_rx_queue(skb); + + while (unlikely(rxq >= numvtaps)) + rxq -= numvtaps; + + tap = rcu_dereference(vlan->taps[rxq]); + if (tap) + goto out; + } + + /* Check if we can use flow to select a queue */ + rxq = skb_get_rxhash(skb); + if (rxq) { + tap = rcu_dereference(vlan->taps[rxq % numvtaps]); + if (tap) + goto out; + } - return rcu_dereference(vlan->tap); + /* Everything failed - find first available queue */ + for (rxq = 0; rxq < MAX_MACVTAP_QUEUES; rxq++) { + tap = rcu_dereference(vlan->taps[rxq]); + if (tap) + break; + } + +out: + return tap; } /* * The net_device is going away, give up the reference - * that it holds on the queue (all the queues one day) - * and safely set the pointer from the queues to NULL. + * that it holds on all queues and safely set the pointer + * from the queues to NULL. */ static void macvtap_del_queues(struct net_device *dev) { struct macvlan_dev *vlan = netdev_priv(dev); - struct macvtap_queue *q; + struct macvtap_queue *q, *qlist[MAX_MACVTAP_QUEUES]; + int i, j = 0; + /* macvtap_put_queue can free some slots, so go through all slots */ spin_lock(&macvtap_lock); - q = rcu_dereference(vlan->tap); - if (!q) { - spin_unlock(&macvtap_lock); - return; + for (i = 0; i < MAX_MACVTAP_QUEUES && vlan->numvtaps; i++) { + q = rcu_dereference(vlan->taps[i]); + if (q) { + qlist[j++] = q; + rcu_assign_pointer(vlan->taps[i], NULL); + rcu_assign_pointer(q->vlan, NULL); + vlan->numvtaps--; + } } - - rcu_assign_pointer(vlan->tap, NULL); - rcu_assign_pointer(q->vlan, NULL); + BUG_ON(vlan->numvtaps != 0); spin_unlock(&macvtap_lock); synchronize_rcu(); - sock_put(&q->sk); + + for (--j; j >= 0; j--) + sock_put(&qlist[j]->sk); } /* diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h index 35280b302290..8a2fd66a8b5f 100644 --- a/include/linux/if_macvlan.h +++ b/include/linux/if_macvlan.h @@ -40,6 +40,12 @@ struct macvlan_rx_stats { unsigned long rx_errors; }; +/* + * Maximum times a macvtap device can be opened. This can be used to + * configure the number of receive queue, e.g. for multiqueue virtio. + */ +#define MAX_MACVTAP_QUEUES (NR_CPUS < 16 ? NR_CPUS : 16) + struct macvlan_dev { struct net_device *dev; struct list_head list; @@ -50,7 +56,8 @@ struct macvlan_dev { enum macvlan_mode mode; int (*receive)(struct sk_buff *skb); int (*forward)(struct net_device *dev, struct sk_buff *skb); - struct macvtap_queue *tap; + struct macvtap_queue *taps[MAX_MACVTAP_QUEUES]; + int numvtaps; }; static inline void macvlan_count_rx(const struct macvlan_dev *vlan, -- 2.20.1