From 376b1aabe1f53aad80615d05ddb8c43670be6a5c Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Wed, 5 Jun 2013 23:54:38 +0000 Subject: [PATCH] macvtap: eliminate linear search Linear search were used in both get_slot() and macvtap_get_queue(), this is because: - macvtap didn't reshuffle the array of taps when create or destroy a queue, so when adding a new queue, macvtap must do linear search to find a location for the new queue. This will also complicate the TUNSETQUEUE implementation for multiqueue API. - the queue itself didn't track the queue index, so the we must do a linear search in the array to find the location of a existed queue. The solution is straightforward: reshuffle the array and introduce a queue_index to macvtap_queue. Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- drivers/net/macvtap.c | 64 ++++++++++++++++----------------------------------- 1 file changed, 20 insertions(+), 44 deletions(-) diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index d18130b..5ccba99b 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -44,6 +44,7 @@ struct macvtap_queue { struct macvlan_dev __rcu *vlan; struct file *file; unsigned int flags; + u16 queue_index; }; static struct proto macvtap_proto = { @@ -84,30 +85,10 @@ static const struct proto_ops macvtap_socket_ops; */ static DEFINE_SPINLOCK(macvtap_lock); -/* - * 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_protected(vlan->taps[i], - lockdep_is_held(&macvtap_lock)) == 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); @@ -115,12 +96,12 @@ static int macvtap_set_queue(struct net_device *dev, struct file *file, goto out; err = 0; - index = get_slot(vlan, NULL); rcu_assign_pointer(q->vlan, vlan); - rcu_assign_pointer(vlan->taps[index], q); + rcu_assign_pointer(vlan->taps[vlan->numvtaps], q); sock_hold(&q->sk); q->file = file; + q->queue_index = vlan->numvtaps; file->private_data = q; vlan->numvtaps++; @@ -140,15 +121,22 @@ out: */ static void macvtap_put_queue(struct macvtap_queue *q) { + struct macvtap_queue *nq; struct macvlan_dev *vlan; spin_lock(&macvtap_lock); vlan = rcu_dereference_protected(q->vlan, lockdep_is_held(&macvtap_lock)); if (vlan) { - int index = get_slot(vlan, q); + int index = q->queue_index; + BUG_ON(index >= vlan->numvtaps); + + nq = rcu_dereference_protected(vlan->taps[vlan->numvtaps - 1], + lockdep_is_held(&macvtap_lock)); + rcu_assign_pointer(vlan->taps[index], nq); + nq->queue_index = index; - RCU_INIT_POINTER(vlan->taps[index], NULL); + RCU_INIT_POINTER(vlan->taps[vlan->numvtaps - 1], NULL); RCU_INIT_POINTER(q->vlan, NULL); sock_put(&q->sk); --vlan->numvtaps; @@ -182,8 +170,7 @@ static struct macvtap_queue *macvtap_get_queue(struct net_device *dev, rxq = skb_get_rxhash(skb); if (rxq) { tap = rcu_dereference(vlan->taps[rxq % numvtaps]); - if (tap) - goto out; + goto out; } if (likely(skb_rx_queue_recorded(skb))) { @@ -193,17 +180,10 @@ static struct macvtap_queue *macvtap_get_queue(struct net_device *dev, rxq -= numvtaps; tap = rcu_dereference(vlan->taps[rxq]); - if (tap) - goto out; - } - - /* Everything failed - find first available queue */ - for (rxq = 0; rxq < MAX_MACVTAP_QUEUES; rxq++) { - tap = rcu_dereference(vlan->taps[rxq]); - if (tap) - break; + goto out; } + tap = rcu_dereference(vlan->taps[0]); out: return tap; } @@ -219,19 +199,15 @@ static void macvtap_del_queues(struct net_device *dev) 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); - for (i = 0; i < MAX_MACVTAP_QUEUES && vlan->numvtaps; i++) { + for (i = 0; i < vlan->numvtaps; i++) { q = rcu_dereference_protected(vlan->taps[i], lockdep_is_held(&macvtap_lock)); - if (q) { - qlist[j++] = q; - RCU_INIT_POINTER(vlan->taps[i], NULL); - RCU_INIT_POINTER(q->vlan, NULL); - vlan->numvtaps--; - } + BUG_ON(q == NULL); + qlist[j++] = q; + RCU_INIT_POINTER(vlan->taps[i], NULL); + RCU_INIT_POINTER(q->vlan, NULL); } - BUG_ON(vlan->numvtaps != 0); /* guarantee that any future macvtap_set_queue will fail */ vlan->numvtaps = MAX_MACVTAP_QUEUES; spin_unlock(&macvtap_lock); -- 2.7.4