macvtap: eliminate linear search

[deliverable/linux.git] / drivers / net / macvtap.c

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 59e9605de316809a702951a5c6de3dbee3a43a69..5ccba99b15f4c1ea53e3cb6522e0598a00a845e5 100644 (file)
--- 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);
 
-               RCU_INIT_POINTER(vlan->taps[index], NULL);
+               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[vlan->numvtaps - 1], NULL);
                RCU_INIT_POINTER(q->vlan, NULL);
                sock_put(&q->sk);
                --vlan->numvtaps;
@@ -172,7 +160,7 @@ static struct macvtap_queue *macvtap_get_queue(struct net_device *dev,
 {
        struct macvlan_dev *vlan = netdev_priv(dev);
        struct macvtap_queue *tap = NULL;
-       int numvtaps = vlan->numvtaps;
+       int numvtaps = ACCESS_ONCE(vlan->numvtaps);
        __u32 rxq;
 
        if (!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);
@@ -845,7 +821,9 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
        ssize_t ret = 0;
 
        while (len) {
-               prepare_to_wait(sk_sleep(&q->sk), &wait, TASK_INTERRUPTIBLE);
+               if (!noblock)
+                       prepare_to_wait(sk_sleep(&q->sk), &wait,
+                                       TASK_INTERRUPTIBLE);
 
                /* Read frames from the queue */
                skb = skb_dequeue(&q->sk.sk_receive_queue);
@@ -867,7 +845,8 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
                break;
        }
 
-       finish_wait(sk_sleep(&q->sk), &wait);
+       if (!noblock)
+               finish_wait(sk_sleep(&q->sk), &wait);
        return ret;
 }
 
@@ -890,6 +869,24 @@ out:
        return ret;
 }
 
+static struct macvlan_dev *macvtap_get_vlan(struct macvtap_queue *q)
+{
+       struct macvlan_dev *vlan;
+
+       rcu_read_lock_bh();
+       vlan = rcu_dereference_bh(q->vlan);
+       if (vlan)
+               dev_hold(vlan->dev);
+       rcu_read_unlock_bh();
+
+       return vlan;
+}
+
+static void macvtap_put_vlan(struct macvlan_dev *vlan)
+{
+       dev_put(vlan->dev);
+}
+
 /*
  * provide compatibility with generic tun/tap interface
  */
@@ -921,12 +918,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
                return ret;
 
        case TUNGETIFF:
-               rcu_read_lock_bh();
-               vlan = rcu_dereference_bh(q->vlan);
-               if (vlan)
-                       dev_hold(vlan->dev);
-               rcu_read_unlock_bh();
-
+               vlan = macvtap_get_vlan(q);
                if (!vlan)
                        return -ENOLINK;
 
@@ -934,7 +926,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
                if (copy_to_user(&ifr->ifr_name, vlan->dev->name, IFNAMSIZ) ||
                    put_user(q->flags, &ifr->ifr_flags))
                        ret = -EFAULT;
-               dev_put(vlan->dev);
+               macvtap_put_vlan(vlan);
                return ret;
 
        case TUNGETFEATURES:
@@ -1053,7 +1045,7 @@ EXPORT_SYMBOL_GPL(macvtap_get_socket);
 static int macvtap_device_event(struct notifier_block *unused,
                                unsigned long event, void *ptr)
 {
-       struct net_device *dev = ptr;
+       struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct macvlan_dev *vlan;
        struct device *classdev;
        dev_t devt;