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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 <krkumar2@in.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Krishna Kumar 2010-08-04 06:15:59 +00:00 committed by David S. Miller
parent bfb564e739
commit 1565c7c1c4
2 changed files with 90 additions and 18 deletions
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99
drivers/net/macvtap.c
View File

@ -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;
return rcu_dereference(vlan->tap);
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;
}
/* 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);
}
/*

9
include/linux/if_macvlan.h
View File

@ -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,