This patch adds TUNSETQUEUE ioctl to let userspace can temporarily disable or
enable a queue of macvtap. This is used to be compatible at API layer of tuntap
to simplify the userspace to manage the queues.
This is done by just introduce a pointer detached which was set when the queue
were detached. Only the queue with NULL set to this pointer can be used to
forward packets.
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
drivers/net/macvtap.c | 147 +++++++++++++++++++++++++++++++++++--------
include/linux/if_macvlan.h | 7 ++
2 files changed, 126 insertions(+), 28 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index e3f9344..06b10a5 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -85,67 +85,131 @@ static const struct proto_ops macvtap_socket_ops;
*/
static DEFINE_SPINLOCK(macvtap_lock);
+static void macvtap_swap_slot(struct macvlan_dev *vlan, int a, int b)
+{
+ struct macvtap_queue *q1, *q2;
+
+ if (a == b)
+ return;
+
+ q1 = rcu_dereference_protected(vlan->taps[a],
+ lockdep_is_held(&macvtap_lock));
+ q2 = rcu_dereference_protected(vlan->taps[b],
+ lockdep_is_held(&macvtap_lock));
+
+ BUG_ON(q1 == NULL || q2 == NULL);
+
+ rcu_assign_pointer(vlan->taps[a], vlan->taps[b]);
+ rcu_assign_pointer(vlan->taps[b], q1);
+
+ q1->queue_index = b;
+ q2->queue_index = a;
+}
+
static int macvtap_set_queue(struct net_device *dev, struct file *file,
- struct macvtap_queue *q)
+ struct macvtap_queue *q, bool enable)
{
struct macvlan_dev *vlan = netdev_priv(dev);
int err = -EBUSY;
+ int total;
spin_lock(&macvtap_lock);
- if (vlan->numvtaps == MAX_MACVTAP_QUEUES)
+
+ total = vlan->numvtaps + vlan->numdisabled;
+ if (!enable && total == MAX_MACVTAP_QUEUES)
+ goto out;
+
+ err = -EINVAL;
+ if (enable && q->queue_index < vlan->numvtaps)
goto out;
err = 0;
- rcu_assign_pointer(q->vlan, vlan);
- rcu_assign_pointer(vlan->taps[vlan->numvtaps], q);
- sock_hold(&q->sk);
- q->file = file;
- q->queue_index = vlan->numvtaps;
- file->private_data = q;
+ if (enable) {
+ BUG_ON(q->queue_index >= total);
+ macvtap_swap_slot(vlan, q->queue_index, vlan->numvtaps);
+ --vlan->numdisabled;
+ } else {
+ rcu_assign_pointer(q->vlan, vlan);
+ rcu_assign_pointer(vlan->taps[total], q);
+ sock_hold(&q->sk);
+
+ q->file = file;
+ q->queue_index = total;
+ file->private_data = q;
+ if (vlan->numdisabled)
+ macvtap_swap_slot(vlan, vlan->numvtaps, total);
+
+ /* Make sure the pointers were seen before numvtaps. */
+ smp_wmb();
+ }
vlan->numvtaps++;
-
out:
spin_unlock(&macvtap_lock);
return err;
}
/*
- * The file owning the queue got closed, give up both
- * the reference that the files holds as well as the
- * one from the macvlan_dev if that still exists.
+ * The file owning the queue got closed or disabled.
+ *
+ * If closed give up both the reference that the files holds as well as the
+ * one from the macvlan_dev if that still exists. If disabled, reshuffle the
+ * array of taps.
*
* Using the spinlock makes sure that we don't get
* to the queue again after destroying it.
*/
-static void macvtap_put_queue(struct macvtap_queue *q)
+static int macvtap_put_queue(struct macvtap_queue *q, bool clean)
{
- struct macvtap_queue *nq;
struct macvlan_dev *vlan;
+ int err = -EINVAL;
spin_lock(&macvtap_lock);
vlan = rcu_dereference_protected(q->vlan,
lockdep_is_held(&macvtap_lock));
+
if (vlan) {
+ int total = vlan->numvtaps + vlan->numdisabled;
int index = q->queue_index;
- BUG_ON(index >= vlan->numvtaps);
+ bool disabled = q->queue_index >= vlan->numvtaps;
- rcu_assign_pointer(vlan->taps[index],
- vlan->taps[vlan->numvtaps - 1]);
- RCU_INIT_POINTER(q->vlan, NULL);
- nq = rcu_dereference_protected(vlan->taps[index],
- lockdep_is_held(&macvtap_lock));
- nq->queue_index = index;
+ if (!clean) {
+ BUG_ON(q->queue_index >= total);
+ if (q->queue_index >= vlan->numvtaps)
+ goto out;
+ }
- sock_put(&q->sk);
- --vlan->numvtaps;
- }
+ err = 0;
+ macvtap_swap_slot(vlan, index, total - 1);
+ if (!disabled && vlan->numdisabled)
+ macvtap_swap_slot(vlan, index, vlan->numvtaps - 1);
+
+ if (clean) {
+ RCU_INIT_POINTER(vlan->taps[total - 1], NULL);
+ RCU_INIT_POINTER(q->vlan, NULL);
+ sock_put(&q->sk);
+ if (disabled)
+ --vlan->numdisabled;
+ else
+ --vlan->numvtaps;
+ } else {
+ --vlan->numvtaps;
+ ++vlan->numdisabled;
+ }
+
+ } else if (clean)
+ err = 0;
+out:
spin_unlock(&macvtap_lock);
synchronize_rcu();
- sock_put(&q->sk);
+
+ if (clean)
+ sock_put(&q->sk);
+
+ return err;
}
/*
@@ -201,7 +265,7 @@ static void macvtap_del_queues(struct net_device *dev)
/* macvtap_put_queue can free some slots, so go through all slots */
spin_lock(&macvtap_lock);
- for (i = 0; i < vlan->numvtaps; i++) {
+ for (i = 0; i < vlan->numvtaps + vlan->numdisabled; i++) {
q = rcu_dereference_protected(vlan->taps[i],
lockdep_is_held(&macvtap_lock));
BUG_ON(q == NULL);
@@ -211,6 +275,7 @@ static void macvtap_del_queues(struct net_device *dev)
}
/* guarantee that any future macvtap_set_queue will fail */
vlan->numvtaps = MAX_MACVTAP_QUEUES;
+ vlan->numdisabled = 0;
spin_unlock(&macvtap_lock);
synchronize_rcu();
@@ -384,7 +449,7 @@ static int macvtap_open(struct inode *inode, struct file
*file)
if ((dev->features & NETIF_F_HIGHDMA) && (dev->features & NETIF_F_SG))
sock_set_flag(&q->sk, SOCK_ZEROCOPY);
- err = macvtap_set_queue(dev, file, q);
+ err = macvtap_set_queue(dev, file, q, false);
if (err)
sock_put(&q->sk);
@@ -398,7 +463,7 @@ out:
static int macvtap_release(struct inode *inode, struct file *file)
{
struct macvtap_queue *q = file->private_data;
- macvtap_put_queue(q);
+ macvtap_put_queue(q, true);
return 0;
}
@@ -922,6 +987,27 @@ static int macvtap_set_iff(struct file *file, struct ifreq
__user *ifr_u)
return 0;
}
+static int macvtap_ioctl_set_queue(struct file *file, unsigned int flags)
+{
+ struct macvtap_queue *q = file->private_data;
+ struct macvlan_dev *vlan;
+ int ret = -EINVAL;
+
+ vlan = macvtap_get_vlan(q);
+ if (!vlan)
+ goto done;
+
+ if (flags & IFF_ATTACH_QUEUE)
+ ret = macvtap_set_queue(vlan->dev, file, q, true);
+ else if (flags & IFF_DETACH_QUEUE)
+ ret = macvtap_put_queue(q, false);
+
+ macvtap_put_vlan(vlan);
+
+done:
+ return ret;
+}
+
/*
* provide compatibility with generic tun/tap interface
*/
@@ -954,6 +1040,11 @@ static long macvtap_ioctl(struct file *file, unsigned int
cmd,
macvtap_put_vlan(vlan);
return ret;
+ case TUNSETQUEUE:
+ if (get_user(u, &ifr->ifr_flags))
+ return -EFAULT;
+ return macvtap_ioctl_set_queue(file, u);
+
case TUNGETFEATURES:
if (put_user(IFF_TAP | IFF_NO_PI | IFF_VNET_HDR, up))
return -EFAULT;
diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index 32e943a..f134afb 100644
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -69,8 +69,15 @@ struct macvlan_dev {
u16 flags;
int (*receive)(struct sk_buff *skb);
int (*forward)(struct net_device *dev, struct sk_buff *skb);
+ /* This array tracks all taps (include disabled ones) and will be
+ * reshuffled to keep the following order:
+ * [0, numvtaps) : enabled taps,
+ * [numvtaps, numvtaps + numdisabled) : disabled taps,
+ * [numvtaps + numdisabled, MAX_MACVTAP_QUEUES) : unused slots
+ */
struct macvtap_queue *taps[MAX_MACVTAP_QUEUES];
int numvtaps;
+ int numdisabled;
int minor;
};
--
1.7.1
--
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