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xen-netfront: recreate queues correctly when reconnecting

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When reconnecting to the backend (after a resume/migration, for example),
a different number of queues may be required (since the guest may have
moved to a different host with different capabilities).  During the
reconnection the old queues are torn down and new ones created.

Introduce xennet_create_queues() and xennet_destroy_queues() that fixes
three bugs during the reconnection.

- The old info->queues was leaked.
- The old queue's napi instances were not deleted.
- The new queue's napi instances were left disabled (which meant no
  packets could be received).

The xennet_destroy_queues() calls is deferred until the reconnection
instead of the disconnection (in xennet_disconnect_backend()) because
napi_disable() might sleep.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Vrabel 2014-06-18 10:47:28 +01:00 committed by David S. Miller
parent 765418694b
commit ce58725fec
1 changed files with 72 additions and 32 deletions
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104
drivers/net/xen-netfront.c
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@ -1699,8 +1699,6 @@ static int xennet_init_queue(struct netfront_queue *queue)
goto exit_free_tx;
}
netif_napi_add(queue->info->netdev, &queue->napi, xennet_poll, 64);
return 0;
exit_free_tx:
@ -1791,6 +1789,70 @@ error:
return err;
}
static void xennet_destroy_queues(struct netfront_info *info)
{
unsigned int i;
rtnl_lock();
for (i = 0; i < info->netdev->real_num_tx_queues; i++) {
struct netfront_queue *queue = &info->queues[i];
if (netif_running(info->netdev))
napi_disable(&queue->napi);
netif_napi_del(&queue->napi);
}
rtnl_unlock();
kfree(info->queues);
info->queues = NULL;
}
static int xennet_create_queues(struct netfront_info *info,
unsigned int num_queues)
{
unsigned int i;
int ret;
info->queues = kcalloc(num_queues, sizeof(struct netfront_queue),
GFP_KERNEL);
if (!info->queues)
return -ENOMEM;
rtnl_lock();
for (i = 0; i < num_queues; i++) {
struct netfront_queue *queue = &info->queues[i];
queue->id = i;
queue->info = info;
ret = xennet_init_queue(queue);
if (ret < 0) {
dev_warn(&info->netdev->dev, "only created %d queues\n",
num_queues);
num_queues = i;
break;
}
netif_napi_add(queue->info->netdev, &queue->napi,
xennet_poll, 64);
if (netif_running(info->netdev))
napi_enable(&queue->napi);
}
netif_set_real_num_tx_queues(info->netdev, num_queues);
rtnl_unlock();
if (num_queues == 0) {
dev_err(&info->netdev->dev, "no queues\n");
return -EINVAL;
}
return 0;
}
/* Common code used when first setting up, and when resuming. */
static int talk_to_netback(struct xenbus_device *dev,
struct netfront_info *info)
@ -1827,42 +1889,20 @@ static int talk_to_netback(struct xenbus_device *dev,
goto out;
}
/* Allocate array of queues */
info->queues = kcalloc(num_queues, sizeof(struct netfront_queue), GFP_KERNEL);
if (!info->queues) {
err = -ENOMEM;
goto out;
}
rtnl_lock();
netif_set_real_num_tx_queues(info->netdev, num_queues);
rtnl_unlock();
if (info->queues)
xennet_destroy_queues(info);
err = xennet_create_queues(info, num_queues);
if (err < 0)
goto destroy_ring;
/* Create shared ring, alloc event channel -- for each queue */
for (i = 0; i < num_queues; ++i) {
queue = &info->queues[i];
queue->id = i;
queue->info = info;
err = xennet_init_queue(queue);
if (err) {
/* xennet_init_queue() cleans up after itself on failure,
* but we still have to clean up any previously initialised
* queues. If i > 0, set num_queues to i, then goto
* destroy_ring, which calls xennet_disconnect_backend()
* to tidy up.
*/
if (i > 0) {
rtnl_lock();
netif_set_real_num_tx_queues(info->netdev, i);
rtnl_unlock();
goto destroy_ring;
} else {
goto out;
}
}
err = setup_netfront(dev, queue, feature_split_evtchn);
if (err) {
/* As for xennet_init_queue(), setup_netfront() will tidy
* up the current queue on error, but we need to clean up
/* setup_netfront() will tidy up the current
* queue on error, but we need to clean up
* those already allocated.
*/
if (i > 0) {