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Commit 67fa3660 authored by Paul Durrant's avatar Paul Durrant Committed by David S. Miller
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xen-netback: clear vif->task on disconnect 



xenvif_start_xmit() relies on checking vif->task for NULL to determine
whether the vif is ready to accept packets. The task thread is stopped in
xenvif_disconnect() but task is not set to NULL. Thus, on a re-connect the
check will give a false positive.

Also since commit ea732dff (Handle backend
state transitions in a more robust way) it should not be possible for
xenvif_connect() to be called if the vif is already connected so change the
check of vif->tx_irq to a BUG_ON() and also add a BUG_ON(vif->task).

Signed-off-by: default avatarPaul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: default avatarWei Liu <wei.liu2@citrix.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7ce5a27f

drivers/net/xen-netback/interface.c

+12 −8
Original line number Diff line number Diff line
@@ -368,11 +368,11 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, 
		   unsigned long rx_ring_ref, unsigned int tx_evtchn,

		   unsigned int rx_evtchn)

{

	struct task_struct *task;

	int err = -ENOMEM;



	/* Already connected through? */

	if (vif->tx_irq)

		return 0;

	BUG_ON(vif->tx_irq);

	BUG_ON(vif->task);



	err = xenvif_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);

	if (err < 0)
@@ -411,14 +411,16 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref, 
	}



	init_waitqueue_head(&vif->wq);

	vif->task = kthread_create(xenvif_kthread,

	task = kthread_create(xenvif_kthread,

			      (void *)vif, "%s", vif->dev->name);

	if (IS_ERR(vif->task)) {

	if (IS_ERR(task)) {

		pr_warn("Could not allocate kthread for %s\n", vif->dev->name);

		err = PTR_ERR(vif->task);

		err = PTR_ERR(task);

		goto err_rx_unbind;

	}



	vif->task = task;



	rtnl_lock();

	if (!vif->can_sg && vif->dev->mtu > ETH_DATA_LEN)

		dev_set_mtu(vif->dev, ETH_DATA_LEN);
@@ -461,8 +463,10 @@ void xenvif_disconnect(struct xenvif *vif) 
	if (netif_carrier_ok(vif->dev))

		xenvif_carrier_off(vif);



	if (vif->task)

	if (vif->task) {

		kthread_stop(vif->task);

		vif->task = NULL;

	}



	if (vif->tx_irq) {

		if (vif->tx_irq == vif->rx_irq)