[PATCH 3.16 292/370] xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend()

Ben Hutchings
2017-03-10T13:41:11Z

From: Boris Ostrovsky <boris.ostrovsky@oracle.com>

commit 74470954857c264168d2b5a113904cf0cfd27d18 upstream.

rx_refill_timer should be deleted as soon as we disconnect from the
backend since otherwise it is possible for the timer to go off before
we get to xennet_destroy_queues(). If this happens we may dereference
queue->rx.sring which is set to NULL in xennet_disconnect_backend().

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: del_timer_sync() was called from xennet_remove()
but that's also too late]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1440,6 +1440,8 @@ static void xennet_disconnect_backend(st
for (i = 0; i < num_queues; ++i) {
struct netfront_queue *queue = &info->queues[i];

+ del_timer_sync(&queue->rx_refill_timer);
+
if (queue->tx_irq && (queue->tx_irq == queue->rx_irq))
unbind_from_irqhandler(queue->tx_irq, queue);
if (queue->tx_irq && (queue->tx_irq != queue->rx_irq)) {
@@ -2360,8 +2362,6 @@ static int xennet_remove(struct xenbus_d
{
struct netfront_info *info = dev_get_drvdata(&dev->dev);
unsigned int num_queues = info->netdev->real_num_tx_queues;
- struct netfront_queue *queue = NULL;
- unsigned int i = 0;

dev_dbg(&dev->dev, "%s\n", dev->nodename);

@@ -2371,11 +2371,6 @@ static int xennet_remove(struct xenbus_d

unregister_netdev(info->netdev);

- for (i = 0; i < num_queues; ++i) {
- queue = &info->queues[i];
- del_timer_sync(&queue->rx_refill_timer);
- }
-
if (num_queues) {
kfree(info->queues);
info->queues = NULL;