xen-netback: don't stop dealloc kthread too early
Reference count the number of packets in host stack, so that we don't
stop the deallocation thread too early. If not, we can end up with
xenvif_free permanently waiting for deallocation thread to unmap grefs.
Reported-by: Thomas Leonard <[email protected]>
Signed-off-by: Wei Liu <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Zoltan Kiss <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 4734472..08f659965 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1525,10 +1525,12 @@
/* remove traces of mapped pages and frag_list */
skb_frag_list_init(skb);
uarg = skb_shinfo(skb)->destructor_arg;
+ /* increase inflight counter to offset decrement in callback */
+ atomic_inc(&queue->inflight_packets);
uarg->callback(uarg, true);
skb_shinfo(skb)->destructor_arg = NULL;
- skb_shinfo(nskb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+ xenvif_skb_zerocopy_prepare(queue, nskb);
kfree_skb(nskb);
return 0;
@@ -1589,7 +1591,7 @@
if (net_ratelimit())
netdev_err(queue->vif->dev,
"Not enough memory to consolidate frag_list!\n");
- skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+ xenvif_skb_zerocopy_prepare(queue, skb);
kfree_skb(skb);
continue;
}
@@ -1609,7 +1611,7 @@
"Can't setup checksum in net_tx_action\n");
/* We have to set this flag to trigger the callback */
if (skb_shinfo(skb)->destructor_arg)
- skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+ xenvif_skb_zerocopy_prepare(queue, skb);
kfree_skb(skb);
continue;
}
@@ -1641,7 +1643,7 @@
* skb. E.g. the __pskb_pull_tail earlier can do such thing.
*/
if (skb_shinfo(skb)->destructor_arg) {
- skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+ xenvif_skb_zerocopy_prepare(queue, skb);
queue->stats.tx_zerocopy_sent++;
}
@@ -1681,6 +1683,7 @@
queue->stats.tx_zerocopy_success++;
else
queue->stats.tx_zerocopy_fail++;
+ xenvif_skb_zerocopy_complete(queue);
}
static inline void xenvif_tx_dealloc_action(struct xenvif_queue *queue)
@@ -2058,15 +2061,24 @@
return 0;
}
+static bool xenvif_dealloc_kthread_should_stop(struct xenvif_queue *queue)
+{
+ /* Dealloc thread must remain running until all inflight
+ * packets complete.
+ */
+ return kthread_should_stop() &&
+ !atomic_read(&queue->inflight_packets);
+}
+
int xenvif_dealloc_kthread(void *data)
{
struct xenvif_queue *queue = data;
- while (!kthread_should_stop()) {
+ for (;;) {
wait_event_interruptible(queue->dealloc_wq,
tx_dealloc_work_todo(queue) ||
- kthread_should_stop());
- if (kthread_should_stop())
+ xenvif_dealloc_kthread_should_stop(queue));
+ if (xenvif_dealloc_kthread_should_stop(queue))
break;
xenvif_tx_dealloc_action(queue);
