xen-netback: stop the guest rx thread after a fatal error

After commit e9d8b2c (xen-netback: disable rogue vif in kthread context), a fatal (protocol) error would leave the guest Rx thread spinning, wasting CPU time. Commit ecf08d2 (xen-netback: reintroduce guest Rx stall detection) made this even worse by removing a cond_resched() from this path. Since a fatal error is non-recoverable, just allow the guest Rx thread to exit. This requires taking additional refs to the task so the thread exiting early is handled safely. Signed-off-by: David Vrabel <[email protected]> Reported-by: Julien Grall <[email protected]> Tested-by: Julien Grall <[email protected]> Acked-by: Wei Liu <[email protected]> Signed-off-by: David S. Miller <[email protected]>
raspberrypi · Feb 3, 2015 · 42b5212 · 42b5212
1 parent 5a2e87b
commit 42b5212
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Showing 2 changed files with 3 additions and 2 deletions.
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
@@ -578,6 +578,7 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref,
 		goto err_rx_unbind;
 	}
 	queue->task = task;
+	get_task_struct(task);
 
 	task = kthread_create(xenvif_dealloc_kthread,
 			      (void *)queue, "%s-dealloc", queue->name);
@@ -634,6 +635,7 @@ void xenvif_disconnect(struct xenvif *vif)
 
 		if (queue->task) {
 			kthread_stop(queue->task);
+			put_task_struct(queue->task);
 			queue->task = NULL;
 		}
 

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
@@ -2109,8 +2109,7 @@ int xenvif_kthread_guest_rx(void *data)
 		 */
 		if (unlikely(vif->disabled && queue->id == 0)) {
 			xenvif_carrier_off(vif);
-			xenvif_rx_queue_purge(queue);
-			continue;
+			break;
 		}
 
 		if (!skb_queue_empty(&queue->rx_queue))