xen-netback: fix race between napi_complete() and interrupt handler

[cascardo/linux.git] / drivers / net / xen-netback / interface.c

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index ef05c5c..20e9def 100644 (file)
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -75,32 +75,8 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
        work_done = xenvif_tx_action(vif, budget);
 
        if (work_done < budget) {
-               int more_to_do = 0;
-               unsigned long flags;
-
-               /* It is necessary to disable IRQ before calling
-                * RING_HAS_UNCONSUMED_REQUESTS. Otherwise we might
-                * lose event from the frontend.
-                *
-                * Consider:
-                *   RING_HAS_UNCONSUMED_REQUESTS
-                *   <frontend generates event to trigger napi_schedule>
-                *   __napi_complete
-                *
-                * This handler is still in scheduled state so the
-                * event has no effect at all. After __napi_complete
-                * this handler is descheduled and cannot get
-                * scheduled again. We lose event in this case and the ring
-                * will be completely stalled.
-                */
-
-               local_irq_save(flags);
-
-               RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
-               if (!more_to_do)
-                       __napi_complete(napi);
-
-               local_irq_restore(flags);
+               napi_complete(napi);
+               xenvif_napi_schedule_or_enable_events(vif);
        }
 
        return work_done;
@@ -194,7 +170,7 @@ static void xenvif_up(struct xenvif *vif)
        enable_irq(vif->tx_irq);
        if (vif->tx_irq != vif->rx_irq)
                enable_irq(vif->rx_irq);
-       xenvif_check_rx_xenvif(vif);
+       xenvif_napi_schedule_or_enable_events(vif);
 }
 
 static void xenvif_down(struct xenvif *vif)