[kvm-devel] [PATCH] Fixup virtio_net TX timer

[Anthony Liguori]

Instead of introducing a new flag, I think we decided that we would make the
NO_NOTIFY flag be a hint and have both ends always notify when the ring is
full or empty.  This patch updates the QEMU virtio code to reflect this.

Signed-off-by: Anthony Liguori <[EMAIL PROTECTED]>

diff --git a/qemu/hw/virtio-net.c b/qemu/hw/virtio-net.c
index 9cd0789..296edf6 100644
--- a/qemu/hw/virtio-net.c
+++ b/qemu/hw/virtio-net.c
@@ -29,8 +29,6 @@
 #define VIRTIO_NET_F_TSO6      4
 #define VIRTIO_NET_F_MAC       5
 
-#define USE_TX_TIMER
-
 #define TX_TIMER_INTERVAL (1000 / 500)
 
 /* The config defining mac address (6 bytes) */
@@ -261,14 +259,15 @@ static void virtio_net_handle_tx(VirtIODevice *vdev, 
VirtQueue *vq)
 
     if (n->tx_timer_active &&
        (vq->vring.avail->idx - vq->last_avail_idx) == 64) {
-       vq->vring.used->flags &= ~VRING_USED_F_NOTIFY_ON_FULL;
+       vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
        qemu_del_timer(n->tx_timer);
        n->tx_timer_active = 0;
        virtio_net_flush_tx(n, vq);
     } else {
-       qemu_mod_timer(n->tx_timer, qemu_get_clock(vm_clock) + 
TX_TIMER_INTERVAL);
+       qemu_mod_timer(n->tx_timer,
+                      qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
        n->tx_timer_active = 1;
-       vq->vring.used->flags |= VRING_USED_F_NOTIFY_ON_FULL;
+       vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
     }
 }
 
@@ -276,7 +275,7 @@ static void virtio_net_tx_timer(void *opaque)
 {
     VirtIONet *n = opaque;
 
-    n->tx_vq->vring.used->flags &= ~VRING_USED_F_NOTIFY_ON_FULL;
+    n->tx_vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
     n->tx_timer_active = 0;
     virtio_net_flush_tx(n, n->tx_vq);
 }
diff --git a/qemu/hw/virtio.c b/qemu/hw/virtio.c
index e7fcfa3..b78c2c5 100644
--- a/qemu/hw/virtio.c
+++ b/qemu/hw/virtio.c
@@ -380,7 +380,9 @@ VirtQueue *virtio_add_queue(VirtIODevice *vdev, int 
queue_size,
 
 void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
 {
-    if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+    /* Always notify when queue is empty */
+    if (vq->vring.avail->idx != vq->last_avail_idx &&
+       (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
        return;
 
     vdev->isr = 1;
diff --git a/qemu/hw/virtio.h b/qemu/hw/virtio.h
index 21b96a3..dee97ba 100644
--- a/qemu/hw/virtio.h
+++ b/qemu/hw/virtio.h
@@ -39,7 +39,6 @@
 
 /* This means don't notify other side when buffer added. */
 #define VRING_USED_F_NO_NOTIFY 1
-#define VRING_USED_F_NOTIFY_ON_FULL  2
 /* This means don't interrupt guest when buffer consumed. */
 #define VRING_AVAIL_F_NO_INTERRUPT     1
 

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