net: notify iothread after flushing queue

virtio-net has code to flush the queue and notify the iothread
whenever new receive buffers are added by the guest.  That is
fine, and indeed we need to do the same in all other drivers.
However, notifying the iothread should be work for the network
subsystem.  And since we are at it we can add a little smartness:
if some of the queued packets already could not be delivered,
there is no need to notify the iothread.

Reported-by: Luigi Rizzo <rizzo@iet.unipi.it>
Cc: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Jan Kiszka <jan.kiszka@siemens.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
(cherry picked from commit 987a9b4800003567b1a47a379255e886a77d57ea)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index b1998b27d363fa9c84ceec215b7bd235b3a8525d..6490743290ed58596c997afa343927cacf81f5a8 100644 (file)
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -447,10 +447,6 @@ static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq)
     VirtIONet *n = to_virtio_net(vdev);
 
     qemu_flush_queued_packets(&n->nic->nc);
-
-    /* We now have RX buffers, signal to the IO thread to break out of the
-     * select to re-poll the tap file descriptor */
-    qemu_notify_event();
 }
 
 static int virtio_net_can_receive(NetClientState *nc)

diff --git a/net.c b/net.c
index 60043ddec694ef914cd340d250163954d25976e4..76a833675f35640c69fb327125a7d30c71245cb3 100644 (file)
--- a/net.c
+++ b/net.c
@@ -357,7 +357,12 @@ void qemu_flush_queued_packets(NetClientState *nc)
 {
     nc->receive_disabled = 0;
 
-    qemu_net_queue_flush(nc->send_queue);
+    if (qemu_net_queue_flush(nc->send_queue)) {
+        /* We emptied the queue successfully, signal to the IO thread to repoll
+         * the file descriptor (for tap, for example).
+         */
+        qemu_notify_event();
+    }
 }
 
 static ssize_t qemu_send_packet_async_with_flags(NetClientState *sender,

diff --git a/net/queue.c b/net/queue.c
index e8030aafe4355cd04cb7ad8fea3f26d052931e19..6e64091463c9cd1b263bcee6540efc7fb44cb1db 100644 (file)
--- a/net/queue.c
+++ b/net/queue.c
@@ -228,7 +228,7 @@ void qemu_net_queue_purge(NetQueue *queue, NetClientState *from)
     }
 }
 
-void qemu_net_queue_flush(NetQueue *queue)
+bool qemu_net_queue_flush(NetQueue *queue)
 {
     while (!QTAILQ_EMPTY(&queue->packets)) {
         NetPacket *packet;
@@ -244,7 +244,7 @@ void qemu_net_queue_flush(NetQueue *queue)
                                      packet->size);
         if (ret == 0) {
             QTAILQ_INSERT_HEAD(&queue->packets, packet, entry);
-            break;
+            return false;
         }
 
         if (packet->sent_cb) {
@@ -253,4 +253,5 @@ void qemu_net_queue_flush(NetQueue *queue)
 
         g_free(packet);
     }
+    return true;
 }

diff --git a/net/queue.h b/net/queue.h
index 9d44a9b3b87859584cea9459c1adb5421b0145a4..fc02b33915f0f93792eddb64a0bb0aac2abfa0b7 100644 (file)
--- a/net/queue.h
+++ b/net/queue.h
@@ -53,6 +53,6 @@ ssize_t qemu_net_queue_send_iov(NetQueue *queue,
                                 NetPacketSent *sent_cb);
 
 void qemu_net_queue_purge(NetQueue *queue, NetClientState *from);
-void qemu_net_queue_flush(NetQueue *queue);
+bool qemu_net_queue_flush(NetQueue *queue);
 
 #endif /* QEMU_NET_QUEUE_H */