virtio-serial: Apps should consume all data that guest sends out / Fix virtio api abuse

We cannot indicate to the guest how much data was consumed by an app for
out_bufs.  So we just have to assume the apps will consume all the data
that are handed over to them.

Fix the virtio api abuse in control_out() and handle_output().

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

3 files changed, 8 insertions, 11 deletions

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index bbbb6b86d0..caea11f3a8 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -20,14 +20,11 @@ typedef struct VirtConsole {
 
 
 /* Callback function that's called when the guest sends us data */
-static size_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
+static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
 {
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
-    ssize_t ret;
 
-    ret = qemu_chr_write(vcon->chr, buf, len);
-
-    return ret < 0 ? 0 : ret;
+    qemu_chr_write(vcon->chr, buf, len);
 }
 
 /* Readiness of the guest to accept data on a port */
diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 3053a35c39..ad44127154 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -335,7 +335,7 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq)
         copied = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, len);
 
         handle_control_message(vser, buf, copied);
-        virtqueue_push(vq, &elem, copied);
+        virtqueue_push(vq, &elem, 0);
     }
     qemu_free(buf);
     virtio_notify(vdev, vq);
@@ -379,11 +379,11 @@ static void handle_output(VirtIODevice *vdev, VirtQueue *vq)
         buf = qemu_malloc(buf_size);
         ret = iov_to_buf(elem.out_sg, elem.out_num, buf, 0, buf_size);
 
-        ret = port->info->have_data(port, buf, ret);
+        port->info->have_data(port, buf, ret);
         qemu_free(buf);
 
     next_buf:
-        virtqueue_push(vq, &elem, ret);
+        virtqueue_push(vq, &elem, 0);
     }
     virtio_notify(vdev, vq);
 }
diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
index f02387325f..62d76a25fe 100644
--- a/hw/virtio-serial.h
+++ b/hw/virtio-serial.h
@@ -136,10 +136,10 @@ struct VirtIOSerialPortInfo {
 
     /*
      * Guest wrote some data to the port. This data is handed over to
-     * the app via this callback. The app should return the number of
-     * bytes it successfully consumed.
+     * the app via this callback.  The app is supposed to consume all
+     * the data that is presented to it.
      */
-    size_t (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len);
+    void (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len);
 };
 
 /* Interface to the virtio-serial bus */