>From 7a9e7aaa30abf42879d3f13b41679513045c31ec Mon Sep 17 00:00:00 2001

From: Hans de Goede <hdegoede@redhat.com>

Date: Tue, 22 Mar 2011 16:28:41 +0100

Subject: [PATCH 18/18] spice-qemu-char: Fix flow control in client -> guest direction

In the old spice-vmc device we used to have:

last_out = virtio_serial_write(&svc->port, p, MIN(len, VMC_MAX_HOST_WRITE));

if (last_out > 0)

   ...

Now in the chardev backend we have:

last_out = MIN(len, VMC_MAX_HOST_WRITE);

qemu_chr_read(scd->chr, p, last_out);

if (last_out > 0) {

   ...

Which causes us to no longer detect if the virtio port is not ready

to receive data from us. chardev actually has a mechanism to detect this,

but it requires a separate call to qemu_chr_can_read, before calling

qemu_chr_read (which return void).

This patch uses qemu_chr_can_read to fix the flow control from client to

guest.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

---

 spice-qemu-char.c |   11 +++++------

 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/spice-qemu-char.c b/spice-qemu-char.c

index 343146c..def713a 100644

--- a/spice-qemu-char.c

+++ b/spice-qemu-char.c

@@ -38,14 +38,13 @@ static int vmc_write(SpiceCharDeviceInstance *sin, const uint8_t *buf, int len)

     while (len > 0) {

         last_out = MIN(len, VMC_MAX_HOST_WRITE);

-        qemu_chr_read(scd->chr, p, last_out);

-        if (last_out > 0) {

-            out += last_out;

-            len -= last_out;

-            p += last_out;

-        } else {

+        if (qemu_chr_can_read(scd->chr) < last_out) {

             break;

         }

+        qemu_chr_read(scd->chr, p, last_out);

+        out += last_out;

+        len -= last_out;

+        p += last_out;

     }

     dprintf(scd, 3, "%s: %lu/%zd\n", __func__, out, len + out);

-- 

1.7.3.2