Patchwork [1/3] virtio-serial: Let virtio-serial-bus know if all data was consumed

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Submitter Amit Shah
Date Jan. 11, 2011, 11:24 a.m.
Message ID <abc7dd602acfc544af529bfb524af0504adb011e.1294744905.git.amit.shah@redhat.com>
Download mbox | patch
Permalink /patch/78362/
State New
Headers show

Comments

Amit Shah - Jan. 11, 2011, 11:24 a.m.
The have_data() API to hand off guest data to apps using virtio-serial
so far assumed all the data was consumed.  Relax this assumption.
Future commits will allow for incomplete writes.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/virtio-console.c |    4 ++--
 hw/virtio-serial.h  |    7 ++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

Patch

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 3bd2b79..7c12230 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -20,11 +20,11 @@  typedef struct VirtConsole {
 
 
 /* Callback function that's called when the guest sends us data */
-static void flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
+static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
 {
     VirtConsole *vcon = DO_UPCAST(VirtConsole, port, port);
 
-    qemu_chr_write(vcon->chr, buf, len);
+    return qemu_chr_write(vcon->chr, buf, len);
 }
 
 /* Readiness of the guest to accept data on a port */
diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
index ff08c40..9cc0fb3 100644
--- a/hw/virtio-serial.h
+++ b/hw/virtio-serial.h
@@ -137,10 +137,11 @@  struct VirtIOSerialPortInfo {
 
     /*
      * Guest wrote some data to the port. This data is handed over to
-     * the app via this callback.  The app is supposed to consume all
-     * the data that is presented to it.
+     * the app via this callback.  The app can return a size less than
+     * 'len'.  In this case, throttling will be enabled for this port.
      */
-    void (*have_data)(VirtIOSerialPort *port, const uint8_t *buf, size_t len);
+    ssize_t (*have_data)(VirtIOSerialPort *port, const uint8_t *buf,
+                         size_t len);
 };
 
 /* Interface to the virtio-serial bus */