Patchwork [PATCHv2,1/3] virtio-serial-bus: use bh for unthrottling

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Submitter Alon Levy
Date April 28, 2011, 12:04 p.m.
Message ID <1303992254-4940-2-git-send-email-alevy@redhat.com>
Download mbox | patch
Permalink /patch/93209/
State New
Headers show

Comments

Alon Levy - April 28, 2011, 12:04 p.m.
Instead of calling flush_queued_data when unthrottling, schedule
a bh. That way we can return immediately to the caller, and the
flush uses the same call path as a have_data for callbackee.
---
 hw/virtio-serial-bus.c |   11 +++++++++--
 hw/virtio-serial.h     |    5 +++++
 2 files changed, 14 insertions(+), 2 deletions(-)

Patch

diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 6227379..8556e08 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -285,6 +285,13 @@  size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
     return 0;
 }
 
+static void bh_virtio_serial_flush_queued_data(void *opaque)
+{
+    VirtIOSerialPort *port = opaque;
+
+    flush_queued_data(port);
+}
+
 void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle)
 {
     if (!port) {
@@ -295,8 +302,7 @@  void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle)
     if (throttle) {
         return;
     }
-
-    flush_queued_data(port);
+    qemu_bh_schedule(port->bh);
 }
 
 /* Guest wants to notify us of some event */
@@ -724,6 +730,7 @@  static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
     bool plugging_port0;
 
     port->vser = bus->vser;
+    port->bh = qemu_bh_new(bh_virtio_serial_flush_queued_data, port);
 
     /*
      * Is the first console port we're seeing? If so, put it up at
diff --git a/hw/virtio-serial.h b/hw/virtio-serial.h
index 5eb948e..0fa03d1 100644
--- a/hw/virtio-serial.h
+++ b/hw/virtio-serial.h
@@ -119,6 +119,11 @@  struct VirtIOSerialPort {
     uint32_t iov_idx;
     uint64_t iov_offset;
 
+    /*
+     * When unthrottling we use a buttomhalf to call flush_queued_data.
+     */
+    QEMUBH *bh;
+
     /* Identify if this is a port that binds with hvc in the guest */
     uint8_t is_console;