Patchwork [4/4] virtio: console: add flow control

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Submitter Amit Shah
Date Feb. 4, 2013, 12:50 p.m.
Message ID <ef35e6cc166de3be38171b07cf3d5f3a786310a0.1359982059.git.amit.shah@redhat.com>
Download mbox | patch
Permalink /patch/217901/
State New
Headers show

Comments

Amit Shah - Feb. 4, 2013, 12:50 p.m.
The virtio-serial-bus already has the logic to make flow control work
properly.  Hook into the char layer's new ability to signal a backend is
writable again.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/virtio-console.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
Blue Swirl - Feb. 4, 2013, 6:28 p.m.
On Mon, Feb 4, 2013 at 12:50 PM, Amit Shah <amit.shah@redhat.com> wrote:
> The virtio-serial-bus already has the logic to make flow control work
> properly.  Hook into the char layer's new ability to signal a backend is
> writable again.
>
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> ---
>  hw/virtio-console.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/hw/virtio-console.c b/hw/virtio-console.c
> index 46072a0..0cf6072 100644
> --- a/hw/virtio-console.c
> +++ b/hw/virtio-console.c
> @@ -20,6 +20,18 @@ typedef struct VirtConsole {
>      CharDriverState *chr;
>  } VirtConsole;
>
> +/*
> + * Callback function that's called from chardevs when backend becomes
> + * writable.
> + */
> +static gboolean chr_write_unblocked(GIOChannel *chan, GIOCondition cond,
> +                                    void *opaque)
> +{
> +    VirtConsole *vcon = opaque;
> +
> +    virtio_serial_throttle_port(&vcon->port, false);
> +    return false;

FALSE since this is gboolean.

> +}
>
>  /* Callback function that's called when the guest sends us data */
>  static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
> @@ -48,6 +60,7 @@ static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
>           * do_flush_queued_data().
>           */
>          ret = 0;
> +        qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, chr_write_unblocked, vcon);
>      }
>      return ret;
>  }
> --
> 1.8.1
>
>

Patch

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index 46072a0..0cf6072 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -20,6 +20,18 @@  typedef struct VirtConsole {
     CharDriverState *chr;
 } VirtConsole;
 
+/*
+ * Callback function that's called from chardevs when backend becomes
+ * writable.
+ */
+static gboolean chr_write_unblocked(GIOChannel *chan, GIOCondition cond,
+                                    void *opaque)
+{
+    VirtConsole *vcon = opaque;
+
+    virtio_serial_throttle_port(&vcon->port, false);
+    return false;
+}
 
 /* Callback function that's called when the guest sends us data */
 static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
@@ -48,6 +60,7 @@  static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len)
          * do_flush_queued_data().
          */
         ret = 0;
+        qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, chr_write_unblocked, vcon);
     }
     return ret;
 }