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[Qemu-devel] [PATCH 1/1] virtio-serial: make flow control explicit in vi
From: |
Amit Shah |
Subject: |
[Qemu-devel] [PATCH 1/1] virtio-serial: make flow control explicit in virtio-console |
Date: |
Tue, 26 Feb 2013 11:43:50 +0530 |
virtio-console.c used to return a value less than the number of bytes
asked to be written out to a chardev backend in case the backend is not
writable. virtio-serial-bus.c then implicitly enabled flow control for
that port.
Make this explicit instead.
Signed-off-by: Amit Shah <address@hidden>
---
hw/virtio-console.c | 17 +++++++++--------
hw/virtio-serial-bus.c | 19 +------------------
2 files changed, 10 insertions(+), 26 deletions(-)
diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index b3ee074..194de64 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -47,20 +47,21 @@ static ssize_t flush_buf(VirtIOSerialPort *port, const
uint8_t *buf, size_t len)
ret = qemu_chr_fe_write(vcon->chr, buf, len);
trace_virtio_console_flush_buf(port->id, len, ret);
- if (ret < 0) {
+ if (ret <= 0) {
+ VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
+
/*
* Ideally we'd get a better error code than just -1, but
* that's what the chardev interface gives us right now. If
* we had a finer-grained message, like -EPIPE, we could close
- * this connection. Absent such error messages, the most we
- * can do is to return 0 here.
- *
- * This will prevent stray -1 values to go to
- * virtio-serial-bus.c and cause abort()s in
- * do_flush_queued_data().
+ * this connection.
*/
ret = 0;
- qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, chr_write_unblocked, vcon);
+ if (!k->is_console) {
+ virtio_serial_throttle_port(port, true);
+ qemu_chr_fe_add_watch(vcon->chr, G_IO_OUT, chr_write_unblocked,
+ vcon);
+ }
}
return ret;
}
diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index aa7d0d7..f76c505 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -172,24 +172,7 @@ static void do_flush_queued_data(VirtIOSerialPort *port,
VirtQueue *vq,
port->elem.out_sg[i].iov_base
+ port->iov_offset,
buf_size);
- if (ret < 0 && ret != -EAGAIN) {
- /* We don't handle any other type of errors here */
- abort();
- }
- if (ret == -EAGAIN || (ret >= 0 && ret < buf_size)) {
- /*
- * this is a temporary check until chardevs can signal to
- * frontends that they are writable again. This prevents
- * the console from going into throttled mode (forever)
- * if virtio-console is connected to a pty without a
- * listener. Otherwise the guest spins forever.
- * We can revert this if
- * 1: chardevs can notify frondends
- * 2: the guest driver does not spin in these cases
- */
- if (!vsc->is_console) {
- virtio_serial_throttle_port(port, true);
- }
+ if (port->throttled) {
port->iov_idx = i;
if (ret > 0) {
port->iov_offset += ret;
--
1.8.1.2