From d6258c93a7133bb2bf2ab4e91476bc0b631ba7f1 Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Tue, 5 Mar 2013 23:21:35 +0530 Subject: [PATCH] virtio-serial: make flow control explicit in virtio-console 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 Message-id: f5ec50b068c25422256e499cf4adc06d353bf394.1362505276.git.amit.shah@redhat.com Signed-off-by: Anthony Liguori --- 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 b3ee074a87..194de6431e 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 aa7d0d7fc7..f76c5058ba 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;