If the host port is not open, a write() should either just return if the file is opened in non-blocking mode, or block till the host port is opened.
This is just half of the blocking/non-blocking story. The other half will be addressed when we get rid of the cpu_relax() in send_buf(). Add a fixme mentioning that case. Signed-off-by: Amit Shah <[email protected]> --- drivers/char/virtio_console.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index f33ceaa..fa616aa 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -536,6 +536,24 @@ static ssize_t port_fops_write(struct file *filp, const char __user *ubuf, port = filp->private_data; + if (!port->host_connected) { + /* + * FIXME: Also check if the vq has enough room to send + * this buffer out to the guest. Return EAGAIN or + * block in case there's no room. Currently the vq + * always has room because we only use one buffer (and + * cpu_relax()), but when send_buf() becomes + * non-spinning, we'll use more buffers. + */ + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(port->waitqueue, + port->host_connected); + if (ret < 0) + return ret; + } + count = min((size_t)(32 * 1024), count); buf = kmalloc(count, GFP_KERNEL); -- 1.6.2.5 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
