If caching of buffers upon closing a port is not desired, delete all the buffers queued up for the port upon port close.
Signed-off-by: Amit Shah <[email protected]> --- drivers/char/virtio_console.c | 56 ++++++++++++++++++++++++++++++++++++++++ include/linux/virtio_console.h | 1 + 2 files changed, 57 insertions(+), 0 deletions(-) diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 2409330..4c9ec04 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -190,6 +190,9 @@ struct port { /* Does the Host not want to accept more data currently? */ bool host_throttled; + + /* Does the port want to cache data when disconnected? */ + bool cache_buffers; }; /* This is the very early arch-specified put chars function. */ @@ -326,6 +329,34 @@ static int add_inbuf(struct virtqueue *vq, struct port_buffer *buf) return ret; } +/* Discard any unread data this port has. Callers lockers. */ +static void flush_port_data(struct port *port) +{ + struct port_buffer *buf; + struct virtqueue *vq; + unsigned int len; + int ret; + + vq = port->in_vq; + if (port->inbuf) + buf = port->inbuf; + else + buf = vq->vq_ops->get_buf(vq, &len); + + ret = 0; + while (buf) { + if (add_inbuf(vq, buf) < 0) { + ret++; + free_buf(buf); + } + buf = vq->vq_ops->get_buf(vq, &len); + } + port->inbuf = NULL; + if (ret) + dev_warn(port->dev, "Errors adding %d buffers back to vq\n", + ret); +} + static bool port_has_data(struct port *port) { unsigned long flags; @@ -577,8 +608,18 @@ static int port_fops_release(struct inode *inode, struct file *filp) /* Notify host of port being closed */ send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0); + spin_lock_irq(&port->inbuf_lock); port->guest_connected = false; + /* + * If the port doesn't want to cache buffers while closed, + * flush the unread buffers queue + */ + if (!port->cache_buffers) + flush_port_data(port); + + spin_unlock_irq(&port->inbuf_lock); + return 0; } @@ -879,6 +920,9 @@ static void handle_control_message(struct ports_device *portdev, */ port->host_throttled = cpkt->value; break; + case VIRTIO_CONSOLE_CACHE_BUFFERS: + port->cache_buffers = cpkt->value; + break; } } @@ -923,6 +967,17 @@ static void in_intr(struct virtqueue *vq) spin_lock_irqsave(&port->inbuf_lock, flags); if (!port->inbuf) port->inbuf = get_inbuf(port); + + /* + * Don't queue up buffers if caching is disabled and port is + * closed. This condition can be reached when a console port + * is not yet connected (no tty is spawned) and the host sends + * out data to console ports. For generic serial ports, the + * host won't send data till the guest is connected. + */ + if (!port->guest_connected && !port->cache_buffers) + flush_port_data(port); + spin_unlock_irqrestore(&port->inbuf_lock, flags); wake_up_interruptible(&port->waitqueue); @@ -981,6 +1036,7 @@ static int add_port(struct ports_device *portdev, u32 id) port->host_connected = port->guest_connected = false; port->host_throttled = false; + port->cache_buffers = false; port->in_vq = portdev->in_vqs[port->id]; port->out_vq = portdev->out_vqs[port->id]; diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h index 4bd57c8..41ef890 100644 --- a/include/linux/virtio_console.h +++ b/include/linux/virtio_console.h @@ -42,6 +42,7 @@ struct virtio_console_control { #define VIRTIO_CONSOLE_PORT_OPEN 3 #define VIRTIO_CONSOLE_PORT_NAME 4 #define VIRTIO_CONSOLE_THROTTLE_PORT 5 +#define VIRTIO_CONSOLE_CACHE_BUFFERS 6 /* * This struct is put at the start of each data buffer that gets -- 1.6.2.5 _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
