If caching of buffers upon closing a port is not desired,
delete all the buffers queued up for the port upon port
close.
This only applies to generic ports; console ports aren't
opened / closed by the chardev interface.
Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
---
drivers/char/virtio_console.c | 49 +++++++++++++++++++++++++++++++++++----
include/linux/virtio_console.h | 2 +
2 files changed, 46 insertions(+), 5 deletions(-)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index c45b987..90bb221 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -169,6 +169,9 @@ struct virtio_console_port {
/* Have we sent out a throttle request to the Host? */
bool guest_throttled;
+
+ /* Does the port want to cache data when disconnected? */
+ bool cache_buffers;
};
struct virtio_console_struct virtconsole;
@@ -501,6 +504,21 @@ static int virtconsole_release(struct inode *inode, struct file *filp)
spin_lock(&port->readbuf_list_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) {
+ struct virtio_console_port_buffer *buf, *buf2;
+
+ list_for_each_entry_safe(buf, buf2, &port->readbuf_head, list) {
+ list_del(&buf->list);
+ kfree(buf->buf);
+ kfree(buf);
+ port->nr_buffers--;
+ }
+ }
spin_unlock(&port->readbuf_list_lock);
return 0;
@@ -778,6 +796,9 @@ static void handle_control_message(struct virtio_console_port *port,
*/
port->buffer_limit = (u32)cpkt->value * 1024 / 4;
break;
+ case VIRTIO_CONSOLE_CACHE_BUFFERS:
+ port->cache_buffers = cpkt->value;
+ break;
}
}
@@ -907,7 +928,20 @@ static void virtio_console_rx_work_handler(struct work_struct *work)
* initialised.
*/
port->host_connected = true;
-
+ /*
+ * 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) {
+ kfree(buf->buf);
+ kfree(buf);
+ continue;
+ }
if (port->guest_throttled) {
kfree(buf->buf);
kfree(buf);
@@ -1058,6 +1092,8 @@ static ssize_t virtcon_port_debugfs_read(struct file *filp, char __user *ubuf,
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"nr_buffers: %u\n", port->nr_buffers);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
+ "cache_buffers: %d\n", port->cache_buffers);
+ out_offset += snprintf(buf + out_offset, out_count - out_offset,
"host_connected: %d\n", port->host_connected);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"host_throttled: %d\n", port->host_throttled);
@@ -1232,17 +1268,19 @@ static int __devinit virtcons_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
multiport = true;
vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
- vdev->config->finalize_features(vdev);
vdev->config->get(vdev, offsetof(struct virtio_console_config,
nr_ports),
&virtconsole.config.nr_ports,
sizeof(virtconsole.config.nr_ports));
}
- if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_THROTTLE)) {
+ if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_THROTTLE))
vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_THROTTLE;
- vdev->config->finalize_features(vdev);
- }
+
+ if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_CACHING))
+ vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_CACHING;
+
+ vdev->config->finalize_features(vdev);
/* Find the queues. */
/* FIXME: This is why we want to wean off hvc: we do nothing
* when input comes in. */
@@ -1294,6 +1332,7 @@ static unsigned int features[] = {
VIRTIO_CONSOLE_F_SIZE,
VIRTIO_CONSOLE_F_MULTIPORT,
VIRTIO_CONSOLE_F_THROTTLE,
+ VIRTIO_CONSOLE_F_CACHING,
};
static struct virtio_driver virtio_console = {
diff --git a/include/linux/virtio_console.h b/include/linux/virtio_console.h
index 5336a75..ce5eef2 100644
--- a/include/linux/virtio_console.h
+++ b/include/linux/virtio_console.h
@@ -14,6 +14,7 @@
#define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */
#define VIRTIO_CONSOLE_F_MULTIPORT 1 /* Does host provide multiple ports? */
#define VIRTIO_CONSOLE_F_THROTTLE 2 /* Do we throttle data to prevent OOM */
+#define VIRTIO_CONSOLE_F_CACHING 3 /* Do we cache data after port close? */
struct virtio_console_config {
/* colums of the screens */
@@ -40,6 +41,7 @@ struct virtio_console_control {
#define VIRTIO_CONSOLE_RESIZE 3
#define VIRTIO_CONSOLE_THROTTLE_PORT 4
#define VIRTIO_CONSOLE_BUFFER_LIMIT 5
+#define VIRTIO_CONSOLE_CACHE_BUFFERS 6
/*
* This struct is put in each buffer that gets passed to userspace and
--
1.6.2.5
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/virtualization
