virtio: console: add port stats for bytes received, sent and discarded
This commit adds port-specific stats for the number of bytes received,
sent and discarded. They're exposed via the debugfs interface. This
data can be used to check for data loss bugs (or disprove such claims).
It can also be used for accounting, if there's such a need.
The stats remain valid throughout the lifetime of the port. Unplugging
a port will reset the stats. The numbers are not reset across port
opens/closes.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 105181c..387fcdf 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -152,6 +152,10 @@
int chr_major;
};
+struct port_stats {
+ unsigned long bytes_sent, bytes_received, bytes_discarded;
+};
+
/* This struct holds the per-port data */
struct port {
/* Next port in the list, head is in the ports_device */
@@ -180,6 +184,13 @@
struct dentry *debugfs_file;
/*
+ * Keep count of the bytes sent, received and discarded for
+ * this port for accounting and debugging purposes. These
+ * counts are not reset across port open / close events.
+ */
+ struct port_stats stats;
+
+ /*
* The entries in this struct will be valid if this port is
* hooked up to an hvc console
*/
@@ -360,6 +371,7 @@
if (buf) {
buf->len = len;
buf->offset = 0;
+ port->stats.bytes_received += len;
}
return buf;
}
@@ -396,6 +408,7 @@
err = 0;
while (buf) {
+ port->stats.bytes_discarded += buf->len - buf->offset;
if (add_inbuf(port->in_vq, buf) < 0) {
err++;
free_buf(buf);
@@ -519,6 +532,8 @@
cpu_relax();
done:
spin_unlock_irqrestore(&port->outvq_lock, flags);
+
+ port->stats.bytes_sent += in_count;
/*
* We're expected to return the amount of data we wrote -- all
* of it
@@ -1049,6 +1064,14 @@
out_offset += snprintf(buf + out_offset, out_count - out_offset,
"outvq_full: %d\n", port->outvq_full);
out_offset += snprintf(buf + out_offset, out_count - out_offset,
+ "bytes_sent: %lu\n", port->stats.bytes_sent);
+ out_offset += snprintf(buf + out_offset, out_count - out_offset,
+ "bytes_received: %lu\n",
+ port->stats.bytes_received);
+ out_offset += snprintf(buf + out_offset, out_count - out_offset,
+ "bytes_discarded: %lu\n",
+ port->stats.bytes_discarded);
+ out_offset += snprintf(buf + out_offset, out_count - out_offset,
"is_console: %s\n",
is_console_port(port) ? "yes" : "no");
out_offset += snprintf(buf + out_offset, out_count - out_offset,
@@ -1133,6 +1156,7 @@
port->cons.ws.ws_row = port->cons.ws.ws_col = 0;
port->host_connected = port->guest_connected = false;
+ port->stats = (struct port_stats) { 0 };
port->outvq_full = false;