virtio: console: make get_inbuf() return port->inbuf if present

Instead of pulling in a buffer from the vq each time it's called,
get_inbuf() now checks if the current active buffer, in port->inbuf is
valid.  If it is, just returns a pointer to it.  This ends up
simplifying a lot of code calling get_inbuf() since the check for
port->inbuf being valid was done by all the callers.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 8 insertions, 14 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3516aeb7f06c..cb5edf33bebf 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -351,11 +351,12 @@ fail:
 static struct port_buffer *get_inbuf(struct port *port)
 {
         struct port_buffer *buf;
-        struct virtqueue *vq;
         unsigned int len;
 
-        vq = port->in_vq;
-        buf = virtqueue_get_buf(vq, &len);
+        if (port->inbuf)
+                return port->inbuf;
+
+        buf = virtqueue_get_buf(port->in_vq, &len);
         if (buf) {
                 buf->len = len;
                 buf->offset = 0;
@@ -418,18 +419,12 @@ static bool port_has_data(struct port *port)
         unsigned long flags;
         bool ret;
 
+        ret = false;
         spin_lock_irqsave(&port->inbuf_lock, flags);
-        if (port->inbuf) {
-                ret = true;
-                goto out;
-        }
         port->inbuf = get_inbuf(port);
-        if (port->inbuf) {
+        if (port->inbuf)
                 ret = true;
-                goto out;
-        }
-        ret = false;
-out:
+
         spin_unlock_irqrestore(&port->inbuf_lock, flags);
         return ret;
 }
@@ -1489,8 +1484,7 @@ static void in_intr(struct virtqueue *vq)
                 return;
 
         spin_lock_irqsave(&port->inbuf_lock, flags);
-        if (!port->inbuf)
-                port->inbuf = get_inbuf(port);
+        port->inbuf = get_inbuf(port);
 
         /*
          * Don't queue up data when port is closed.  This condition