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>
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 3516aeb..cb5edf3 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -351,11 +351,12 @@
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 @@
unsigned long flags;
bool ret;
- spin_lock_irqsave(&port->inbuf_lock, flags);
- if (port->inbuf) {
- ret = true;
- goto out;
- }
- port->inbuf = get_inbuf(port);
- if (port->inbuf) {
- ret = true;
- goto out;
- }
ret = false;
-out:
+ spin_lock_irqsave(&port->inbuf_lock, flags);
+ port->inbuf = get_inbuf(port);
+ if (port->inbuf)
+ ret = true;
+
spin_unlock_irqrestore(&port->inbuf_lock, flags);
return ret;
}
@@ -1489,8 +1484,7 @@
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
