virtio: console: introduce a get_inbuf helper to fetch bufs from in_vq

This makes taking locks around the get_buf vq operation easier, as well
as complements the add_inbuf() operation.

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

1 files changed, 17 insertions, 4 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 1dbd46cb1a26..df45e5e9a947 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -77,6 +77,22 @@ fail:
         return NULL;
 }
 
+/* Callers should take appropriate locks */
+static void *get_inbuf(struct port *port)
+{
+        struct port_buffer *buf;
+        struct virtqueue *vq;
+        unsigned int len;
+
+        vq = port->in_vq;
+        buf = vq->vq_ops->get_buf(vq, &len);
+        if (buf) {
+                buf->len = len;
+                buf->offset = 0;
+        }
+        return buf;
+}
+
 /*
  * Create a scatter-gather list representing our input buffer and put
  * it in the queue.
@@ -138,7 +154,6 @@ static int put_chars(u32 vtermno, const char *buf, int count)
 static int get_chars(u32 vtermno, char *buf, int count)
 {
         struct port *port;
-        unsigned int len;
 
         port = &console;
 
@@ -147,10 +162,8 @@ static int get_chars(u32 vtermno, char *buf, int count)
 
         /* No more in buffer?  See if they've (re)used it. */
         if (port->inbuf->offset == port->inbuf->len) {
-                if (!port->in_vq->vq_ops->get_buf(port->in_vq, &len))
+                if (!get_inbuf(port))
                         return 0;
-                port->inbuf->offset = 0;
-                port->inbuf->len = len;
         }
 
         /* You want more than we have to give?  Well, try wanting less! */