virtio: scsi: make it clear that virtqueue_add_buf() no longer returns > 0

We simplified virtqueue_add_buf(), make it clear in the callers.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/scsi/virtio_scsi.c

@@ -215,7 +215,7 @@ static void virtscsi_ctrl_done(struct virtqueue *vq)
 static int virtscsi_kick_event(struct virtio_scsi *vscsi,
 			       struct virtio_scsi_event_node *event_node)
 {
-	int ret;
+	int err;
 	struct scatterlist sg;
 	unsigned long flags;
 
@@ -223,13 +223,14 @@ static int virtscsi_kick_event(struct virtio_scsi *vscsi,
 
 	spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags);
 
-	ret = virtqueue_add_buf(vscsi->event_vq.vq, &sg, 0, 1, event_node, GFP_ATOMIC);
-	if (ret >= 0)
+	err = virtqueue_add_buf(vscsi->event_vq.vq, &sg, 0, 1, event_node,
+				GFP_ATOMIC);
+	if (!err)
 		virtqueue_kick(vscsi->event_vq.vq);
 
 	spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags);
 
-	return ret;
+	return err;
 }
 
 static int virtscsi_kick_event_all(struct virtio_scsi *vscsi)
@@ -410,22 +411,23 @@ static int virtscsi_kick_cmd(struct virtio_scsi_target_state *tgt,
 {
 	unsigned int out_num, in_num;
 	unsigned long flags;
-	int ret;
+	int err;
+	bool needs_kick = false;
 
 	spin_lock_irqsave(&tgt->tgt_lock, flags);
 	virtscsi_map_cmd(tgt, cmd, &out_num, &in_num, req_size, resp_size);
 
 	spin_lock(&vq->vq_lock);
-	ret = virtqueue_add_buf(vq->vq, tgt->sg, out_num, in_num, cmd, gfp);
+	err = virtqueue_add_buf(vq->vq, tgt->sg, out_num, in_num, cmd, gfp);
 	spin_unlock(&tgt->tgt_lock);
-	if (ret >= 0)
-		ret = virtqueue_kick_prepare(vq->vq);
+	if (!err)
+		needs_kick = virtqueue_kick_prepare(vq->vq);
 
 	spin_unlock_irqrestore(&vq->vq_lock, flags);
 
-	if (ret > 0)
+	if (needs_kick)
 		virtqueue_notify(vq->vq);
-	return ret;
+	return err;
 }
 
 static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
@@ -467,7 +469,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
 
 	if (virtscsi_kick_cmd(tgt, &vscsi->req_vq, cmd,
 			      sizeof cmd->req.cmd, sizeof cmd->resp.cmd,
-			      GFP_ATOMIC) >= 0)
+			      GFP_ATOMIC) == 0)
 		ret = 0;
 
 out: