drm/panfrost: Add sanity checks to submit IOCTL

So userspace can get feedback on any error conditions, instead of going
ahead and things breaking later.
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190424131355.62817-1-tomeu.vizoso@collabora.com

drivers/gpu/drm/panfrost/panfrost_drv.c

@@ -172,13 +172,27 @@ static int panfrost_ioctl_submit(struct drm_device *dev, void *data,
 {
 	struct panfrost_device *pfdev = dev->dev_private;
 	struct drm_panfrost_submit *args = data;
-	struct drm_syncobj *sync_out;
+	struct drm_syncobj *sync_out = NULL;
 	struct panfrost_job *job;
 	int ret = 0;
 
+	if (!args->jc)
+		return -EINVAL;
+
+	if (args->requirements && args->requirements != PANFROST_JD_REQ_FS)
+		return -EINVAL;
+
+	if (args->out_sync > 0) {
+		sync_out = drm_syncobj_find(file, args->out_sync);
+		if (!sync_out)
+			return -ENODEV;
+	}
+
 	job = kzalloc(sizeof(*job), GFP_KERNEL);
-	if (!job)
-		return -ENOMEM;
+	if (!job) {
+		ret = -ENOMEM;
+		goto fail_out_sync;
+	}
 
 	kref_init(&job->refcount);
 
@@ -190,25 +204,24 @@ static int panfrost_ioctl_submit(struct drm_device *dev, void *data,
 
 	ret = panfrost_copy_in_sync(dev, file, args, job);
 	if (ret)
-		goto fail;
+		goto fail_job;
 
 	ret = panfrost_lookup_bos(dev, file, args, job);
 	if (ret)
-		goto fail;
+		goto fail_job;
 
 	ret = panfrost_job_push(job);
 	if (ret)
-		goto fail;
+		goto fail_job;
 
 	/* Update the return sync object for the job */
-	sync_out = drm_syncobj_find(file, args->out_sync);
-	if (sync_out) {
+	if (sync_out)
 		drm_syncobj_replace_fence(sync_out, job->render_done_fence);
-		drm_syncobj_put(sync_out);
-	}
 
-fail:
+fail_job:
 	panfrost_job_put(job);
+fail_out_sync:
+	drm_syncobj_put(sync_out);
 
 	return ret;
 }