linux-kernel - [PATCH v6 18/18] drm/virtio: add fence sanity check

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Date:   Tue,  2 Jul 2019 16:19:03 +0200
From:   Gerd Hoffmann <kraxel@...hat.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     olvaffe@...il.com, gurchetansingh@...omium.org,
        Gerd Hoffmann <kraxel@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        virtualization@...ts.linux-foundation.org (open list:VIRTIO GPU DRIVER),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v6 18/18] drm/virtio: add fence sanity check

Make sure we don't leak half-initialized fences outside the driver.

Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
---
 drivers/gpu/drm/virtio/virtgpu_fence.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c
index 70d6c4329778..98358ff9996c 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fence.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
@@ -41,6 +41,10 @@ bool virtio_fence_signaled(struct dma_fence *f)
 {
 	struct virtio_gpu_fence *fence = to_virtio_fence(f);
 
+	if (WARN_ON_ONCE(fence->f.seqno == 0))
+		/* leaked fence outside driver before completing
+		 * initialization with virtio_gpu_fence_emit */
+		return false;
 	if (atomic64_read(&fence->drv->last_seq) >= fence->f.seqno)
 		return true;
 	return false;
-- 
2.18.1