linux-kernel - [PATCH v1] drm/virtio: Factor out common dmabuf unmapping code

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Message-ID: <20241202053955.2451321-1-dmitry.osipenko@collabora.com>
Date: Mon,  2 Dec 2024 08:39:55 +0300
From: Dmitry Osipenko <dmitry.osipenko@...labora.com>
To: David Airlie <airlied@...hat.com>,
	Gerd Hoffmann <kraxel@...hat.com>,
	Gurchetan Singh <gurchetansingh@...omium.org>,
	Chia-I Wu <olvaffe@...il.com>,
	Kim Dongwon <dongwon.kim@...el.com>,
	Kasireddy Vivek <vivek.kasireddy@...el.com>
Cc: Rob Clark <robdclark@...il.com>,
	dri-devel@...ts.freedesktop.org,
	virtualization@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	kernel@...labora.com
Subject: [PATCH v1] drm/virtio: Factor out common dmabuf unmapping code

Move out dmabuf detachment and unmapping into separate function. This
removes duplicated code and there is no need to check the GEM's kref now,
since both bo->attached and bo->sgt are unset under held reservation lock.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---
 drivers/gpu/drm/virtio/virtgpu_prime.c | 35 ++++++++++++++------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c
index 33084ce1d01d..101d1a6517ae 100644
--- a/drivers/gpu/drm/virtio/virtgpu_prime.c
+++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
@@ -184,22 +184,33 @@ int virtgpu_dma_buf_import_sgt(struct virtio_gpu_mem_entry **ents,
 	return 0;
 }
 
-static void virtgpu_dma_buf_free_obj(struct drm_gem_object *obj)
+static void virtgpu_dma_buf_unmap(struct virtio_gpu_object *bo)
 {
-	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
-	struct virtio_gpu_device *vgdev = obj->dev->dev_private;
-	struct dma_buf_attachment *attach = obj->import_attach;
-	struct dma_resv *resv = attach->dmabuf->resv;
+	struct dma_buf_attachment *attach = bo->base.base.import_attach;
 
-	if (attach) {
-		dma_resv_lock(resv, NULL);
+	dma_resv_assert_held(attach->dmabuf->resv);
 
+	if (bo->created) {
 		virtio_gpu_detach_object_fenced(bo);
 
 		if (bo->sgt)
 			dma_buf_unmap_attachment(attach, bo->sgt,
 						 DMA_BIDIRECTIONAL);
 
+		bo->sgt = NULL;
+	}
+}
+
+static void virtgpu_dma_buf_free_obj(struct drm_gem_object *obj)
+{
+	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+	struct virtio_gpu_device *vgdev = obj->dev->dev_private;
+	struct dma_buf_attachment *attach = obj->import_attach;
+	struct dma_resv *resv = attach->dmabuf->resv;
+
+	if (attach) {
+		dma_resv_lock(resv, NULL);
+		virtgpu_dma_buf_unmap(bo);
 		dma_resv_unlock(resv);
 
 		dma_buf_detach(attach->dmabuf, attach);
@@ -272,15 +283,7 @@ static void virtgpu_dma_buf_move_notify(struct dma_buf_attachment *attach)
 	struct drm_gem_object *obj = attach->importer_priv;
 	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
 
-	if (bo->created && kref_read(&obj->refcount)) {
-		virtio_gpu_detach_object_fenced(bo);
-
-		if (bo->sgt)
-			dma_buf_unmap_attachment(attach, bo->sgt,
-						 DMA_BIDIRECTIONAL);
-
-		bo->sgt = NULL;
-	}
+	virtgpu_dma_buf_unmap(bo);
 }
 
 static const struct dma_buf_attach_ops virtgpu_dma_buf_attach_ops = {
-- 
2.47.0