media: videobuf2: Stop using internal dma-buf lock

All drivers that use dma-bufs have been moved to the updated locking
specification and now dma-buf reservation is guaranteed to be locked
by importers during the mapping operations. There is no need to take
the internal dma-buf lock anymore. Remove locking from the videobuf2
memory allocators.

Acked-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221017172229.42269-21-dmitry.osipenko@collabora.com

Author: digetx

drivers/media/common/videobuf2/videobuf2-dma-contig.c

@@ -382,18 +382,12 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
 	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 {
 	struct vb2_dc_attachment *attach = db_attach->priv;
-	/* stealing dmabuf mutex to serialize map/unmap operations */
-	struct mutex *lock = &db_attach->dmabuf->lock;
 	struct sg_table *sgt;
 
-	mutex_lock(lock);
-
 	sgt = &attach->sgt;
 	/* return previously mapped sg table */
-	if (attach->dma_dir == dma_dir) {
-		mutex_unlock(lock);
+	if (attach->dma_dir == dma_dir)
 		return sgt;
-	}
 
 	/* release any previous cache */
 	if (attach->dma_dir != DMA_NONE) {
@@ -409,14 +403,11 @@ static struct sg_table *vb2_dc_dmabuf_ops_map(
 	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir,
 			    DMA_ATTR_SKIP_CPU_SYNC)) {
 		pr_err("failed to map scatterlist\n");
-		mutex_unlock(lock);
 		return ERR_PTR(-EIO);
 	}
 
 	attach->dma_dir = dma_dir;
 
-	mutex_unlock(lock);
-
 	return sgt;
 }
 

drivers/media/common/videobuf2/videobuf2-dma-sg.c

@@ -424,18 +424,12 @@ static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 {
 	struct vb2_dma_sg_attachment *attach = db_attach->priv;
-	/* stealing dmabuf mutex to serialize map/unmap operations */
-	struct mutex *lock = &db_attach->dmabuf->lock;
 	struct sg_table *sgt;
 
-	mutex_lock(lock);
-
 	sgt = &attach->sgt;
 	/* return previously mapped sg table */
-	if (attach->dma_dir == dma_dir) {
-		mutex_unlock(lock);
+	if (attach->dma_dir == dma_dir)
 		return sgt;
-	}
 
 	/* release any previous cache */
 	if (attach->dma_dir != DMA_NONE) {
@@ -446,14 +440,11 @@ static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 	/* mapping to the client with new direction */
 	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
 		pr_err("failed to map scatterlist\n");
-		mutex_unlock(lock);
 		return ERR_PTR(-EIO);
 	}
 
 	attach->dma_dir = dma_dir;
 
-	mutex_unlock(lock);
-
 	return sgt;
 }
 

drivers/media/common/videobuf2/videobuf2-vmalloc.c

@@ -267,18 +267,12 @@ static struct sg_table *vb2_vmalloc_dmabuf_ops_map(
 	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 {
 	struct vb2_vmalloc_attachment *attach = db_attach->priv;
-	/* stealing dmabuf mutex to serialize map/unmap operations */
-	struct mutex *lock = &db_attach->dmabuf->lock;
 	struct sg_table *sgt;
 
-	mutex_lock(lock);
-
 	sgt = &attach->sgt;
 	/* return previously mapped sg table */
-	if (attach->dma_dir == dma_dir) {
-		mutex_unlock(lock);
+	if (attach->dma_dir == dma_dir)
 		return sgt;
-	}
 
 	/* release any previous cache */
 	if (attach->dma_dir != DMA_NONE) {
@@ -289,14 +283,11 @@ static struct sg_table *vb2_vmalloc_dmabuf_ops_map(
 	/* mapping to the client with new direction */
 	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
 		pr_err("failed to map scatterlist\n");
-		mutex_unlock(lock);
 		return ERR_PTR(-EIO);
 	}
 
 	attach->dma_dir = dma_dir;
 
-	mutex_unlock(lock);
-
 	return sgt;
 }