Re: [PATCH 03/12] dma-buf: start caching of sg_table objects

On Fri, Apr 26, 2019 at 02:36:29PM +0200, Christian König wrote:

To allow a smooth transition from pinning buffer objects to dynamic invalidation we first start to cache the sg_table for an attachment unless the driver has implemented the explicite pin/unpin callbacks.

Signed-off-by: Christian König christian.koenig@amd.com

btw given how huge a change this is the doc update is rather thin :-)

Probably better to revise this all together, so we have a coherent documentation story between static and dynamic dma-buf attachments and what exactly that means in each case.

---

drivers/dma-buf/dma-buf.c | 24 ++++++++++++++++++++++++ include/linux/dma-buf.h | 1 + 2 files changed, 25 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 0656dcf289be..a18d10c4425a 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -610,6 +610,20 @@ dma_buf_attach(const struct dma_buf_attach_info *info) list_add(&attach->node, &dmabuf->attachments);

mutex_unlock(&dmabuf->lock);

• if (!dmabuf->ops->pin) {

• struct sg_table *sgt;
  

• sgt = dmabuf->ops->map_dma_buf(attach, DMA_BIDIRECTIONAL);
  

• if (!sgt)
  

• 	sgt = ERR_PTR(-ENOMEM);
  

• if (IS_ERR(sgt)) {
  

• 	dma_buf_detach(dmabuf, attach);
  

• 	return ERR_CAST(sgt);
  

• }
  

• attach->sgt = sgt;
  

• }
• return attach;

err_attach: @@ -632,6 +646,10 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) if (WARN_ON(!dmabuf || !attach)) return;

• if (attach->sgt)

• dmabuf->ops->unmap_dma_buf(attach, attach->sgt,
  

• 			   DMA_BIDIRECTIONAL);
  

• mutex_lock(&dmabuf->lock); list_del(&attach->node); if (dmabuf->ops->detach)

@@ -668,6 +686,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL);

• if (attach->sgt)

• return attach->sgt;
  

• reservation_object_lock(attach->dmabuf->resv, NULL); r = dma_buf_pin(attach->dmabuf); reservation_object_unlock(attach->dmabuf->resv);

@@ -701,6 +722,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return;

• if (attach->sgt == sg_table)

• return;
  

• attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 0321939b1c3d..b9d0719581cd 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -345,6 +345,7 @@ struct dma_buf_attachment { struct dma_buf *dmabuf; struct device *dev; struct list_head node;

• struct sg_table *sgt; void *priv;

};

-- 2.17.1

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