On Tue, 16 Apr 2019 20:38:33 +0200 Christian König wrote:
> Each importer can now provide an invalidate_mappings callback.
>
> This allows the exporter to provide the mappings without the need to pin
> the backing store.
>
> v2: don't try to invalidate mappings when the callback is NULL,
> lock the reservation obj while using the attachments,
> add helper to set the callback
> v3: move flag for invalidation support into the DMA-buf,
> use new attach_info structure to set the callback
> v4: use importer_priv field instead of mangling exporter priv.
> v5: drop invalidation_supported flag
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
> drivers/dma-buf/dma-buf.c | 37 +++++++++++++++++++++++++++++++++++++
> include/linux/dma-buf.h | 33 +++++++++++++++++++++++++++++++--
> 2 files changed, 68 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 83c92bfd964c..a3738fab3927 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -563,6 +563,8 @@ struct dma_buf_attachment *dma_buf_attach(const struct dma_buf_attach_info *info
>
> attach->dev = info->dev;
> attach->dmabuf = dmabuf;
> + attach->importer_priv = info->importer_priv;
> + attach->invalidate = info->invalidate;
>
> mutex_lock(&dmabuf->lock);
>
> @@ -571,7 +573,9 @@ struct dma_buf_attachment *dma_buf_attach(const struct dma_buf_attach_info *info
> if (ret)
> goto err_attach;
> }
> + reservation_object_lock(dmabuf->resv, NULL);
> list_add(&attach->node, &dmabuf->attachments);
> + reservation_object_unlock(dmabuf->resv);
>
OK, protection from resv lock is needed for attach.
> mutex_unlock(&dmabuf->lock);
>
The snippet in [PATCH 01/12] dma-buf: add dynamic caching of sg_table
is copied and pasted below:
@@ -573,6 +573,20 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
list_add(&attach->node, &dmabuf->attachments);
mutex_unlock(&dmabuf->lock);
+
+ if (!dmabuf->ops->dynamic_sgt_mapping) {
+ 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;
Looks like the protection mentioned is also needed in this case.
+ }
+
[...]
> +/**
> + * dma_buf_invalidate_mappings - invalidate all mappings of this dma_buf
> + *
> + * @dmabuf: [in] buffer which mappings should be invalidated
> + *
> + * Informs all attachmenst that they need to destroy and recreated all their
s/Informs/Inform/ s/attachmenst/attachments/ s/recreated/recreate/
> + * mappings.
> + */
> +void dma_buf_invalidate_mappings(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> +
> + reservation_object_assert_held(dmabuf->resv);
> +
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + if (attach->invalidate)
> + attach->invalidate(attach);
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_invalidate_mappings);
> +
>
BR
Hillf
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