On Fri, Jun 01, 2018 at 02:00:19PM +0200, Christian König wrote:
> Add function variants which can be called with the reservation lock
> already held.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
I expect that we'll need this patch before patch 3 and then roll it out to
drivers doing reservation locking already, before we can add the
reservation stuff for all other callers.
> ---
> drivers/dma-buf/dma-buf.c | 60 ++++++++++++++++++++++++++++++++++++++++++-----
> include/linux/dma-buf.h | 5 ++++
> 2 files changed, 59 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 4f0708cb58a7..3371509b468e 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -606,6 +606,38 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
> }
> EXPORT_SYMBOL_GPL(dma_buf_detach);
>
> +/**
> + * dma_buf_map_attachment_locked - Maps the buffer into _device_ address space
> + * with the reservation lock held. Is a wrapper for map_dma_buf() of the
> + *
> + * Returns the scatterlist table of the attachment;
> + * dma_buf_ops.
> + * @attach: [in] attachment whose scatterlist is to be returned
> + * @direction: [in] direction of DMA transfer
> + *
> + * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
> + * on error. May return -EINTR if it is interrupted by a signal.
> + *
> + * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
_locked
Also please reference the other variants here for doc completeness.
> + * the underlying backing storage is pinned for as long as a mapping exists,
> + * therefore users/importers should not hold onto a mapping for undue amounts of
> + * time.
> + */
> +struct sg_table *
> +dma_buf_map_attachment_locked(struct dma_buf_attachment *attach,
> + enum dma_data_direction direction)
> +{
> + struct sg_table *sg_table;
> +
> + might_sleep();
Needs a lockdep_assert_held here.
> + sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
> + if (!sg_table)
> + sg_table = ERR_PTR(-ENOMEM);
> +
> + return sg_table;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_map_attachment_locked);
> +
> /**
> * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
> * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
> @@ -626,13 +658,12 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
> {
> struct sg_table *sg_table;
>
> - might_sleep();
>
> if (WARN_ON(!attach || !attach->dmabuf))
> return ERR_PTR(-EINVAL);
>
> reservation_object_lock(attach->dmabuf->resv, NULL);
> - sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
> + sg_table = dma_buf_map_attachment_locked(attach, direction);
> reservation_object_unlock(attach->dmabuf->resv);
> if (!sg_table)
> sg_table = ERR_PTR(-ENOMEM);
> @@ -641,6 +672,26 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
> }
> EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
>
> +/**
> + * dma_buf_unmap_attachment_locked - unmaps the buffer with reservation lock
> + * held, should deallocate the associated scatterlist. Is a wrapper for
> + * unmap_dma_buf() of dma_buf_ops.
> + * @attach: [in] attachment to unmap buffer from
> + * @sg_table: [in] scatterlist info of the buffer to unmap
> + * @direction: [in] direction of DMA transfer
> + *
> + * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
_locked
> + */
> +void dma_buf_unmap_attachment_locked(struct dma_buf_attachment *attach,
> + struct sg_table *sg_table,
> + enum dma_data_direction direction)
> +{
> + might_sleep();
Needs a lockdep_assert_held here.
Otherwise lgtm, but there's the big caveat of that I expect lockdep
fireworks on mass with this, but drivers not yet converted.
-Daniel
> + attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
> + direction);
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment_locked);
> +
> /**
> * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
> * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
> @@ -655,14 +706,11 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
> struct sg_table *sg_table,
> enum dma_data_direction direction)
> {
> - might_sleep();
> -
> if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
> return;
>
> reservation_object_lock(attach->dmabuf->resv, NULL);
> - attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
> - direction);
> + dma_buf_unmap_attachment_locked(attach, sg_table, direction);
> reservation_object_unlock(attach->dmabuf->resv);
> }
> EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index d2ba7a027a78..968777e8c662 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -388,8 +388,13 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags);
> struct dma_buf *dma_buf_get(int fd);
> void dma_buf_put(struct dma_buf *dmabuf);
>
> +struct sg_table *dma_buf_map_attachment_locked(struct dma_buf_attachment *,
> + enum dma_data_direction);
> struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
> enum dma_data_direction);
> +void dma_buf_unmap_attachment_locked(struct dma_buf_attachment *,
> + struct sg_table *,
> + enum dma_data_direction);
> void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
> enum dma_data_direction);
> int dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
> --
> 2.14.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
