Re: [PATCH 02/12] dma-buf: add dma_buf_(un)map_attachment_locked variants v3

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Thanks for the comments, but you are looking at a completely outdated patchset.

If you are interested in the newest one please ping me and I'm going to CC you when I send out the next version.

Christian.

Am 25.05.19 um 03:04 schrieb Hillf Danton:
On Tue, 16 Apr 2019 20:38:31 +0200 Christian König wrote:
Add function variants which can be called with the reservation lock
already held.

v2: reordered, add lockdep asserts, fix kerneldoc
v3: rebased on sgt caching

Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
  drivers/dma-buf/dma-buf.c | 63 +++++++++++++++++++++++++++++++++++++++
  include/linux/dma-buf.h   |  5 ++++
  2 files changed, 68 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 65161a82d4d5..ef480e5fb239 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -623,6 +623,43 @@ 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
Something is missing; seems to be s/of the/of the dma_buf_ops./
+ *
+ * Returns the scatterlist table of the attachment;
+ * dma_buf_ops.
Oh it is sitting here!

+ * @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.
+ *
EINTR looks impossible in the code.

+ * A mapping must be unmapped by using dma_buf_unmap_attachment_locked(). Note
+ * that 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();
+	reservation_object_assert_held(attach->dmabuf->resv);
+
+	if (attach->sgt)
+		return attach->sgt;
+
+	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);
+
Best Regards
Hillf


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