Re: [PATCH 1/4] dma-buf: add dma_buf_(un)map_attachment_locked variants v2

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 06/22/2018 10:11 PM, Christian König wrote:
Add function variants which can be called with the reservation lock
already held.

v2: reordered, add lockdep asserts, fix kerneldoc

Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
  drivers/dma-buf/dma-buf.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++
  include/linux/dma-buf.h   |  5 +++++
  2 files changed, 62 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 852a3928ee71..dc94e76e2e2a 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -606,6 +606,40 @@ 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_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;
+

Perhaps better to add some error check, like dma_buf_map_attachment()

WARN_ON(!attach || !attach->dmabuf)

Apart from that, it's
Reviewed-by: Junwei Zhang <Jerry.Zhang@xxxxxxx>

Jerry

+	might_sleep();
+	reservation_object_assert_held(attach->dmabuf->resv);
+
+	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
@@ -639,6 +673,29 @@ 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();
+	reservation_object_assert_held(attach->dmabuf->resv);
+
+	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
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 991787a03199..a25e754ae2f7 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -384,8 +384,13 @@ 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,

_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/dri-devel




[Index of Archives]     [Linux DRI Users]     [Linux Intel Graphics]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux