Am 28.06.2018 um 11:53 schrieb Zhang, Jerry (Junwei):
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)
Actually I wanted to remove those from the other functions as well.
WARN_ON and BUG_ON checks for NULL pointers before using them are
totally pointless because they have the same effect as a crash.
Regards,
Christian.
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,
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