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
v4: reorder once more
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/dma-buf.c | 83 +++++++++++++++++++++++++++++++++------
include/linux/dma-buf.h | 5 +++
2 files changed, 76 insertions(+), 12 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 0aa97bb05636..95bcd2ed795b 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -660,6 +660,48 @@ 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
+ * 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;
+ int r;
+
+ might_sleep();
+ reservation_object_assert_held(attach->dmabuf->resv);
+
+ if (attach->sgt)
+ return attach->sgt;
+
+ r = dma_buf_pin(attach->dmabuf);
+ if (r)
+ return ERR_PTR(r);
+
+ sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+ if (!sg_table)
+ return 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
@@ -679,7 +721,6 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
enum dma_data_direction direction)
{
struct sg_table *sg_table;
- int r;
might_sleep();
@@ -690,21 +731,40 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
return attach->sgt;
reservation_object_lock(attach->dmabuf->resv, NULL);
- r = dma_buf_pin(attach->dmabuf);
- if (r) {
- reservation_object_unlock(attach->dmabuf->resv);
- return ERR_PTR(r);
- }
-
- sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
- if (!sg_table)
- sg_table = ERR_PTR(-ENOMEM);
+ sg_table = dma_buf_map_attachment(attach, direction);
reservation_object_unlock(attach->dmabuf->resv);
return sg_table;
}
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);
+
+ if (attach->sgt == sg_table)
+ return;
+
+ attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
+ direction);
+ dma_buf_unpin(attach->dmabuf);
+}
+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
@@ -728,8 +788,7 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
return;
reservation_object_lock(attach->dmabuf->resv, NULL);
- attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
- dma_buf_unpin(attach->dmabuf);
+ 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 425a771d229c..f7d6fc049b39 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -427,8 +427,13 @@ 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,
--
2.17.1
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