Add optional explicit pinning callbacks instead of implicitly assume the
exporter pins the buffer when a mapping is created.
v2: move in patchset and pin the dma-buf in the old mapping code paths.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/dma-buf/dma-buf.c | 49 ++++++++++++++++++++++++++++++++++++++-
include/linux/dma-buf.h | 38 +++++++++++++++++++++++++-----
2 files changed, 80 insertions(+), 7 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 50b4c6af04c7..0656dcf289be 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -529,6 +529,41 @@ void dma_buf_put(struct dma_buf *dmabuf)
}
EXPORT_SYMBOL_GPL(dma_buf_put);
+/**
+ * dma_buf_pin - Lock down the DMA-buf
+ *
+ * @dmabuf: [in] DMA-buf to lock down.
+ *
+ * Returns:
+ * 0 on success, negative error code on failure.
+ */
+int dma_buf_pin(struct dma_buf *dmabuf)
+{
+ int ret = 0;
+
+ reservation_object_assert_held(dmabuf->resv);
+
+ if (dmabuf->ops->pin)
+ ret = dmabuf->ops->pin(dmabuf);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dma_buf_pin);
+
+/**
+ * dma_buf_unpin - Remove lock from DMA-buf
+ *
+ * @dmabuf: [in] DMA-buf to unlock.
+ */
+void dma_buf_unpin(struct dma_buf *dmabuf)
+{
+ reservation_object_assert_held(dmabuf->resv);
+
+ if (dmabuf->ops->unpin)
+ dmabuf->ops->unpin(dmabuf);
+}
+EXPORT_SYMBOL_GPL(dma_buf_unpin);
+
/**
* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
* calls attach() of dma_buf_ops to allow device-specific attach functionality
@@ -548,7 +583,8 @@ EXPORT_SYMBOL_GPL(dma_buf_put);
* accessible to @dev, and cannot be moved to a more suitable place. This is
* indicated with the error code -EBUSY.
*/
-struct dma_buf_attachment *dma_buf_attach(const struct dma_buf_attach_info *info)
+struct dma_buf_attachment *
+dma_buf_attach(const struct dma_buf_attach_info *info)
{
struct dma_buf *dmabuf = info->dmabuf;
struct dma_buf_attachment *attach;
@@ -625,12 +661,19 @@ 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();
if (WARN_ON(!attach || !attach->dmabuf))
return ERR_PTR(-EINVAL);
+ reservation_object_lock(attach->dmabuf->resv, NULL);
+ r = dma_buf_pin(attach->dmabuf);
+ reservation_object_unlock(attach->dmabuf->resv);
+ if (r)
+ return ERR_PTR(r);
+
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
if (!sg_table)
sg_table = ERR_PTR(-ENOMEM);
@@ -660,6 +703,10 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
direction);
+
+ reservation_object_lock(attach->dmabuf->resv, NULL);
+ dma_buf_unpin(attach->dmabuf);
+ 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 2c312dfd31a1..0321939b1c3d 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -51,6 +51,34 @@ struct dma_buf_attachment;
* @vunmap: [optional] unmaps a vmap from the buffer
*/
struct dma_buf_ops {
+ /**
+ * @pin:
+ *
+ * This is called by dma_buf_pin and lets the exporter know that the
+ * DMA-buf can't be moved any more.
+ *
+ * This is called with the dmabuf->resv object locked.
+ *
+ * This callback is optional.
+ *
+ * Returns:
+ *
+ * 0 on success, negative error code on failure.
+ */
+ int (*pin)(struct dma_buf *);
+
+ /**
+ * @unpin:
+ *
+ * This is called by dma_buf_unpin and lets the exporter know that the
+ * DMA-buf can be moved again.
+ *
+ * This is called with the dmabuf->resv object locked.
+ *
+ * This callback is optional.
+ */
+ void (*unpin)(struct dma_buf *);
+
/**
* @attach:
*
@@ -95,9 +123,7 @@ struct dma_buf_ops {
*
* This is called by dma_buf_map_attachment() and is used to map a
* shared &dma_buf into device address space, and it is mandatory. It
- * can only be called if @attach has been called successfully. This
- * essentially pins the DMA buffer into place, and it cannot be moved
- * any more
+ * can only be called if @attach has been called successfully.
*
* This call may sleep, e.g. when the backing storage first needs to be
* allocated, or moved to a location suitable for all currently attached
@@ -135,9 +161,6 @@ struct dma_buf_ops {
*
* This is called by dma_buf_unmap_attachment() and should unmap and
* release the &sg_table allocated in @map_dma_buf, and it is mandatory.
- * It should also unpin the backing storage if this is the last mapping
- * of the DMA buffer, it the exporter supports backing storage
- * migration.
*/
void (*unmap_dma_buf)(struct dma_buf_attachment *,
struct sg_table *,
@@ -386,6 +409,9 @@ static inline void get_dma_buf(struct dma_buf *dmabuf)
get_file(dmabuf->file);
}
+int dma_buf_pin(struct dma_buf *dmabuf);
+void dma_buf_unpin(struct dma_buf *dmabuf);
+
struct dma_buf_attachment *
dma_buf_attach(const struct dma_buf_attach_info *info);
void dma_buf_detach(struct dma_buf *dmabuf,
--
2.17.1
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