Each importer can now provide an invalidate_mappings callback.
This allows the exporter to provide the mappings without the need to pin the backing store.
v2: don't try to invalidate mappings when the callback is NULL, lock the reservation obj while using the attachments, add helper to set the callback
Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-buf.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 38 ++++++++++++++++++++++++++++++ 2 files changed, 98 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d78d5fc173dc..ed2b3559ba25 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -572,7 +572,9 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, if (ret) goto err_attach; } + reservation_object_lock(dmabuf->resv, NULL); list_add(&attach->node, &dmabuf->attachments); + reservation_object_unlock(dmabuf->resv);
mutex_unlock(&dmabuf->lock); return attach; @@ -598,7 +600,9 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) return;
mutex_lock(&dmabuf->lock); + reservation_object_lock(dmabuf->resv, NULL); list_del(&attach->node); + reservation_object_unlock(dmabuf->resv); if (dmabuf->ops->detach) dmabuf->ops->detach(dmabuf, attach);
@@ -632,10 +636,23 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL);
+ /* + * Mapping a DMA-buf can trigger its invalidation, prevent sending this + * event to the caller by temporary removing this attachment from the + * list. + */ + if (attach->invalidate_mappings) { + reservation_object_assert_held(attach->dmabuf->resv); + list_del(&attach->node); + } + sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); if (!sg_table) sg_table = ERR_PTR(-ENOMEM);
+ if (attach->invalidate_mappings) + list_add(&attach->node, &attach->dmabuf->attachments); + return sg_table; } EXPORT_SYMBOL_GPL(dma_buf_map_attachment); @@ -656,6 +673,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, { might_sleep();
+ if (attach->invalidate_mappings) + reservation_object_assert_held(attach->dmabuf->resv); + if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return;
@@ -664,6 +684,44 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
+/** + * dma_buf_set_invalidate_callback - set the invalidate_mappings callback + * + * @attach: [in] attachment where to set the callback + * @cb: [in] the callback to set + * + * Makes sure to take the appropriate locks when updating the invalidate + * mappings callback. + */ +void dma_buf_set_invalidate_callback(struct dma_buf_attachment *attach, + void (*cb)(struct dma_buf_attachment *)) +{ + reservation_object_lock(attach->dmabuf->resv, NULL); + attach->invalidate_mappings = cb; + reservation_object_unlock(attach->dmabuf->resv); +} +EXPORT_SYMBOL_GPL(dma_buf_set_invalidate_callback); + +/** + * dma_buf_invalidate_mappings - invalidate all mappings of this dma_buf + * + * @dmabuf: [in] buffer which mappings should be invalidated + * + * Informs all attachmenst that they need to destroy and recreated all their + * mappings. + */ +void dma_buf_invalidate_mappings(struct dma_buf *dmabuf) +{ + struct dma_buf_attachment *attach; + + reservation_object_assert_held(dmabuf->resv); + + list_for_each_entry(attach, &dmabuf->attachments, node) + if (attach->invalidate_mappings) + attach->invalidate_mappings(attach); +} +EXPORT_SYMBOL_GPL(dma_buf_invalidate_mappings); + /** * DOC: cpu access * @@ -1121,10 +1179,12 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) seq_puts(s, "\tAttached Devices:\n"); attach_count = 0;
+ reservation_object_lock(buf_obj->resv, NULL); list_for_each_entry(attach_obj, &buf_obj->attachments, node) { seq_printf(s, "\t%s\n", dev_name(attach_obj->dev)); attach_count++; } + reservation_object_unlock(buf_obj->resv);
seq_printf(s, "Total %d devices attached\n\n", attach_count); diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 085db2fee2d7..70c65fcfe1e3 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -91,6 +91,18 @@ struct dma_buf_ops { */ void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
+ /** + * @supports_mapping_invalidation: + * + * True for exporters which supports unpinned DMA-buf operation using + * the reservation lock. + * + * When attachment->invalidate_mappings is set the @map_dma_buf and + * @unmap_dma_buf callbacks can be called with the reservation lock + * held. + */ + bool supports_mapping_invalidation; + /** * @map_dma_buf: * @@ -326,6 +338,29 @@ struct dma_buf_attachment { struct device *dev; struct list_head node; void *priv; + + /** + * @invalidate_mappings: + * + * Optional callback provided by the importer of the attachment which + * must be set before mappings are created. + * + * If provided the exporter can avoid pinning the backing store while + * mappings exists. + * + * The function is called with the lock of the reservation object + * associated with the dma_buf held and the mapping function must be + * called with this lock held as well. This makes sure that no mapping + * is created concurrently with an ongoing invalidation. + * + * After the callback all existing mappings are still valid until all + * fences in the dma_bufs reservation object are signaled, but should be + * destroyed by the importer as soon as possible. + * + * New mappings can be created immediately, but can't be used before the + * exclusive fence in the dma_bufs reservation object is signaled. + */ + void (*invalidate_mappings)(struct dma_buf_attachment *attach); };
/** @@ -391,6 +426,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, enum dma_data_direction); void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, enum dma_data_direction); +void dma_buf_set_invalidate_callback(struct dma_buf_attachment *attach, + void (*cb)(struct dma_buf_attachment *)); +void dma_buf_invalidate_mappings(struct dma_buf *dma_buf); int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); int dma_buf_end_cpu_access(struct dma_buf *dma_buf,