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 v3: move flag for invalidation support into the DMA-buf, use new attach_info structure to set the callback v4: use importer_priv field instead of mangling exporter priv. v5: drop invalidation_supported flag
Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-buf.c | 51 +++++++++++++++++++++++++++++++++------ include/linux/dma-buf.h | 30 +++++++++++++++++++++-- 2 files changed, 71 insertions(+), 10 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 95bcd2ed795b..1b5cdae68cd6 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -607,7 +607,9 @@ dma_buf_attach(const struct dma_buf_attach_info *info) 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);
@@ -651,7 +653,9 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) DMA_BIDIRECTIONAL);
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);
@@ -672,10 +676,7 @@ EXPORT_SYMBOL_GPL(dma_buf_detach); * 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. + * A mapping must be unmapped by using dma_buf_unmap_attachment(). */ struct sg_table * dma_buf_map_attachment_locked(struct dma_buf_attachment *attach, @@ -690,11 +691,22 @@ dma_buf_map_attachment_locked(struct dma_buf_attachment *attach, if (attach->sgt) return attach->sgt;
- r = dma_buf_pin(attach->dmabuf); - if (r) - return ERR_PTR(r); + if (attach->invalidate) { + /* + * Mapping a DMA-buf can trigger its invalidation, prevent + * sending this event to the caller by temporary removing + * this attachment from the list. + */ + list_del(&attach->node); + } else { + r = dma_buf_pin(attach->dmabuf); + if (r) + return ERR_PTR(r); + }
sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); + if (attach->invalidate) + list_add(&attach->node, &attach->dmabuf->attachments); if (!sg_table) return ERR_PTR(-ENOMEM);
@@ -761,7 +773,8 @@ void dma_buf_unmap_attachment_locked(struct dma_buf_attachment *attach,
attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction); - dma_buf_unpin(attach->dmabuf); + if (!attach->invalidate) + dma_buf_unpin(attach->dmabuf); } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment_locked);
@@ -793,6 +806,26 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
+/** + * 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) + attach->invalidate(attach); +} +EXPORT_SYMBOL_GPL(dma_buf_invalidate_mappings); + /** * DOC: cpu access * @@ -1205,10 +1238,12 @@ 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 f7d6fc049b39..d27e91bbd796 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -334,6 +334,9 @@ struct dma_buf { * @dev: device attached to the buffer. * @node: list of dma_buf_attachment. * @priv: exporter specific attachment data. + * @importer_priv: importer specific attachment data. + * @invalidate: invalidate callback, see &dma_buf_attach_info.invalidate for + * more information. * * This structure holds the attachment information between the dma_buf buffer * and its user device(s). The list contains one attachment struct per device @@ -350,6 +353,8 @@ struct dma_buf_attachment { struct list_head node; struct sg_table *sgt; void *priv; + void *importer_priv; + void (*invalidate)(struct dma_buf_attachment *attach); };
/** @@ -388,15 +393,35 @@ struct dma_buf_export_info {
/** * struct dma_buf_attach_info - holds information needed to attach to a dma_buf - * @dmabuf: the exported dma_buf - * @dev: the device which wants to import the attachment + * @dmabuf: the exported dma_buf + * @dev: the device which wants to import the attachment + * @importer_priv: private data of importer to this attachment + * @invalidate: optional callback provided by the importer * * This structure holds the information required to attach to a buffer. Used * with dma_buf_attach() only. + * + * Only if the invalidate callback is provided the framework can avoid pinning + * the backing store while mappings exists. + * + * This callback 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. After getting an + * invalidation callback all mappings should be destroyed by the importer using + * the normal dma_buf_unmap_attachment() function 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. */ struct dma_buf_attach_info { struct dma_buf *dmabuf; struct device *dev; + void *importer_priv; + void (*invalidate)(struct dma_buf_attachment *attach); };
/** @@ -436,6 +461,7 @@ void dma_buf_unmap_attachment_locked(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_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,