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
Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-buf.c | 43 +++++++++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 28 ++++++++++++++++++++++++++++ 2 files changed, 71 insertions(+)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d2e8ca0d9427..ffaa2f9a9c2c 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -566,6 +566,7 @@ struct dma_buf_attachment *dma_buf_attach(const struct dma_buf_attach_info *info attach->dev = info->dev; attach->dmabuf = dmabuf; attach->priv = info->priv; + attach->invalidate = info->invalidate;
mutex_lock(&dmabuf->lock);
@@ -574,7 +575,9 @@ struct dma_buf_attachment *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); return attach; @@ -600,7 +603,9 @@ 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);
@@ -634,10 +639,23 @@ 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) { + 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) + list_add(&attach->node, &attach->dmabuf->attachments); + return sg_table; } EXPORT_SYMBOL_GPL(dma_buf_map_attachment); @@ -658,6 +676,9 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, { might_sleep();
+ if (attach->invalidate) + reservation_object_assert_held(attach->dmabuf->resv); + if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return;
@@ -666,6 +687,26 @@ 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 * @@ -1123,10 +1164,12 @@ 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 2c27568d44af..15dd8598bff1 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -270,6 +270,8 @@ struct dma_buf_ops { * @poll: for userspace poll support * @cb_excl: for userspace poll support * @cb_shared: for userspace poll support + * @invalidation_supported: True when the exporter supports unpinned operation + * using the reservation lock. * * This represents a shared buffer, created by calling dma_buf_export(). The * userspace representation is a normal file descriptor, which can be created by @@ -293,6 +295,7 @@ struct dma_buf { struct list_head list_node; void *priv; struct reservation_object *resv; + bool invalidation_supported;
/* poll support */ wait_queue_head_t poll; @@ -326,6 +329,28 @@ struct dma_buf_attachment { struct device *dev; struct list_head node; void *priv; + + /** + * @invalidate: + * + * Optional callback provided by the importer of the dma-buf. + * + * 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)(struct dma_buf_attachment *attach); };
/** @@ -367,6 +392,7 @@ struct dma_buf_export_info { * @dmabuf: the exported dma_buf * @dev: the device which wants to import the attachment * @priv: private data of importer to this attachment + * @invalidate: callback to use for invalidating mappings * * This structure holds the information required to attach to a buffer. Used * with dma_buf_attach() only. @@ -375,6 +401,7 @@ struct dma_buf_attach_info { struct dma_buf *dmabuf; struct device *dev; void *priv; + void (*invalidate)(struct dma_buf_attachment *attach); };
/** @@ -406,6 +433,7 @@ 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_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,