diff options
Diffstat (limited to 'drivers/dma-buf/dma-buf.c')
| -rw-r--r-- | drivers/dma-buf/dma-buf.c | 69 |
1 files changed, 56 insertions, 13 deletions
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 8c16c8c425cc..b0bc204bae14 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -916,8 +916,7 @@ static bool dma_buf_pin_on_map(struct dma_buf_attachment *attach) { return attach->dmabuf->ops->pin && - (!dma_buf_attachment_is_dynamic(attach) || - !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)); + !dma_buf_attachment_is_dynamic(attach); } /** @@ -981,7 +980,7 @@ dma_buf_pin_on_map(struct dma_buf_attachment *attach) * 3. Exporters must hold the dma-buf reservation lock when calling these * functions: * - * - dma_buf_move_notify() + * - dma_buf_invalidate_mappings() */ /** @@ -1017,9 +1016,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, if (WARN_ON(!dmabuf || !dev)) return ERR_PTR(-EINVAL); - if (WARN_ON(importer_ops && !importer_ops->move_notify)) - return ERR_PTR(-EINVAL); - attach = kzalloc_obj(*attach); if (!attach) return ERR_PTR(-ENOMEM); @@ -1130,7 +1126,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_pin, "DMA_BUF"); * * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move * any mapping of @attach again and inform the importer through - * &dma_buf_attach_ops.move_notify. + * &dma_buf_attach_ops.invalidate_mappings. */ void dma_buf_unpin(struct dma_buf_attachment *attach) { @@ -1323,24 +1319,71 @@ void dma_buf_unmap_attachment_unlocked(struct dma_buf_attachment *attach, EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment_unlocked, "DMA_BUF"); /** - * dma_buf_move_notify - notify attachments that DMA-buf is moving + * dma_buf_attach_revocable - check if a DMA-buf importer implements + * revoke semantics. + * @attach: the DMA-buf attachment to check + * + * Returns true if the DMA-buf importer can support the revoke sequence + * explained in dma_buf_invalidate_mappings() within bounded time. Meaning the + * importer implements invalidate_mappings() and ensures that unmap is called as + * a result. + */ +bool dma_buf_attach_revocable(struct dma_buf_attachment *attach) +{ + return attach->importer_ops && + attach->importer_ops->invalidate_mappings; +} +EXPORT_SYMBOL_NS_GPL(dma_buf_attach_revocable, "DMA_BUF"); + +/** + * dma_buf_invalidate_mappings - notify attachments that DMA-buf is moving * * @dmabuf: [in] buffer which is moving * * Informs all attachments that they need to destroy and recreate all their - * mappings. + * mappings. If the attachment is dynamic then the dynamic importer is expected + * to invalidate any caches it has of the mapping result and perform a new + * mapping request before allowing HW to do any further DMA. + * + * If the attachment is pinned then this informs the pinned importer that the + * underlying mapping is no longer available. Pinned importers may take this is + * as a permanent revocation and never establish new mappings so exporters + * should not trigger it lightly. + * + * Upon return importers may continue to access the DMA-buf memory. The caller + * must do two additional waits to ensure that the memory is no longer being + * accessed: + * 1) Until dma_resv_wait_timeout() retires fences the importer is allowed to + * fully access the memory. + * 2) Until the importer calls unmap it is allowed to speculatively + * read-and-discard the memory. It must not write to the memory. + * + * A caller wishing to use dma_buf_invalidate_mappings() to fully stop access to + * the DMA-buf must wait for both. Dynamic callers can often use just the first. + * + * All importers providing a invalidate_mappings() op must ensure that unmap is + * called within bounded time after the op. + * + * Pinned importers that do not support a invalidate_mappings() op will + * eventually perform unmap when they are done with the buffer, which may be an + * ubounded time from calling this function. dma_buf_attach_revocable() can be + * used to prevent such importers from attaching. + * + * Importers are free to request a new mapping in parallel as this function + * returns. */ -void dma_buf_move_notify(struct dma_buf *dmabuf) +void dma_buf_invalidate_mappings(struct dma_buf *dmabuf) { struct dma_buf_attachment *attach; dma_resv_assert_held(dmabuf->resv); list_for_each_entry(attach, &dmabuf->attachments, node) - if (attach->importer_ops) - attach->importer_ops->move_notify(attach); + if (attach->importer_ops && + attach->importer_ops->invalidate_mappings) + attach->importer_ops->invalidate_mappings(attach); } -EXPORT_SYMBOL_NS_GPL(dma_buf_move_notify, "DMA_BUF"); +EXPORT_SYMBOL_NS_GPL(dma_buf_invalidate_mappings, "DMA_BUF"); /** * DOC: cpu access |