Re: [PATCH v20 02/16] dma-buf: add optional get_pci_tph() callback

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The kernel-doc comment references a non-existent callback `move_notify` in `struct dma_buf_attach_ops`.
--

--- Patch [2]: [PATCH v20 02/16] dma-buf: add optional get_pci_tph() callback ---
commit 799bc3a75b6c6b1dc555780b54878e41e3161d8b
Author: Zhiping Zhang <zhipingz@meta.com>

dma-buf: add optional get_pci_tph() callback

This commit adds an optional get_pci_tph callback to dma_buf_ops and a
corresponding wrapper function dma_buf_get_pci_tph() for importers. It
allows importers to query the exporter for PCIe TLP Processing Hint
namespaces and matching ST/PH tuples.

> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index d504c636dc294..e8314ed240d33 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
[ ... ]
> @@ -1144,6 +1146,36 @@ void dma_buf_unpin(struct dma_buf_attachment *attach)
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, "DMA_BUF");
>  
> +/**
> + * dma_buf_get_pci_tph - Retrieve PCIe TLP Processing Hint (TPH) metadata
> + * @dmabuf: DMA buffer to query
> + * @extended: false for 8-bit ST, true for 16-bit Extended ST
> + * @steering_tag: returns the raw steering tag for the requested namespace
> + * @ph: returns the TPH processing hint
> + *
> + * Wrapper for the optional &dma_buf_ops.get_pci_tph callback.
> + *
> + * Must be called with &dma_buf.resv held. Returns -EOPNOTSUPP if the
> + * exporter does not implement the callback or has no metadata for the
> + * requested namespace.
> + *
> + * The returned steering tag and processing hint are only valid until the
> + * exporter invalidates the current mapping (signalled to the importer via
> + * &dma_buf_attach_ops.move_notify). Importers must re-query after a new

[Severity: Low]
This isn't a bug, but there is no move_notify callback in
struct dma_buf_attach_ops. Should this reference the invalidate_mappings
callback instead?

> + * mapping is established following invalidation.
> + */
> +int dma_buf_get_pci_tph(struct dma_buf *dmabuf, bool extended,
> +			u16 *steering_tag, u8 *ph)

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260714104325.54444-1-fengchengwen@huawei.com?part=2