On 2023/12/8 1:20, Alexander Lobakin wrote:
...
> +
> +/**
> + * libie_rx_page_pool_create - create a PP with the default libie settings
> + * @bq: buffer queue struct to fill
> + * @napi: &napi_struct covering this PP (no usage outside its poll loops)
> + *
> + * Return: 0 on success, -errno on failure.
> + */
> +int libie_rx_page_pool_create(struct libie_buf_queue *bq,
> + struct napi_struct *napi)
> +{
> + struct page_pool_params pp = {
> + .flags = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV,
> + .order = LIBIE_RX_PAGE_ORDER,
> + .pool_size = bq->count,
> + .nid = NUMA_NO_NODE,
Is there a reason the NUMA_NO_NODE is used here instead of
dev_to_node(napi->dev->dev.parent)?
> + .dev = napi->dev->dev.parent,
> + .netdev = napi->dev,
> + .napi = napi,
> + .dma_dir = DMA_FROM_DEVICE,
> + .offset = LIBIE_SKB_HEADROOM,
> + };
> +
> + /* HW-writeable / syncable length per one page */
> + pp.max_len = LIBIE_RX_BUF_LEN(pp.offset);
> +
> + /* HW-writeable length per buffer */
> + bq->rx_buf_len = libie_rx_hw_len(&pp);
> + /* Buffer size to allocate */
> + bq->truesize = roundup_pow_of_two(SKB_HEAD_ALIGN(pp.offset +
> + bq->rx_buf_len));
> +
> + bq->pp = page_pool_create(&pp);
> +
> + return PTR_ERR_OR_ZERO(bq->pp);
> +}
> +EXPORT_SYMBOL_NS_GPL(libie_rx_page_pool_create, LIBIE);
> +
...
> +/**
> + * libie_rx_sync_for_cpu - synchronize or recycle buffer post DMA
> + * @buf: buffer to process
> + * @len: frame length from the descriptor
> + *
> + * Process the buffer after it's written by HW. The regular path is to
> + * synchronize DMA for CPU, but in case of no data it will be immediately
> + * recycled back to its PP.
> + *
> + * Return: true when there's data to process, false otherwise.
> + */
> +static inline bool libie_rx_sync_for_cpu(const struct libie_rx_buffer *buf,
> + u32 len)
> +{
> + struct page *page = buf->page;
> +
> + /* Very rare, but possible case. The most common reason:
> + * the last fragment contained FCS only, which was then
> + * stripped by the HW.
> + */
> + if (unlikely(!len)) {
> + page_pool_recycle_direct(page->pp, page);
> + return false;
> + }
> +
> + page_pool_dma_sync_for_cpu(page->pp, page, buf->offset, len);
Is there a reason why page_pool_dma_sync_for_cpu() is still used when
page_pool_create() is called with PP_FLAG_DMA_SYNC_DEV flag? Isn't syncing
already handled in page_pool core when when PP_FLAG_DMA_SYNC_DEV flag is
set?
> +
> + return true;
> +}
>
> /* O(1) converting i40e/ice/iavf's 8/10-bit hardware packet type to a parsed
> * bitfield struct.
>
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