drivers/net/ethernet/sfc/rx.c

Source file repositories/reference/linux-study-clean/drivers/net/ethernet/sfc/rx.c

File Facts

System
Linux kernel
Corpus path
drivers/net/ethernet/sfc/rx.c
Extension
.c
Size
11844 bytes
Lines
411
Domain
Driver Families
Bucket
drivers/net
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

unlikely(!efx->rx_scatter)) {
		/* If this isn't an explicit discard request, either
		 * the hardware or the driver is broken.
		 */
		WARN_ON(!(len == 0 && rx_buf->flags & EFX_RX_PKT_DISCARD));
		rx_buf->flags |= EFX_RX_PKT_DISCARD;
	}

	netif_vdbg(efx, rx_status, efx->net_dev,
		   "RX queue %d received ids %x-%x len %d %s%s\n",
		   efx_rx_queue_index(rx_queue), index,
		   (index + n_frags - 1) & rx_queue->ptr_mask, len,
		   (rx_buf->flags & EFX_RX_PKT_CSUMMED) ? " [SUMMED]" : "",
		   (rx_buf->flags & EFX_RX_PKT_DISCARD) ? " [DISCARD]" : "");

	/* Discard packet, if instructed to do so.  Process the
	 * previous receive first.
	 */
	if (unlikely(rx_buf->flags & EFX_RX_PKT_DISCARD)) {
		efx_rx_flush_packet(channel);
		efx_discard_rx_packet(channel, rx_buf, n_frags);
		return;
	}

	if (n_frags == 1 && !(flags & EFX_RX_PKT_PREFIX_LEN))
		rx_buf->len = len;

	/* Release and/or sync the DMA mapping - assumes all RX buffers
	 * consumed in-order per RX queue.
	 */
	efx_sync_rx_buffer(efx, rx_buf, rx_buf->len);

	/* Prefetch nice and early so data will (hopefully) be in cache by
	 * the time we look at it.
	 */
	prefetch(efx_rx_buf_va(rx_buf));

	rx_buf->page_offset += efx->rx_prefix_size;
	rx_buf->len -= efx->rx_prefix_size;

	if (n_frags > 1) {
		/* Release/sync DMA mapping for additional fragments.
		 * Fix length for last fragment.
		 */
		unsigned int tail_frags = n_frags - 1;

		for (;;) {
			rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
			if (--tail_frags == 0)
				break;
			efx_sync_rx_buffer(efx, rx_buf, efx->rx_dma_len);
		}
		rx_buf->len = len - (n_frags - 1) * efx->rx_dma_len;
		efx_sync_rx_buffer(efx, rx_buf, rx_buf->len);
	}

	/* All fragments have been DMA-synced, so recycle pages. */
	rx_buf = efx_rx_buffer(rx_queue, index);
	efx_recycle_rx_pages(channel, rx_buf, n_frags);

	/* Pipeline receives so that we give time for packet headers to be
	 * prefetched into cache.
	 */
	efx_rx_flush_packet(channel);
	channel->rx_pkt_n_frags = n_frags;
	channel->rx_pkt_index = index;
}

static void efx_rx_deliver(struct efx_channel *channel, u8 *eh,
			   struct efx_rx_buffer *rx_buf,
			   unsigned int n_frags)
{
	struct sk_buff *skb;
	u16 hdr_len = min_t(u16, rx_buf->len, EFX_SKB_HEADERS);

	skb = efx_rx_mk_skb(channel, rx_buf, n_frags, eh, hdr_len);
	if (unlikely(skb == NULL)) {
		struct efx_rx_queue *rx_queue;

		rx_queue = efx_channel_get_rx_queue(channel);
		efx_free_rx_buffers(rx_queue, rx_buf, n_frags);
		return;
	}
	skb_record_rx_queue(skb, channel->rx_queue.core_index);

	/* Set the SKB flags */
	skb_checksum_none_assert(skb);
	if (likely(rx_buf->flags & EFX_RX_PKT_CSUMMED)) {
		skb->ip_summed = CHECKSUM_UNNECESSARY;
		skb->csum_level = !!(rx_buf->flags & EFX_RX_PKT_CSUM_LEVEL);

Annotation

Implementation Notes