text: /****************************************************************************
   * Driver for Solarflare network controllers and boards
   * Copyright 2005-2006 Fen Systems Ltd.
   * Copyright 2005-2013 Solarflare Communications Inc.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published
   * by the Free Software Foundation, incorporated herein by reference.
   */
  
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/slab.h>
  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include <linux/tcp.h>
  #include <linux/udp.h>
  #include <linux/prefetch.h>
  #include <linux/moduleparam.h>
  #include <linux/iommu.h>
  #include <net/ip.h>
  #include <net/checksum.h>
  #include "net_driver.h"
  #include "efx.h"
  #include "filter.h"
  #include "nic.h"
  #include "selftest.h"
  #include "workarounds.h"
  
  /* Preferred number of descriptors to fill at once */
  #define EFX_RX_PREFERRED_BATCH 8U
  
  /* Number of RX buffers to recycle pages for.  When creating the RX page recycle
   * ring, this number is divided by the number of buffers per page to calculate
   * the number of pages to store in the RX page recycle ring.
   */
  #define EFX_RECYCLE_RING_SIZE_IOMMU 4096
  #define EFX_RECYCLE_RING_SIZE_NOIOMMU (2 * EFX_RX_PREFERRED_BATCH)
  
  /* Size of buffer allocated for skb header area. */
  #define EFX_SKB_HEADERS  128u
  
  /* This is the percentage fill level below which new RX descriptors
   * will be added to the RX descriptor ring.
   */
  static unsigned int rx_refill_threshold;
  
  /* Each packet can consume up to ceil(max_frame_len / buffer_size) buffers */
  #define EFX_RX_MAX_FRAGS DIV_ROUND_UP(EFX_MAX_FRAME_LEN(EFX_MAX_MTU), \
  				      EFX_RX_USR_BUF_SIZE)
  
  /*
   * RX maximum head room required.
   *
   * This must be at least 1 to prevent overflow, plus one packet-worth
   * to allow pipelined receives.
   */
  #define EFX_RXD_HEAD_ROOM (1 + EFX_RX_MAX_FRAGS)
  
  static inline u8 *efx_rx_buf_va(struct efx_rx_buffer *buf)
  {
  	return page_address(buf->page) + buf->page_offset;
  }
  
  static inline u32 efx_rx_buf_hash(struct efx_nic *efx, const u8 *eh)
  {
  #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
  	return __le32_to_cpup((const __le32 *)(eh + efx->rx_packet_hash_offset));
  #else
  	const u8 *data = eh + efx->rx_packet_hash_offset;
  	return (u32)data[0]	  |
  	       (u32)data[1] << 8  |
  	       (u32)data[2] << 16 |
  	       (u32)data[3] << 24;
  #endif
  }
  
  static inline struct efx_rx_buffer *
  efx_rx_buf_next(struct efx_rx_queue *rx_queue, struct efx_rx_buffer *rx_buf)
  {
  	if (unlikely(rx_buf == efx_rx_buffer(rx_queue, rx_queue->ptr_mask)))
  		return efx_rx_buffer(rx_queue, 0);
  	else
  		return rx_buf + 1;
  }
  
  static inline void efx_sync_rx_buffer(struct efx_nic *efx,
  				      struct efx_rx_buffer *rx_buf,
  				      unsigned int len)
  {
  	dma_sync_single_for_cpu(&efx->pci_dev->dev, rx_buf->dma_addr, len,
  				DMA_FROM_DEVICE);
  }
  
  void efx_rx_config_page_split(struct efx_nic *efx)
  {
  	efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + efx->rx_ip_align,
  				      EFX_RX_BUF_ALIGNMENT);
  	efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
  		((PAGE_SIZE - sizeof(struct efx_rx_page_state)) /
  		 efx->rx_page_buf_step);
  	efx->rx_buffer_truesize = (PAGE_SIZE << efx->rx_buffer_order) /
  		efx->rx_bufs_per_page;
  	efx->rx_pages_per_batch = DIV_ROUND_UP(EFX_RX_PREFERRED_BATCH,
  					       efx->rx_bufs_per_page);
  }
  
  /* Check the RX page recycle ring for a page that can be reused. */
  static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	struct page *page;
  	struct efx_rx_page_state *state;
  	unsigned index;
  
  	index = rx_queue->page_remove & rx_queue->page_ptr_mask;
  	page = rx_queue->page_ring[index];
  	if (page == NULL)
  		return NULL;
  
  	rx_queue->page_ring[index] = NULL;
  	/* page_remove cannot exceed page_add. */
  	if (rx_queue->page_remove != rx_queue->page_add)
  		++rx_queue->page_remove;
  
  	/* If page_count is 1 then we hold the only reference to this page. */
  	if (page_count(page) == 1) {
  		++rx_queue->page_recycle_count;
  		return page;
  	} else {
  		state = page_address(page);
  		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
  			       PAGE_SIZE << efx->rx_buffer_order,
  			       DMA_FROM_DEVICE);
  		put_page(page);
  		++rx_queue->page_recycle_failed;
  	}
  
  	return NULL;
  }
  
  /**
   * efx_init_rx_buffers - create EFX_RX_BATCH page-based RX buffers
   *
   * @rx_queue:		Efx RX queue
   *
   * This allocates a batch of pages, maps them for DMA, and populates
   * struct efx_rx_buffers for each one. Return a negative error code or
   * 0 on success. If a single page can be used for multiple buffers,
   * then the page will either be inserted fully, or not at all.
   */
  static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue, bool atomic)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	struct efx_rx_buffer *rx_buf;
  	struct page *page;
  	unsigned int page_offset;
  	struct efx_rx_page_state *state;
  	dma_addr_t dma_addr;
  	unsigned index, count;
  
  	count = 0;
  	do {
  		page = efx_reuse_page(rx_queue);
  		if (page == NULL) {
  			page = alloc_pages(__GFP_COLD | __GFP_COMP |
  					   (atomic ? GFP_ATOMIC : GFP_KERNEL),
  					   efx->rx_buffer_order);
  			if (unlikely(page == NULL))
  				return -ENOMEM;
  			dma_addr =
  				dma_map_page(&efx->pci_dev->dev, page, 0,
  					     PAGE_SIZE << efx->rx_buffer_order,
  					     DMA_FROM_DEVICE);
  			if (unlikely(dma_mapping_error(&efx->pci_dev->dev,
  						       dma_addr))) {
  				__free_pages(page, efx->rx_buffer_order);
  				return -EIO;
  			}
  			state = page_address(page);
  			state->dma_addr = dma_addr;
  		} else {
  			state = page_address(page);
  			dma_addr = state->dma_addr;
  		}
  
  		dma_addr += sizeof(struct efx_rx_page_state);
  		page_offset = sizeof(struct efx_rx_page_state);
  
  		do {
  			index = rx_queue->added_count & rx_queue->ptr_mask;
  			rx_buf = efx_rx_buffer(rx_queue, index);
  			rx_buf->dma_addr = dma_addr + efx->rx_ip_align;
  			rx_buf->page = page;
  			rx_buf->page_offset = page_offset + efx->rx_ip_align;
  			rx_buf->len = efx->rx_dma_len;
  			rx_buf->flags = 0;
  			++rx_queue->added_count;
  			get_page(page);
  			dma_addr += efx->rx_page_buf_step;
  			page_offset += efx->rx_page_buf_step;
  		} while (page_offset + efx->rx_page_buf_step <= PAGE_SIZE);
  
  		rx_buf->flags = EFX_RX_BUF_LAST_IN_PAGE;
  	} while (++count < efx->rx_pages_per_batch);
  
  	return 0;
  }
  
  /* Unmap a DMA-mapped page.  This function is only called for the final RX
   * buffer in a page.
   */
  static void efx_unmap_rx_buffer(struct efx_nic *efx,
  				struct efx_rx_buffer *rx_buf)
  {
  	struct page *page = rx_buf->page;
  
  	if (page) {
  		struct efx_rx_page_state *state = page_address(page);
  		dma_unmap_page(&efx->pci_dev->dev,
  			       state->dma_addr,
  			       PAGE_SIZE << efx->rx_buffer_order,
  			       DMA_FROM_DEVICE);
  	}
  }
  
  static void efx_free_rx_buffers(struct efx_rx_queue *rx_queue,
  				struct efx_rx_buffer *rx_buf,
  				unsigned int num_bufs)
  {
  	do {
  		if (rx_buf->page) {
  			put_page(rx_buf->page);
  			rx_buf->page = NULL;
  		}
  		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
  	} while (--num_bufs);
  }
  
  /* Attempt to recycle the page if there is an RX recycle ring; the page can
   * only be added if this is the final RX buffer, to prevent pages being used in
   * the descriptor ring and appearing in the recycle ring simultaneously.
   */
  static void efx_recycle_rx_page(struct efx_channel *channel,
  				struct efx_rx_buffer *rx_buf)
  {
  	struct page *page = rx_buf->page;
  	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
  	struct efx_nic *efx = rx_queue->efx;
  	unsigned index;
  
  	/* Only recycle the page after processing the final buffer. */
  	if (!(rx_buf->flags & EFX_RX_BUF_LAST_IN_PAGE))
  		return;
  
  	index = rx_queue->page_add & rx_queue->page_ptr_mask;
  	if (rx_queue->page_ring[index] == NULL) {
  		unsigned read_index = rx_queue->page_remove &
  			rx_queue->page_ptr_mask;
  
  		/* The next slot in the recycle ring is available, but
  		 * increment page_remove if the read pointer currently
  		 * points here.
  		 */
  		if (read_index == index)
  			++rx_queue->page_remove;
  		rx_queue->page_ring[index] = page;
  		++rx_queue->page_add;
  		return;
  	}
  	++rx_queue->page_recycle_full;
  	efx_unmap_rx_buffer(efx, rx_buf);
  	put_page(rx_buf->page);
  }
  
  static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue,
  			       struct efx_rx_buffer *rx_buf)
  {
  	/* Release the page reference we hold for the buffer. */
  	if (rx_buf->page)
  		put_page(rx_buf->page);
  
  	/* If this is the last buffer in a page, unmap and free it. */
  	if (rx_buf->flags & EFX_RX_BUF_LAST_IN_PAGE) {
  		efx_unmap_rx_buffer(rx_queue->efx, rx_buf);
  		efx_free_rx_buffers(rx_queue, rx_buf, 1);
  	}
  	rx_buf->page = NULL;
  }
  
  /* Recycle the pages that are used by buffers that have just been received. */
  static void efx_recycle_rx_pages(struct efx_channel *channel,
  				 struct efx_rx_buffer *rx_buf,
  				 unsigned int n_frags)
  {
  	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
  
  	do {
  		efx_recycle_rx_page(channel, rx_buf);
  		rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
  	} while (--n_frags);
  }
  
  static void efx_discard_rx_packet(struct efx_channel *channel,
  				  struct efx_rx_buffer *rx_buf,
  				  unsigned int n_frags)
  {
  	struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);
  
  	efx_recycle_rx_pages(channel, rx_buf, n_frags);
  
  	efx_free_rx_buffers(rx_queue, rx_buf, n_frags);
  }
  
  /**
   * efx_fast_push_rx_descriptors - push new RX descriptors quickly
   * @rx_queue:		RX descriptor queue
   *
   * This will aim to fill the RX descriptor queue up to
   * @rx_queue->@max_fill. If there is insufficient atomic
   * memory to do so, a slow fill will be scheduled.
   *
   * The caller must provide serialisation (none is used here). In practise,
   * this means this function must run from the NAPI handler, or be called
   * when NAPI is disabled.
   */
  void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue, bool atomic)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	unsigned int fill_level, batch_size;
  	int space, rc = 0;
  
  	if (!rx_queue->refill_enabled)
  		return;
  
  	/* Calculate current fill level, and exit if we don't need to fill */
  	fill_level = (rx_queue->added_count - rx_queue->removed_count);
  	EFX_WARN_ON_ONCE_PARANOID(fill_level > rx_queue->efx->rxq_entries);
  	if (fill_level >= rx_queue->fast_fill_trigger)
  		goto out;
  
  	/* Record minimum fill level */
  	if (unlikely(fill_level < rx_queue->min_fill)) {
  		if (fill_level)
  			rx_queue->min_fill = fill_level;
  	}
  
  	batch_size = efx->rx_pages_per_batch * efx->rx_bufs_per_page;
  	space = rx_queue->max_fill - fill_level;
  	EFX_WARN_ON_ONCE_PARANOID(space < batch_size);
  
  	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
  		   "RX queue %d fast-filling descriptor ring from"
  		   " level %d to level %d\n",
  		   efx_rx_queue_index(rx_queue), fill_level,
  		   rx_queue->max_fill);
  
  
  	do {
  		rc = efx_init_rx_buffers(rx_queue, atomic);
  		if (unlikely(rc)) {
  			/* Ensure that we don't leave the rx queue empty */
  			if (rx_queue->added_count == rx_queue->removed_count)
  				efx_schedule_slow_fill(rx_queue);
  			goto out;
  		}
  	} while ((space -= batch_size) >= batch_size);
  
  	netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
  		   "RX queue %d fast-filled descriptor ring "
  		   "to level %d\n", efx_rx_queue_index(rx_queue),
  		   rx_queue->added_count - rx_queue->removed_count);
  
   out:
  	if (rx_queue->notified_count != rx_queue->added_count)
  		efx_nic_notify_rx_desc(rx_queue);
  }
  
  void efx_rx_slow_fill(unsigned long context)
  {
  	struct efx_rx_queue *rx_queue = (struct efx_rx_queue *)context;
  
  	/* Post an event to cause NAPI to run and refill the queue */
  	efx_nic_generate_fill_event(rx_queue);
  	++rx_queue->slow_fill_count;
  }
  
  static void efx_rx_packet__check_len(struct efx_rx_queue *rx_queue,
  				     struct efx_rx_buffer *rx_buf,
  				     int len)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	unsigned max_len = rx_buf->len - efx->type->rx_buffer_padding;
  
  	if (likely(len <= max_len))
  		return;
  
  	/* The packet must be discarded, but this is only a fatal error
  	 * if the caller indicated it was
  	 */
  	rx_buf->flags |= EFX_RX_PKT_DISCARD;
  
  	if (net_ratelimit())
  		netif_err(efx, rx_err, efx->net_dev,
  			  "RX queue %d overlength RX event (%#x > %#x)\n",
  			  efx_rx_queue_index(rx_queue), len, max_len);
  
  	efx_rx_queue_channel(rx_queue)->n_rx_overlength++;
  }
  
  /* Pass a received packet up through GRO.  GRO can handle pages
   * regardless of checksum state and skbs with a good checksum.
   */
  static void
  efx_rx_packet_gro(struct efx_channel *channel, struct efx_rx_buffer *rx_buf,
  		  unsigned int n_frags, u8 *eh)
  {
  	struct napi_struct *napi = &channel->napi_str;
  	gro_result_t gro_result;
  	struct efx_nic *efx = channel->efx;
  	struct sk_buff *skb;
  
  	skb = napi_get_frags(napi);
  	if (unlikely(!skb)) {
  		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;
  	}
  
  	if (efx->net_dev->features & NETIF_F_RXHASH)
  		skb_set_hash(skb, efx_rx_buf_hash(efx, eh),
  			     PKT_HASH_TYPE_L3);
  	skb->ip_summed = ((rx_buf->flags & EFX_RX_PKT_CSUMMED) ?
  			  CHECKSUM_UNNECESSARY : CHECKSUM_NONE);
  	skb->csum_level = !!(rx_buf->flags & EFX_RX_PKT_CSUM_LEVEL);
  
  	for (;;) {
  		skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags,
  				   rx_buf->page, rx_buf->page_offset,
  				   rx_buf->len);
  		rx_buf->page = NULL;
  		skb->len += rx_buf->len;
  		if (skb_shinfo(skb)->nr_frags == n_frags)
  			break;
  
  		rx_buf = efx_rx_buf_next(&channel->rx_queue, rx_buf);
  	}
  
  	skb->data_len = skb->len;
  	skb->truesize += n_frags * efx->rx_buffer_truesize;
  
  	skb_record_rx_queue(skb, channel->rx_queue.core_index);
  
  	gro_result = napi_gro_frags(napi);
  	if (gro_result != GRO_DROP)
  		channel->irq_mod_score += 2;
  }
  
  /* Allocate and construct an SKB around page fragments */
  static struct sk_buff *efx_rx_mk_skb(struct efx_channel *channel,
  				     struct efx_rx_buffer *rx_buf,
  				     unsigned int n_frags,
  				     u8 *eh, int hdr_len)
  {
  	struct efx_nic *efx = channel->efx;
  	struct sk_buff *skb;
  
  	/* Allocate an SKB to store the headers */
  	skb = netdev_alloc_skb(efx->net_dev,
  			       efx->rx_ip_align + efx->rx_prefix_size +
  			       hdr_len);
  	if (unlikely(skb == NULL)) {
  		atomic_inc(&efx->n_rx_noskb_drops);
  		return NULL;
  	}
  
  	EFX_WARN_ON_ONCE_PARANOID(rx_buf->len < hdr_len);
  
  	memcpy(skb->data + efx->rx_ip_align, eh - efx->rx_prefix_size,
  	       efx->rx_prefix_size + hdr_len);
  	skb_reserve(skb, efx->rx_ip_align + efx->rx_prefix_size);
  	__skb_put(skb, hdr_len);
  
  	/* Append the remaining page(s) onto the frag list */
  	if (rx_buf->len > hdr_len) {
  		rx_buf->page_offset += hdr_len;
  		rx_buf->len -= hdr_len;
  
  		for (;;) {
  			skb_fill_page_desc(skb, skb_shinfo(skb)->nr_frags,
  					   rx_buf->page, rx_buf->page_offset,
  					   rx_buf->len);
  			rx_buf->page = NULL;
  			skb->len += rx_buf->len;
  			skb->data_len += rx_buf->len;
  			if (skb_shinfo(skb)->nr_frags == n_frags)
  				break;
  
  			rx_buf = efx_rx_buf_next(&channel->rx_queue, rx_buf);
  		}
  	} else {
  		__free_pages(rx_buf->page, efx->rx_buffer_order);
  		rx_buf->page = NULL;
  		n_frags = 0;
  	}
  
  	skb->truesize += n_frags * efx->rx_buffer_truesize;
  
  	/* Move past the ethernet header */
  	skb->protocol = eth_type_trans(skb, efx->net_dev);
  
  	skb_mark_napi_id(skb, &channel->napi_str);
  
  	return skb;
  }
  
  void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
  		   unsigned int n_frags, unsigned int len, u16 flags)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	struct efx_channel *channel = efx_rx_queue_channel(rx_queue);
  	struct efx_rx_buffer *rx_buf;
  
  	rx_queue->rx_packets++;
  
  	rx_buf = efx_rx_buffer(rx_queue, index);
  	rx_buf->flags |= flags;
  
  	/* Validate the number of fragments and completed length */
  	if (n_frags == 1) {
  		if (!(flags & EFX_RX_PKT_PREFIX_LEN))
  			efx_rx_packet__check_len(rx_queue, rx_buf, len);
  	} else if (unlikely(n_frags > EFX_RX_MAX_FRAGS) ||
  		   unlikely(len <= (n_frags - 1) * efx->rx_dma_len) ||
  		   unlikely(len > n_frags * efx->rx_dma_len) ||
  		   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);
  	}
  
  	efx_rx_skb_attach_timestamp(channel, skb);
  
  	if (channel->type->receive_skb)
  		if (channel->type->receive_skb(channel, skb))
  			return;
  
  	/* Pass the packet up */
  	netif_receive_skb(skb);
  }
  
  /* Handle a received packet.  Second half: Touches packet payload. */
  void __efx_rx_packet(struct efx_channel *channel)
  {
  	struct efx_nic *efx = channel->efx;
  	struct efx_rx_buffer *rx_buf =
  		efx_rx_buffer(&channel->rx_queue, channel->rx_pkt_index);
  	u8 *eh = efx_rx_buf_va(rx_buf);
  
  	/* Read length from the prefix if necessary.  This already
  	 * excludes the length of the prefix itself.
  	 */
  	if (rx_buf->flags & EFX_RX_PKT_PREFIX_LEN)
  		rx_buf->len = le16_to_cpup((__le16 *)
  					   (eh + efx->rx_packet_len_offset));
  
  	/* If we're in loopback test, then pass the packet directly to the
  	 * loopback layer, and free the rx_buf here
  	 */
  	if (unlikely(efx->loopback_selftest)) {
  		struct efx_rx_queue *rx_queue;
  
  		efx_loopback_rx_packet(efx, eh, rx_buf->len);
  		rx_queue = efx_channel_get_rx_queue(channel);
  		efx_free_rx_buffers(rx_queue, rx_buf,
  				    channel->rx_pkt_n_frags);
  		goto out;
  	}
  
  	if (unlikely(!(efx->net_dev->features & NETIF_F_RXCSUM)))
  		rx_buf->flags &= ~EFX_RX_PKT_CSUMMED;
  
  	if ((rx_buf->flags & EFX_RX_PKT_TCP) && !channel->type->receive_skb)
  		efx_rx_packet_gro(channel, rx_buf, channel->rx_pkt_n_frags, eh);
  	else
  		efx_rx_deliver(channel, eh, rx_buf, channel->rx_pkt_n_frags);
  out:
  	channel->rx_pkt_n_frags = 0;
  }
  
  int efx_probe_rx_queue(struct efx_rx_queue *rx_queue)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	unsigned int entries;
  	int rc;
  
  	/* Create the smallest power-of-two aligned ring */
  	entries = max(roundup_pow_of_two(efx->rxq_entries), EFX_MIN_DMAQ_SIZE);
  	EFX_WARN_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE);
  	rx_queue->ptr_mask = entries - 1;
  
  	netif_dbg(efx, probe, efx->net_dev,
  		  "creating RX queue %d size %#x mask %#x\n",
  		  efx_rx_queue_index(rx_queue), efx->rxq_entries,
  		  rx_queue->ptr_mask);
  
  	/* Allocate RX buffers */
  	rx_queue->buffer = kcalloc(entries, sizeof(*rx_queue->buffer),
  				   GFP_KERNEL);
  	if (!rx_queue->buffer)
  		return -ENOMEM;
  
  	rc = efx_nic_probe_rx(rx_queue);
  	if (rc) {
  		kfree(rx_queue->buffer);
  		rx_queue->buffer = NULL;
  	}
  
  	return rc;
  }
  
  static void efx_init_rx_recycle_ring(struct efx_nic *efx,
  				     struct efx_rx_queue *rx_queue)
  {
  	unsigned int bufs_in_recycle_ring, page_ring_size;
  
  	/* Set the RX recycle ring size */
  #ifdef CONFIG_PPC64
  	bufs_in_recycle_ring = EFX_RECYCLE_RING_SIZE_IOMMU;
  #else
  	if (iommu_present(&pci_bus_type))
  		bufs_in_recycle_ring = EFX_RECYCLE_RING_SIZE_IOMMU;
  	else
  		bufs_in_recycle_ring = EFX_RECYCLE_RING_SIZE_NOIOMMU;
  #endif /* CONFIG_PPC64 */
  
  	page_ring_size = roundup_pow_of_two(bufs_in_recycle_ring /
  					    efx->rx_bufs_per_page);
  	rx_queue->page_ring = kcalloc(page_ring_size,
  				      sizeof(*rx_queue->page_ring), GFP_KERNEL);
  	rx_queue->page_ptr_mask = page_ring_size - 1;
  }
  
  void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
  {
  	struct efx_nic *efx = rx_queue->efx;
  	unsigned int max_fill, trigger, max_trigger;
  
  	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
  		  "initialising RX queue %d\n", efx_rx_queue_index(rx_queue));
  
  	/* Initialise ptr fields */
  	rx_queue->added_count = 0;
  	rx_queue->notified_count = 0;
  	rx_queue->removed_count = 0;
  	rx_queue->min_fill = -1U;
  	efx_init_rx_recycle_ring(efx, rx_queue);
  
  	rx_queue->page_remove = 0;
  	rx_queue->page_add = rx_queue->page_ptr_mask + 1;
  	rx_queue->page_recycle_count = 0;
  	rx_queue->page_recycle_failed = 0;
  	rx_queue->page_recycle_full = 0;
  
  	/* Initialise limit fields */
  	max_fill = efx->rxq_entries - EFX_RXD_HEAD_ROOM;
  	max_trigger =
  		max_fill - efx->rx_pages_per_batch * efx->rx_bufs_per_page;
  	if (rx_refill_threshold != 0) {
  		trigger = max_fill * min(rx_refill_threshold, 100U) / 100U;
  		if (trigger > max_trigger)
  			trigger = max_trigger;
  	} else {
  		trigger = max_trigger;
  	}
  
  	rx_queue->max_fill = max_fill;
  	rx_queue->fast_fill_trigger = trigger;
  	rx_queue->refill_enabled = true;
  
  	/* Set up RX descriptor ring */
  	efx_nic_init_rx(rx_queue);
  }
  
  void efx_fini_rx_queue(struct efx_rx_queue *rx_queue)
  {
  	int i;
  	struct efx_nic *efx = rx_queue->efx;
  	struct efx_rx_buffer *rx_buf;
  
  	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
  		  "shutting down RX queue %d\n", efx_rx_queue_index(rx_queue));
  
  	del_timer_sync(&rx_queue->slow_fill);
  
  	/* Release RX buffers from the current read ptr to the write ptr */
  	if (rx_queue->buffer) {
  		for (i = rx_queue->removed_count; i < rx_queue->added_count;
  		     i++) {
  			unsigned index = i & rx_queue->ptr_mask;
  			rx_buf = efx_rx_buffer(rx_queue, index);
  			efx_fini_rx_buffer(rx_queue, rx_buf);
  		}
  	}
  
  	/* Unmap and release the pages in the recycle ring. Remove the ring. */
  	for (i = 0; i <= rx_queue->page_ptr_mask; i++) {
  		struct page *page = rx_queue->page_ring[i];
  		struct efx_rx_page_state *state;
  
  		if (page == NULL)
  			continue;
  
  		state = page_address(page);
  		dma_unmap_page(&efx->pci_dev->dev, state->dma_addr,
  			       PAGE_SIZE << efx->rx_buffer_order,
  			       DMA_FROM_DEVICE);
  		put_page(page);
  	}
  	kfree(rx_queue->page_ring);
  	rx_queue->page_ring = NULL;
  }
  
  void efx_remove_rx_queue(struct efx_rx_queue *rx_queue)
  {
  	netif_dbg(rx_queue->efx, drv, rx_queue->efx->net_dev,
  		  "destroying RX queue %d\n", efx_rx_queue_index(rx_queue));
  
  	efx_nic_remove_rx(rx_queue);
  
  	kfree(rx_queue->buffer);
  	rx_queue->buffer = NULL;
  }
  
  
  module_param(rx_refill_threshold, uint, 0444);
  MODULE_PARM_DESC(rx_refill_threshold,
  		 "RX descriptor ring refill threshold (%)");
  
  #ifdef CONFIG_RFS_ACCEL
  
  int efx_filter_rfs(struct net_device *net_dev, const struct sk_buff *skb,
  		   u16 rxq_index, u32 flow_id)
  {
  	struct efx_nic *efx = netdev_priv(net_dev);
  	struct efx_channel *channel;
  	struct efx_filter_spec spec;
  	struct flow_keys fk;
  	int rc;
  
  	if (flow_id == RPS_FLOW_ID_INVALID)
  		return -EINVAL;
  
  	if (!skb_flow_dissect_flow_keys(skb, &fk, 0))
  		return -EPROTONOSUPPORT;
  
  	if (fk.basic.n_proto != htons(ETH_P_IP) && fk.basic.n_proto != htons(ETH_P_IPV6))
  		return -EPROTONOSUPPORT;
  	if (fk.control.flags & FLOW_DIS_IS_FRAGMENT)
  		return -EPROTONOSUPPORT;
  
  	efx_filter_init_rx(&spec, EFX_FILTER_PRI_HINT,
  			   efx->rx_scatter ? EFX_FILTER_FLAG_RX_SCATTER : 0,
  			   rxq_index);
  	spec.match_flags =
  		EFX_FILTER_MATCH_ETHER_TYPE | EFX_FILTER_MATCH_IP_PROTO |
  		EFX_FILTER_MATCH_LOC_HOST | EFX_FILTER_MATCH_LOC_PORT |
  		EFX_FILTER_MATCH_REM_HOST | EFX_FILTER_MATCH_REM_PORT;
  	spec.ether_type = fk.basic.n_proto;
  	spec.ip_proto = fk.basic.ip_proto;
  
  	if (fk.basic.n_proto == htons(ETH_P_IP)) {
  		spec.rem_host[0] = fk.addrs.v4addrs.src;
  		spec.loc_host[0] = fk.addrs.v4addrs.dst;
  	} else {
  		memcpy(spec.rem_host, &fk.addrs.v6addrs.src, sizeof(struct in6_addr));
  		memcpy(spec.loc_host, &fk.addrs.v6addrs.dst, sizeof(struct in6_addr));
  	}
  
  	spec.rem_port = fk.ports.src;
  	spec.loc_port = fk.ports.dst;
  
  	rc = efx->type->filter_rfs_insert(efx, &spec);
  	if (rc < 0)
  		return rc;
  
  	/* Remember this so we can check whether to expire the filter later */
  	channel = efx_get_channel(efx, rxq_index);
  	channel->rps_flow_id[rc] = flow_id;
  	++channel->rfs_filters_added;
  
  	if (spec.ether_type == htons(ETH_P_IP))
  		netif_info(efx, rx_status, efx->net_dev,
  			   "steering %s %pI4:%u:%pI4:%u to queue %u [flow %u filter %d]\n",
  			   (spec.ip_proto == IPPROTO_TCP) ? "TCP" : "UDP",
  			   spec.rem_host, ntohs(spec.rem_port), spec.loc_host,
  			   ntohs(spec.loc_port), rxq_index, flow_id, rc);
  	else
  		netif_info(efx, rx_status, efx->net_dev,
  			   "steering %s [%pI6]:%u:[%pI6]:%u to queue %u [flow %u filter %d]\n",
  			   (spec.ip_proto == IPPROTO_TCP) ? "TCP" : "UDP",
  			   spec.rem_host, ntohs(spec.rem_port), spec.loc_host,
  			   ntohs(spec.loc_port), rxq_index, flow_id, rc);
  
  	return rc;
  }
  
  bool __efx_filter_rfs_expire(struct efx_nic *efx, unsigned int quota)
  {
  	bool (*expire_one)(struct efx_nic *efx, u32 flow_id, unsigned int index);
  	unsigned int channel_idx, index, size;
  	u32 flow_id;
  
  	if (!spin_trylock_bh(&efx->filter_lock))
  		return false;
  
  	expire_one = efx->type->filter_rfs_expire_one;
  	channel_idx = efx->rps_expire_channel;
  	index = efx->rps_expire_index;
  	size = efx->type->max_rx_ip_filters;
  	while (quota--) {
  		struct efx_channel *channel = efx_get_channel(efx, channel_idx);
  		flow_id = channel->rps_flow_id[index];
  
  		if (flow_id != RPS_FLOW_ID_INVALID &&
  		    expire_one(efx, flow_id, index)) {
  			netif_info(efx, rx_status, efx->net_dev,
  				   "expired filter %d [queue %u flow %u]\n",
  				   index, channel_idx, flow_id);
  			channel->rps_flow_id[index] = RPS_FLOW_ID_INVALID;
  		}
  		if (++index == size) {
  			if (++channel_idx == efx->n_channels)
  				channel_idx = 0;
  			index = 0;
  		}
  	}
  	efx->rps_expire_channel = channel_idx;
  	efx->rps_expire_index = index;
  
  	spin_unlock_bh(&efx->filter_lock);
  	return true;
  }
  
  #endif /* CONFIG_RFS_ACCEL */
  
  /**
   * efx_filter_is_mc_recipient - test whether spec is a multicast recipient
   * @spec: Specification to test
   *
   * Return: %true if the specification is a non-drop RX filter that
   * matches a local MAC address I/G bit value of 1 or matches a local
   * IPv4 or IPv6 address value in the respective multicast address
   * range.  Otherwise %false.
   */
  bool efx_filter_is_mc_recipient(const struct efx_filter_spec *spec)
  {
  	if (!(spec->flags & EFX_FILTER_FLAG_RX) ||
  	    spec->dmaq_id == EFX_FILTER_RX_DMAQ_ID_DROP)
  		return false;
  
  	if (spec->match_flags &
  	    (EFX_FILTER_MATCH_LOC_MAC | EFX_FILTER_MATCH_LOC_MAC_IG) &&
  	    is_multicast_ether_addr(spec->loc_mac))
  		return true;
  
  	if ((spec->match_flags &
  	     (EFX_FILTER_MATCH_ETHER_TYPE | EFX_FILTER_MATCH_LOC_HOST)) ==
  	    (EFX_FILTER_MATCH_ETHER_TYPE | EFX_FILTER_MATCH_LOC_HOST)) {
  		if (spec->ether_type == htons(ETH_P_IP) &&
  		    ipv4_is_multicast(spec->loc_host[0]))
  			return true;
  		if (spec->ether_type == htons(ETH_P_IPV6) &&
  		    ((const u8 *)spec->loc_host)[0] == 0xff)
  			return true;
  	}
  
  	return false;
  }
  