sfc: Reduce size of efx_rx_buffer further by removing data member

Instead calculate the KVA of receive data. It's not like it's a hard sum.

[bwh: Fixed to work with GRO.]
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

2 files changed, 28 insertions, 24 deletions

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index 59ff32ac7ec6..5b001c1c73d4 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -214,7 +214,6 @@ struct efx_tx_queue {
  *      If both this and page are %NULL, the buffer slot is currently free.
  * @page: The associated page buffer, if any.
  *      If both this and skb are %NULL, the buffer slot is currently free.
- * @data: Pointer to ethernet header
  * @len: Buffer length, in bytes.
  * @is_page: Indicates if @page is valid. If false, @skb is valid.
  */
@@ -224,7 +223,6 @@ struct efx_rx_buffer {
                 struct sk_buff *skb;
                 struct page *page;
         } u;
-        char *data;
         unsigned int len;
         bool is_page;
 };
diff --git a/drivers/net/sfc/rx.c b/drivers/net/sfc/rx.c
index bcbd2ec2d92a..81bec873e9d3 100644
--- a/drivers/net/sfc/rx.c
+++ b/drivers/net/sfc/rx.c
@@ -89,24 +89,37 @@ static unsigned int rx_refill_limit = 95;
  */
 #define EFX_RXD_HEAD_ROOM 2
 
-static inline unsigned int efx_rx_buf_offset(struct efx_rx_buffer *buf)
+/* Offset of ethernet header within page */
+static inline unsigned int efx_rx_buf_offset(struct efx_nic *efx,
+                                             struct efx_rx_buffer *buf)
 {
         /* Offset is always within one page, so we don't need to consider
          * the page order.
          */
-        return (__force unsigned long) buf->data & (PAGE_SIZE - 1);
+        return (((__force unsigned long) buf->dma_addr & (PAGE_SIZE - 1)) +
+                efx->type->rx_buffer_hash_size);
 }
 static inline unsigned int efx_rx_buf_size(struct efx_nic *efx)
 {
         return PAGE_SIZE << efx->rx_buffer_order;
 }
 
-static inline u32 efx_rx_buf_hash(struct efx_rx_buffer *buf)
+static u8 *efx_rx_buf_eh(struct efx_nic *efx, struct efx_rx_buffer *buf)
 {
+        if (buf->is_page)
+                return page_address(buf->u.page) + efx_rx_buf_offset(efx, buf);
+        else
+                return ((u8 *)buf->u.skb->data +
+                        efx->type->rx_buffer_hash_size);
+}
+
+static inline u32 efx_rx_buf_hash(const u8 *eh)
+{
+        /* The ethernet header is always directly after any hash. */
 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) || NET_IP_ALIGN % 4 == 0
-        return __le32_to_cpup((const __le32 *)(buf->data - 4));
+        return __le32_to_cpup((const __le32 *)(eh - 4));
 #else
-        const u8 *data = (const u8 *)(buf->data - 4);
+        const u8 *data = eh - 4;
         return ((u32)data[0]       |
                 (u32)data[1] << 8  |
                 (u32)data[2] << 16 |
@@ -143,13 +156,12 @@ static int efx_init_rx_buffers_skb(struct efx_rx_queue *rx_queue)
 
                 /* Adjust the SKB for padding and checksum */
                 skb_reserve(skb, NET_IP_ALIGN);
-                rx_buf->data = (char *)skb->data;
                 rx_buf->len = skb_len - NET_IP_ALIGN;
                 rx_buf->is_page = false;
                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 
                 rx_buf->dma_addr = pci_map_single(efx->pci_dev,
-                                                  rx_buf->data, rx_buf->len,
+                                                  skb->data, rx_buf->len,
                                                   PCI_DMA_FROMDEVICE);
                 if (unlikely(pci_dma_mapping_error(efx->pci_dev,
                                                    rx_buf->dma_addr))) {
@@ -213,7 +225,6 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue)
                 rx_buf = efx_rx_buffer(rx_queue, index);
                 rx_buf->dma_addr = dma_addr + EFX_PAGE_IP_ALIGN;
                 rx_buf->u.page = page;
-                rx_buf->data = page_addr + EFX_PAGE_IP_ALIGN;
                 rx_buf->len = efx->rx_buffer_len - EFX_PAGE_IP_ALIGN;
                 rx_buf->is_page = true;
                 ++rx_queue->added_count;
@@ -297,8 +308,6 @@ static void efx_resurrect_rx_buffer(struct efx_rx_queue *rx_queue,
         new_buf = efx_rx_buffer(rx_queue, index);
         new_buf->dma_addr = rx_buf->dma_addr ^ (PAGE_SIZE >> 1);
         new_buf->u.page = rx_buf->u.page;
-        new_buf->data = (void *)
-                ((__force unsigned long)rx_buf->data ^ (PAGE_SIZE >> 1));
         new_buf->len = rx_buf->len;
         new_buf->is_page = true;
         ++rx_queue->added_count;
@@ -446,7 +455,7 @@ static void efx_rx_packet__check_len(struct efx_rx_queue *rx_queue,
  */
 static void efx_rx_packet_gro(struct efx_channel *channel,
                               struct efx_rx_buffer *rx_buf,
-                              bool checksummed)
+                              const u8 *eh, bool checksummed)
 {
         struct napi_struct *napi = &channel->napi_str;
         gro_result_t gro_result;
@@ -466,11 +475,11 @@ static void efx_rx_packet_gro(struct efx_channel *channel,
                 }
 
                 if (efx->net_dev->features & NETIF_F_RXHASH)
-                        skb->rxhash = efx_rx_buf_hash(rx_buf);
+                        skb->rxhash = efx_rx_buf_hash(eh);
 
                 skb_shinfo(skb)->frags[0].page = page;
                 skb_shinfo(skb)->frags[0].page_offset =
-                        efx_rx_buf_offset(rx_buf);
+                        efx_rx_buf_offset(efx, rx_buf);
                 skb_shinfo(skb)->frags[0].size = rx_buf->len;
                 skb_shinfo(skb)->nr_frags = 1;
 
@@ -509,7 +518,6 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
         bool leak_packet = false;
 
         rx_buf = efx_rx_buffer(rx_queue, index);
-        EFX_BUG_ON_PARANOID(!rx_buf->data);
 
         /* This allows the refill path to post another buffer.
          * EFX_RXD_HEAD_ROOM ensures that the slot we are using
@@ -548,12 +556,12 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
         /* Prefetch nice and early so data will (hopefully) be in cache by
          * the time we look at it.
          */
-        prefetch(rx_buf->data);
+        prefetch(efx_rx_buf_eh(efx, rx_buf));
 
         /* Pipeline receives so that we give time for packet headers to be
          * prefetched into cache.
          */
-        rx_buf->len = len;
+        rx_buf->len = len - efx->type->rx_buffer_hash_size;
 out:
         if (channel->rx_pkt)
                 __efx_rx_packet(channel,
@@ -568,15 +576,13 @@ void __efx_rx_packet(struct efx_channel *channel,
 {
         struct efx_nic *efx = channel->efx;
         struct sk_buff *skb;
-
-        rx_buf->data += efx->type->rx_buffer_hash_size;
-        rx_buf->len -= efx->type->rx_buffer_hash_size;
+        u8 *eh = efx_rx_buf_eh(efx, rx_buf);
 
         /* 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)) {
-                efx_loopback_rx_packet(efx, rx_buf->data, rx_buf->len);
+                efx_loopback_rx_packet(efx, eh, rx_buf->len);
                 efx_free_rx_buffer(efx, rx_buf);
                 return;
         }
@@ -590,7 +596,7 @@ void __efx_rx_packet(struct efx_channel *channel,
                 skb_put(skb, rx_buf->len);
 
                 if (efx->net_dev->features & NETIF_F_RXHASH)
-                        skb->rxhash = efx_rx_buf_hash(rx_buf);
+                        skb->rxhash = efx_rx_buf_hash(eh);
 
                 /* Move past the ethernet header. rx_buf->data still points
                  * at the ethernet header */
@@ -600,7 +606,7 @@ void __efx_rx_packet(struct efx_channel *channel,
         }
 
         if (likely(checksummed || rx_buf->is_page)) {
-                efx_rx_packet_gro(channel, rx_buf, checksummed);
+                efx_rx_packet_gro(channel, rx_buf, eh, checksummed);
                 return;
         }