bnx2: switch to build_skb() infrastructure

This is very similar to bnx2x conversion, but bnx2 only requires 16bytes
alignement at start of the received frame to store its l2_fhdr, so goal
was not to reduce skb truesize (in fact it should not change after this
patch)

Using build_skb() reduces cache line misses in the driver, since we
use cache hot skb instead of cold ones. Number of in-flight sk_buff
structures is lower, they are more likely recycled in SLUB caches
while still hot.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Michael Chan <mchan@broadcom.com>
CC: Eilon Greenstein <eilong@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/broadcom/bnx2.c b/drivers/net/ethernet/broadcom/bnx2.c
index 6b7cd1e..66f6e7f 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnx2.c
+++ b/drivers/net/ethernet/broadcom/bnx2.c
@@ -2725,31 +2725,27 @@ bnx2_free_rx_page(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, u16 index)
 }
 
 static inline int
-bnx2_alloc_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, u16 index, gfp_t gfp)
+bnx2_alloc_rx_data(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, u16 index, gfp_t gfp)
 {
-       struct sk_buff *skb;
+       u8 *data;
        struct sw_bd *rx_buf = &rxr->rx_buf_ring[index];
        dma_addr_t mapping;
        struct rx_bd *rxbd = &rxr->rx_desc_ring[RX_RING(index)][RX_IDX(index)];
-       unsigned long align;
 
-       skb = __netdev_alloc_skb(bp->dev, bp->rx_buf_size, gfp);
-       if (skb == NULL) {
+       data = kmalloc(bp->rx_buf_size, gfp);
+       if (!data)
                return -ENOMEM;
-       }
 
-       if (unlikely((align = (unsigned long) skb->data & (BNX2_RX_ALIGN - 1))))
-               skb_reserve(skb, BNX2_RX_ALIGN - align);
-
-       mapping = dma_map_single(&bp->pdev->dev, skb->data, bp->rx_buf_use_size,
+       mapping = dma_map_single(&bp->pdev->dev,
+                                get_l2_fhdr(data),
+                                bp->rx_buf_use_size,
                                 PCI_DMA_FROMDEVICE);
        if (dma_mapping_error(&bp->pdev->dev, mapping)) {
-               dev_kfree_skb(skb);
+               kfree(data);
                return -EIO;
        }
 
-       rx_buf->skb = skb;
-       rx_buf->desc = (struct l2_fhdr *) skb->data;
+       rx_buf->data = data;
        dma_unmap_addr_set(rx_buf, mapping, mapping);
 
        rxbd->rx_bd_haddr_hi = (u64) mapping >> 32;
@@ -2956,8 +2952,8 @@ bnx2_reuse_rx_skb_pages(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr,
 }
 
 static inline void
-bnx2_reuse_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr,
-                 struct sk_buff *skb, u16 cons, u16 prod)
+bnx2_reuse_rx_data(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr,
+                  u8 *data, u16 cons, u16 prod)
 {
        struct sw_bd *cons_rx_buf, *prod_rx_buf;
        struct rx_bd *cons_bd, *prod_bd;
@@ -2971,8 +2967,7 @@ bnx2_reuse_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr,
 
        rxr->rx_prod_bseq += bp->rx_buf_use_size;
 
-       prod_rx_buf->skb = skb;
-       prod_rx_buf->desc = (struct l2_fhdr *) skb->data;
+       prod_rx_buf->data = data;
 
        if (cons == prod)
                return;
@@ -2986,33 +2981,39 @@ bnx2_reuse_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr,
        prod_bd->rx_bd_haddr_lo = cons_bd->rx_bd_haddr_lo;
 }
 
-static int
-bnx2_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, struct sk_buff *skb,
+static struct sk_buff *
+bnx2_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, u8 *data,
            unsigned int len, unsigned int hdr_len, dma_addr_t dma_addr,
            u32 ring_idx)
 {
        int err;
        u16 prod = ring_idx & 0xffff;
+       struct sk_buff *skb;
 
-       err = bnx2_alloc_rx_skb(bp, rxr, prod, GFP_ATOMIC);
+       err = bnx2_alloc_rx_data(bp, rxr, prod, GFP_ATOMIC);
        if (unlikely(err)) {
-               bnx2_reuse_rx_skb(bp, rxr, skb, (u16) (ring_idx >> 16), prod);
+               bnx2_reuse_rx_data(bp, rxr, data, (u16) (ring_idx >> 16), prod);
+error:
                if (hdr_len) {
                        unsigned int raw_len = len + 4;
                        int pages = PAGE_ALIGN(raw_len - hdr_len) >> PAGE_SHIFT;
 
                        bnx2_reuse_rx_skb_pages(bp, rxr, NULL, pages);
                }
-               return err;
+               return NULL;
        }
 
-       skb_reserve(skb, BNX2_RX_OFFSET);
        dma_unmap_single(&bp->pdev->dev, dma_addr, bp->rx_buf_use_size,
                         PCI_DMA_FROMDEVICE);
-
+       skb = build_skb(data);
+       if (!skb) {
+               kfree(data);
+               goto error;
+       }
+       skb_reserve(skb, ((u8 *)get_l2_fhdr(data) - data) + BNX2_RX_OFFSET);
        if (hdr_len == 0) {
                skb_put(skb, len);
-               return 0;
+               return skb;
        } else {
                unsigned int i, frag_len, frag_size, pages;
                struct sw_pg *rx_pg;
@@ -3043,7 +3044,7 @@ bnx2_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, struct sk_buff *skb,
                                        skb_frag_size_sub(frag, tail);
                                        skb->data_len -= tail;
                                }
-                               return 0;
+                               return skb;
                        }
                        rx_pg = &rxr->rx_pg_ring[pg_cons];
 
@@ -3065,7 +3066,7 @@ bnx2_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, struct sk_buff *skb,
                                rxr->rx_pg_prod = pg_prod;
                                bnx2_reuse_rx_skb_pages(bp, rxr, skb,
                                                        pages - i);
-                               return err;
+                               return NULL;
                        }
 
                        dma_unmap_page(&bp->pdev->dev, mapping_old,
@@ -3082,7 +3083,7 @@ bnx2_rx_skb(struct bnx2 *bp, struct bnx2_rx_ring_info *rxr, struct sk_buff *skb,
                rxr->rx_pg_prod = pg_prod;
                rxr->rx_pg_cons = pg_cons;
        }
-       return 0;
+       return skb;
 }
 
 static inline u16
@@ -3121,19 +3122,17 @@ bnx2_rx_int(struct bnx2 *bp, struct bnx2_napi *bnapi, int budget)
                struct sw_bd *rx_buf, *next_rx_buf;
                struct sk_buff *skb;
                dma_addr_t dma_addr;
+               u8 *data;
 
                sw_ring_cons = RX_RING_IDX(sw_cons);
                sw_ring_prod = RX_RING_IDX(sw_prod);
 
                rx_buf = &rxr->rx_buf_ring[sw_ring_cons];
-               skb = rx_buf->skb;
-               prefetchw(skb);
+               data = rx_buf->data;
+               rx_buf->data = NULL;
 
-               next_rx_buf =
-                       &rxr->rx_buf_ring[RX_RING_IDX(NEXT_RX_BD(sw_cons))];
-               prefetch(next_rx_buf->desc);
-
-               rx_buf->skb = NULL;
+               rx_hdr = get_l2_fhdr(data);
+               prefetch(rx_hdr);
 
                dma_addr = dma_unmap_addr(rx_buf, mapping);
 
@@ -3141,7 +3140,10 @@ bnx2_rx_int(struct bnx2 *bp, struct bnx2_napi *bnapi, int budget)
                        BNX2_RX_OFFSET + BNX2_RX_COPY_THRESH,
                        PCI_DMA_FROMDEVICE);
 
-               rx_hdr = rx_buf->desc;
+               next_rx_buf =
+                       &rxr->rx_buf_ring[RX_RING_IDX(NEXT_RX_BD(sw_cons))];
+               prefetch(get_l2_fhdr(next_rx_buf->data));
+
                len = rx_hdr->l2_fhdr_pkt_len;
                status = rx_hdr->l2_fhdr_status;
 
@@ -3160,7 +3162,7 @@ bnx2_rx_int(struct bnx2 *bp, struct bnx2_napi *bnapi, int budget)
                                       L2_FHDR_ERRORS_TOO_SHORT |
                                       L2_FHDR_ERRORS_GIANT_FRAME))) {
 
-                       bnx2_reuse_rx_skb(bp, rxr, skb, sw_ring_cons,
+                       bnx2_reuse_rx_data(bp, rxr, data, sw_ring_cons,
                                          sw_ring_prod);
                        if (pg_ring_used) {
                                int pages;
@@ -3175,30 +3177,29 @@ bnx2_rx_int(struct bnx2 *bp, struct bnx2_napi *bnapi, int budget)
                len -= 4;
 
                if (len <= bp->rx_copy_thresh) {
-                       struct sk_buff *new_skb;
-
-                       new_skb = netdev_alloc_skb(bp->dev, len + 6);
-                       if (new_skb == NULL) {
-                               bnx2_reuse_rx_skb(bp, rxr, skb, sw_ring_cons,
+                       skb = netdev_alloc_skb(bp->dev, len + 6);
+                       if (skb == NULL) {
+                               bnx2_reuse_rx_data(bp, rxr, data, sw_ring_cons,
                                                  sw_ring_prod);
                                goto next_rx;
                        }
 
                        /* aligned copy */
-                       skb_copy_from_linear_data_offset(skb,
-                                                        BNX2_RX_OFFSET - 6,
-                                     new_skb->data, len + 6);
-                       skb_reserve(new_skb, 6);
-                       skb_put(new_skb, len);
+                       memcpy(skb->data,
+                              (u8 *)rx_hdr + BNX2_RX_OFFSET - 6,
+                              len + 6);
+                       skb_reserve(skb, 6);
+                       skb_put(skb, len);
 
-                       bnx2_reuse_rx_skb(bp, rxr, skb,
+                       bnx2_reuse_rx_data(bp, rxr, data,
                                sw_ring_cons, sw_ring_prod);
 
-                       skb = new_skb;
-               } else if (unlikely(bnx2_rx_skb(bp, rxr, skb, len, hdr_len,
-                          dma_addr, (sw_ring_cons << 16) | sw_ring_prod)))
-                       goto next_rx;
-
+               } else {
+                       skb = bnx2_rx_skb(bp, rxr, data, len, hdr_len, dma_addr,
+                                         (sw_ring_cons << 16) | sw_ring_prod);
+                       if (!skb)
+                               goto next_rx;
+               }
                if ((status & L2_FHDR_STATUS_L2_VLAN_TAG) &&
                    !(bp->rx_mode & BNX2_EMAC_RX_MODE_KEEP_VLAN_TAG))
                        __vlan_hwaccel_put_tag(skb, rx_hdr->l2_fhdr_vlan_tag);
@@ -5225,7 +5226,7 @@ bnx2_init_rx_ring(struct bnx2 *bp, int ring_num)
 
        ring_prod = prod = rxr->rx_prod;
        for (i = 0; i < bp->rx_ring_size; i++) {
-               if (bnx2_alloc_rx_skb(bp, rxr, ring_prod, GFP_KERNEL) < 0) {
+               if (bnx2_alloc_rx_data(bp, rxr, ring_prod, GFP_KERNEL) < 0) {
                        netdev_warn(bp->dev, "init'ed rx ring %d with %d/%d skbs only\n",
                                    ring_num, i, bp->rx_ring_size);
                        break;
@@ -5320,7 +5321,7 @@ bnx2_set_rx_ring_size(struct bnx2 *bp, u32 size)
        rx_size = bp->dev->mtu + ETH_HLEN + BNX2_RX_OFFSET + 8;
 
        rx_space = SKB_DATA_ALIGN(rx_size + BNX2_RX_ALIGN) + NET_SKB_PAD +
-               sizeof(struct skb_shared_info);
+               SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
        bp->rx_copy_thresh = BNX2_RX_COPY_THRESH;
        bp->rx_pg_ring_size = 0;
@@ -5342,8 +5343,9 @@ bnx2_set_rx_ring_size(struct bnx2 *bp, u32 size)
        }
 
        bp->rx_buf_use_size = rx_size;
-       /* hw alignment */
-       bp->rx_buf_size = bp->rx_buf_use_size + BNX2_RX_ALIGN;
+       /* hw alignment + build_skb() overhead*/
+       bp->rx_buf_size = SKB_DATA_ALIGN(bp->rx_buf_use_size + BNX2_RX_ALIGN) +
+               NET_SKB_PAD + SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
        bp->rx_jumbo_thresh = rx_size - BNX2_RX_OFFSET;
        bp->rx_ring_size = size;
        bp->rx_max_ring = bnx2_find_max_ring(size, MAX_RX_RINGS);
@@ -5409,9 +5411,9 @@ bnx2_free_rx_skbs(struct bnx2 *bp)
 
                for (j = 0; j < bp->rx_max_ring_idx; j++) {
                        struct sw_bd *rx_buf = &rxr->rx_buf_ring[j];
-                       struct sk_buff *skb = rx_buf->skb;
+                       u8 *data = rx_buf->data;
 
-                       if (skb == NULL)
+                       if (data == NULL)
                                continue;
 
                        dma_unmap_single(&bp->pdev->dev,
@@ -5419,9 +5421,9 @@ bnx2_free_rx_skbs(struct bnx2 *bp)
                                         bp->rx_buf_use_size,
                                         PCI_DMA_FROMDEVICE);
 
-                       rx_buf->skb = NULL;
+                       rx_buf->data = NULL;
 
-                       dev_kfree_skb(skb);
+                       kfree(data);
                }
                for (j = 0; j < bp->rx_max_pg_ring_idx; j++)
                        bnx2_free_rx_page(bp, rxr, j);
@@ -5727,7 +5729,8 @@ static int
 bnx2_run_loopback(struct bnx2 *bp, int loopback_mode)
 {
        unsigned int pkt_size, num_pkts, i;
-       struct sk_buff *skb, *rx_skb;
+       struct sk_buff *skb;
+       u8 *data;
        unsigned char *packet;
        u16 rx_start_idx, rx_idx;
        dma_addr_t map;
@@ -5819,14 +5822,14 @@ bnx2_run_loopback(struct bnx2 *bp, int loopback_mode)
        }
 
        rx_buf = &rxr->rx_buf_ring[rx_start_idx];
-       rx_skb = rx_buf->skb;
+       data = rx_buf->data;
 
-       rx_hdr = rx_buf->desc;
-       skb_reserve(rx_skb, BNX2_RX_OFFSET);
+       rx_hdr = get_l2_fhdr(data);
+       data = (u8 *)rx_hdr + BNX2_RX_OFFSET;
 
        dma_sync_single_for_cpu(&bp->pdev->dev,
                dma_unmap_addr(rx_buf, mapping),
-               bp->rx_buf_size, PCI_DMA_FROMDEVICE);
+               bp->rx_buf_use_size, PCI_DMA_FROMDEVICE);
 
        if (rx_hdr->l2_fhdr_status &
                (L2_FHDR_ERRORS_BAD_CRC |
@@ -5843,7 +5846,7 @@ bnx2_run_loopback(struct bnx2 *bp, int loopback_mode)
        }
 
        for (i = 14; i < pkt_size; i++) {
-               if (*(rx_skb->data + i) != (unsigned char) (i & 0xff)) {
+               if (*(data + i) != (unsigned char) (i & 0xff)) {
                        goto loopback_test_done;
                }
        }

diff --git a/drivers/net/ethernet/broadcom/bnx2.h b/drivers/net/ethernet/broadcom/bnx2.h
index 99d31a7..1db2d51 100644 (file)
--- a/drivers/net/ethernet/broadcom/bnx2.h
+++ b/drivers/net/ethernet/broadcom/bnx2.h
@@ -6563,12 +6563,25 @@ struct l2_fhdr {
 #define MB_TX_CID_ADDR MB_GET_CID_ADDR(TX_CID)
 #define MB_RX_CID_ADDR MB_GET_CID_ADDR(RX_CID)
 
+/*
+ * This driver uses new build_skb() API :
+ * RX ring buffer contains pointer to kmalloc() data only,
+ * skb are built only after Hardware filled the frame.
+ */
 struct sw_bd {
-       struct sk_buff          *skb;
-       struct l2_fhdr          *desc;
+       u8                      *data;
        DEFINE_DMA_UNMAP_ADDR(mapping);
 };
 
+/* Its faster to compute this from data than storing it in sw_bd
+ * (less cache misses)
+ */
+static inline struct l2_fhdr *get_l2_fhdr(u8 *data)
+{
+       return (struct l2_fhdr *)(PTR_ALIGN(data, BNX2_RX_ALIGN) + NET_SKB_PAD);
+}
+
+
 struct sw_pg {
        struct page             *page;
        DEFINE_DMA_UNMAP_ADDR(mapping);