[PATCH 01/10] net: add and use SKB_ALLOCSIZE

Ian Campbell
2012-04-10T14:32:40Z

This gives the allocation size required for an skb containing X bytes of data

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
drivers/net/ethernet/broadcom/bnx2.c | 7 +++----
drivers/net/ethernet/broadcom/bnx2x/bnx2x.h | 3 +--
drivers/net/ethernet/broadcom/tg3.c | 3 +--
include/linux/skbuff.h | 12 ++++++++++++
net/core/skbuff.c | 8 +-------
5 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2.c b/drivers/net/ethernet/broadcom/bnx2.c
index 8297e28..dede71f 100644
--- a/drivers/net/ethernet/broadcom/bnx2.c
+++ b/drivers/net/ethernet/broadcom/bnx2.c
@@ -5321,8 +5321,7 @@ bnx2_set_rx_ring_size(struct bnx2 *bp, u32 size)
/* 8 for CRC and VLAN */
rx_size = bp->dev->mtu + ETH_HLEN + BNX2_RX_OFFSET + 8;

- rx_space = SKB_DATA_ALIGN(rx_size + BNX2_RX_ALIGN) + NET_SKB_PAD +
- SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+ rx_space = SKB_ALLOCSIZE(rx_size + BNX2_RX_ALIGN) + NET_SKB_PAD;

bp->rx_copy_thresh = BNX2_RX_COPY_THRESH;
bp->rx_pg_ring_size = 0;
@@ -5345,8 +5344,8 @@ bnx2_set_rx_ring_size(struct bnx2 *bp, u32 size)

bp->rx_buf_use_size = rx_size;
/* 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_buf_size = SKB_ALLOCSIZE(bp->rx_buf_use_size + BNX2_RX_ALIGN) +
+ NET_SKB_PAD;
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);
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
index e37161f..12f2ceb 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x.h
@@ -1229,8 +1229,7 @@ struct bnx2x {
#define BNX2X_FW_RX_ALIGN_START (1UL << BNX2X_RX_ALIGN_SHIFT)

#define BNX2X_FW_RX_ALIGN_END \
- max(1UL << BNX2X_RX_ALIGN_SHIFT, \
- SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
+ max(1UL << BNX2X_RX_ALIGN_SHIFT, SKB_ALLOCSIZE(0))

#define BNX2X_PXP_DRAM_ALIGN (BNX2X_RX_ALIGN_SHIFT - 5)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 7b71387..4d4b063 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -5672,8 +5672,7 @@ static int tg3_alloc_rx_data(struct tg3 *tp, struct tg3_rx_prodring_set *tpr,
* Callers depend upon this behavior and assume that
* we leave everything unchanged if we fail.
*/
- skb_size = SKB_DATA_ALIGN(data_size + TG3_RX_OFFSET(tp)) +
- SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+ skb_size = SKB_ALLOCSIZE(data_size + TG3_RX_OFFSET(tp));
data = kmalloc(skb_size, GFP_ATOMIC);
if (!data)
return -ENOMEM;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 192250b..fbc92b2 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -41,8 +41,20 @@

#define SKB_DATA_ALIGN(X) (((X) + (SMP_CACHE_BYTES - 1)) & \
~(SMP_CACHE_BYTES - 1))
+/* maximum data size which can fit into an allocation of X bytes */
#define SKB_WITH_OVERHEAD(X) \
((X) - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
+/*
+ * minimum allocation size required for an skb containing X bytes of data
+ *
+ * We do our best to align skb_shared_info on a separate cache
+ * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
+ * aligned memory blocks, unless SLUB/SLAB debug is enabled. Both
+ * skb->head and skb_shared_info are cache line aligned.
+ */
+#define SKB_ALLOCSIZE(X) \
+ (SKB_DATA_ALIGN((X)) + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
+
#define SKB_MAX_ORDER(X, ORDER) \
SKB_WITH_OVERHEAD((PAGE_SIZE << (ORDER)) - (X))
#define SKB_MAX_HEAD(X) (SKB_MAX_ORDER((X), 0))
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a690cae..59a1ecb 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -184,13 +184,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
goto out;
prefetchw(skb);

- /* We do our best to align skb_shared_info on a separate cache
- * line. It usually works because kmalloc(X > SMP_CACHE_BYTES) gives
- * aligned memory blocks, unless SLUB/SLAB debug is enabled.
- * Both skb->head and skb_shared_info are cache line aligned.
- */
- size = SKB_DATA_ALIGN(size);
- size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+ size = SKB_ALLOCSIZE(size);
data = kmalloc_node_track_caller(size, gfp_mask, node);
if (!data)
goto nodata;
--
1.7.2.5