Commit 6dc8b74b authored by Heiner Kallweit's avatar Heiner Kallweit Committed by David S. Miller
Browse files

r8169: improve rx buffer allocation 



8 years ago, as part of 6f0333b8 ("r8169: use 50% less ram for RX
ring"), the alignment requirement for rx buffers was silently changed
from 8 bytes to 16 bytes. I found nothing explaining this, also the
chip specs I have only mention an 8 byte requirement.
AFAICS kmalloc_node() guarantees allocated memory to be at least
"long long" aligned, what is 8 bytes on a 32 bit machine.
So we can take this memory as-is and avoid some overhead by changing
the alignment requirement back to 8 bytes.

Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a5996989

drivers/net/ethernet/realtek/r8169.c

+5 −13
Original line number Diff line number Diff line
@@ -5659,11 +5659,6 @@ static inline void rtl8169_mark_to_asic(struct RxDesc *desc) 
	desc->opts1 = cpu_to_le32(DescOwn | eor | R8169_RX_BUF_SIZE);

}



static inline void *rtl8169_align(void *data)

{

	return (void *)ALIGN((long)data, 16);

}



static struct sk_buff *rtl8169_alloc_rx_data(struct rtl8169_private *tp,

					     struct RxDesc *desc)

{
@@ -5676,15 +5671,13 @@ static struct sk_buff *rtl8169_alloc_rx_data(struct rtl8169_private *tp, 
	if (!data)

		return NULL;



	if (rtl8169_align(data) != data) {

		kfree(data);

		data = kmalloc_node(R8169_RX_BUF_SIZE + 15, GFP_KERNEL, node);

		if (!data)

			return NULL;

	/* Memory should be properly aligned, but better check. */

	if (!IS_ALIGNED((unsigned long)data, 8)) {

		netdev_err_once(tp->dev, "RX buffer not 8-byte-aligned\n");

		goto err_out;

	}



	mapping = dma_map_single(d, rtl8169_align(data), R8169_RX_BUF_SIZE,

				 DMA_FROM_DEVICE);

	mapping = dma_map_single(d, data, R8169_RX_BUF_SIZE, DMA_FROM_DEVICE);

	if (unlikely(dma_mapping_error(d, mapping))) {

		if (net_ratelimit())

			netif_err(tp, drv, tp->dev, "Failed to map RX DMA!\n");
@@ -6290,7 +6283,6 @@ static struct sk_buff *rtl8169_try_rx_copy(void *data, 
	struct sk_buff *skb;

	struct device *d = tp_to_dev(tp);



	data = rtl8169_align(data);

	dma_sync_single_for_cpu(d, addr, pkt_size, DMA_FROM_DEVICE);

	prefetch(data);

	skb = napi_alloc_skb(&tp->napi, pkt_size);

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