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r8169: improve rx buffer allocation 

8 years ago, as part of 6f0333b8fd ("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: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Heiner Kallweit 2019-01-20 11:12:01 +01:00 committed by David S. Miller
parent a5996989d5
commit 6dc8b74bf5
1 changed files with 5 additions and 13 deletions
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18
drivers/net/ethernet/realtek/r8169.c
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@ -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);