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net: stmmac: Rework stmmac_rx()
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This looks over-engineered. Let's use some helpers to get the buffer
length and hereby simplify the stmmac_rx() function. No performance drop
was seen with the new implementation.

Signed-off-by: Jose Abreu <Jose.Abreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Jose Abreu authored and David S. Miller committed Nov 12, 2019
1 parent bc41a66 commit 88ebe2c
Showing 1 changed file with 94 additions and 52 deletions.
146 changes: 94 additions & 52 deletions drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3443,6 +3443,55 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
stmmac_set_rx_tail_ptr(priv, priv->ioaddr, rx_q->rx_tail_addr, queue);
}

static unsigned int stmmac_rx_buf1_len(struct stmmac_priv *priv,
struct dma_desc *p,
int status, unsigned int len)
{
int ret, coe = priv->hw->rx_csum;
unsigned int plen = 0, hlen = 0;

/* Not first descriptor, buffer is always zero */
if (priv->sph && len)
return 0;

/* First descriptor, get split header length */
ret = stmmac_get_rx_header_len(priv, p, &hlen);
if (priv->sph && hlen) {
priv->xstats.rx_split_hdr_pkt_n++;
return hlen;
}

/* First descriptor, not last descriptor and not split header */
if (status & rx_not_ls)
return priv->dma_buf_sz;

plen = stmmac_get_rx_frame_len(priv, p, coe);

/* First descriptor and last descriptor and not split header */
return min_t(unsigned int, priv->dma_buf_sz, plen);
}

static unsigned int stmmac_rx_buf2_len(struct stmmac_priv *priv,
struct dma_desc *p,
int status, unsigned int len)
{
int coe = priv->hw->rx_csum;
unsigned int plen = 0;

/* Not split header, buffer is not available */
if (!priv->sph)
return 0;

/* Not last descriptor */
if (status & rx_not_ls)
return priv->dma_buf_sz;

plen = stmmac_get_rx_frame_len(priv, p, coe);

/* Last descriptor */
return plen - len;
}

/**
* stmmac_rx - manage the receive process
* @priv: driver private structure
Expand Down Expand Up @@ -3472,11 +3521,10 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
stmmac_display_ring(priv, rx_head, DMA_RX_SIZE, true);
}
while (count < limit) {
unsigned int hlen = 0, prev_len = 0;
unsigned int buf1_len = 0, buf2_len = 0;
enum pkt_hash_types hash_type;
struct stmmac_rx_buffer *buf;
struct dma_desc *np, *p;
unsigned int sec_len;
int entry;
u32 hash;

Expand All @@ -3495,7 +3543,8 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
break;

read_again:
sec_len = 0;
buf1_len = 0;
buf2_len = 0;
entry = next_entry;
buf = &rx_q->buf_pool[entry];

Expand All @@ -3520,7 +3569,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
np = rx_q->dma_rx + next_entry;

prefetch(np);
prefetch(page_address(buf->page));

if (priv->extend_desc)
stmmac_rx_extended_status(priv, &priv->dev->stats,
Expand All @@ -3537,92 +3585,85 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
goto read_again;
if (unlikely(error)) {
dev_kfree_skb(skb);
skb = NULL;
count++;
continue;
}

/* Buffer is good. Go on. */

if (likely(status & rx_not_ls)) {
len += priv->dma_buf_sz;
} else {
prev_len = len;
len = stmmac_get_rx_frame_len(priv, p, coe);

/* ACS is set; GMAC core strips PAD/FCS for IEEE 802.3
* Type frames (LLC/LLC-SNAP)
*
* llc_snap is never checked in GMAC >= 4, so this ACS
* feature is always disabled and packets need to be
* stripped manually.
*/
if (unlikely(priv->synopsys_id >= DWMAC_CORE_4_00) ||
unlikely(status != llc_snap))
len -= ETH_FCS_LEN;
prefetch(page_address(buf->page));
if (buf->sec_page)
prefetch(page_address(buf->sec_page));

buf1_len = stmmac_rx_buf1_len(priv, p, status, len);
len += buf1_len;
buf2_len = stmmac_rx_buf2_len(priv, p, status, len);
len += buf2_len;

/* ACS is set; GMAC core strips PAD/FCS for IEEE 802.3
* Type frames (LLC/LLC-SNAP)
*
* llc_snap is never checked in GMAC >= 4, so this ACS
* feature is always disabled and packets need to be
* stripped manually.
*/
if (unlikely(priv->synopsys_id >= DWMAC_CORE_4_00) ||
unlikely(status != llc_snap)) {
if (buf2_len)
buf2_len -= ETH_FCS_LEN;
else
buf1_len -= ETH_FCS_LEN;

len -= ETH_FCS_LEN;
}

if (!skb) {
int ret = stmmac_get_rx_header_len(priv, p, &hlen);

if (priv->sph && !ret && (hlen > 0)) {
sec_len = len;
if (!(status & rx_not_ls))
sec_len = sec_len - hlen;
len = hlen;

prefetch(page_address(buf->sec_page));
priv->xstats.rx_split_hdr_pkt_n++;
}

skb = napi_alloc_skb(&ch->rx_napi, len);
skb = napi_alloc_skb(&ch->rx_napi, buf1_len);
if (!skb) {
priv->dev->stats.rx_dropped++;
count++;
continue;
goto drain_data;
}

dma_sync_single_for_cpu(priv->device, buf->addr, len,
DMA_FROM_DEVICE);
dma_sync_single_for_cpu(priv->device, buf->addr,
buf1_len, DMA_FROM_DEVICE);
skb_copy_to_linear_data(skb, page_address(buf->page),
len);
skb_put(skb, len);
buf1_len);
skb_put(skb, buf1_len);

/* Data payload copied into SKB, page ready for recycle */
page_pool_recycle_direct(rx_q->page_pool, buf->page);
buf->page = NULL;
} else {
unsigned int buf_len = len - prev_len;

if (likely(status & rx_not_ls))
buf_len = priv->dma_buf_sz;

} else if (buf1_len) {
dma_sync_single_for_cpu(priv->device, buf->addr,
buf_len, DMA_FROM_DEVICE);
buf1_len, DMA_FROM_DEVICE);
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
buf->page, 0, buf_len,
buf->page, 0, buf1_len,
priv->dma_buf_sz);

/* Data payload appended into SKB */
page_pool_release_page(rx_q->page_pool, buf->page);
buf->page = NULL;
}

if (sec_len > 0) {
if (buf2_len) {
dma_sync_single_for_cpu(priv->device, buf->sec_addr,
sec_len, DMA_FROM_DEVICE);
buf2_len, DMA_FROM_DEVICE);
skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
buf->sec_page, 0, sec_len,
buf->sec_page, 0, buf2_len,
priv->dma_buf_sz);

len += sec_len;

/* Data payload appended into SKB */
page_pool_release_page(rx_q->page_pool, buf->sec_page);
buf->sec_page = NULL;
}

drain_data:
if (likely(status & rx_not_ls))
goto read_again;
if (!skb)
continue;

/* Got entire packet into SKB. Finish it. */

Expand All @@ -3640,13 +3681,14 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)

skb_record_rx_queue(skb, queue);
napi_gro_receive(&ch->rx_napi, skb);
skb = NULL;

priv->dev->stats.rx_packets++;
priv->dev->stats.rx_bytes += len;
count++;
}

if (status & rx_not_ls) {
if (status & rx_not_ls || skb) {
rx_q->state_saved = true;
rx_q->state.skb = skb;
rx_q->state.error = error;
Expand Down

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