Messages in this thread | | | Date | Tue, 13 Aug 2019 14:11:23 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH net-next v2 02/12] net: stmmac: Prepare to add Split Header support |
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On Mon, 12 Aug 2019 11:44:01 +0200, Jose Abreu wrote: > In order to add Split Header support, stmmac_rx() needs to take into > account that packet may be split accross multiple descriptors. > > Refactor the logic of this function in order to support this scenario. > > Signed-off-by: Jose Abreu <joabreu@synopsys.com> > > --- > Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com> > Cc: Alexandre Torgue <alexandre.torgue@st.com> > Cc: Jose Abreu <joabreu@synopsys.com> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> > Cc: netdev@vger.kernel.org > Cc: linux-stm32@st-md-mailman.stormreply.com > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > --- > drivers/net/ethernet/stmicro/stmmac/stmmac.h | 6 + > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 149 +++++++++++++--------- > 2 files changed, 95 insertions(+), 60 deletions(-) > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h > index 80276587048a..56158e1448ac 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h > @@ -74,6 +74,12 @@ struct stmmac_rx_queue { > u32 rx_zeroc_thresh; > dma_addr_t dma_rx_phy; > u32 rx_tail_addr; > + unsigned int state_saved; > + struct { > + struct sk_buff *skb; > + unsigned int len; > + unsigned int error; > + } state; > }; > > struct stmmac_channel { > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > index b2e5f4ecd551..a093eb4ec275 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -3353,9 +3353,10 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > { > struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue]; > struct stmmac_channel *ch = &priv->channel[queue]; > + unsigned int count = 0, error = 0, len = 0; > + int status = 0, coe = priv->hw->rx_csum; > unsigned int next_entry = rx_q->cur_rx; > - int coe = priv->hw->rx_csum; > - unsigned int count = 0; > + struct sk_buff *skb = NULL; > > if (netif_msg_rx_status(priv)) { > void *rx_head; > @@ -3369,9 +3370,27 @@ 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) { > + enum pkt_hash_types hash_type; > struct stmmac_rx_buffer *buf; > + unsigned int prev_len = 0; > struct dma_desc *np, *p; > - int entry, status; > + int entry; > + u32 hash; > + > + if (!count && rx_q->state_saved) { > + skb = rx_q->state.skb; > + error = rx_q->state.error; > + len = rx_q->state.len; > + } else { > + rx_q->state_saved = false; > + skb = NULL; > + error = 0; > + len = 0; > + } > + > +read_again: > + if (count >= limit) > + break;
Is this stopping the NAPI poll once @limit descriptors were seen? It should probably be okay to ignore the limit until you get a full frame? I'd think it'd be best to finish up the frame while the state is hot in the CPU cache.. WDYT?
> entry = next_entry; > buf = &rx_q->buf_pool[entry]; > @@ -3407,28 +3426,24 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > page_pool_recycle_direct(rx_q->page_pool, buf->page); > priv->dev->stats.rx_errors++; > buf->page = NULL; > + error = 1; > + } > + > + if (unlikely(error & (status & rx_not_ls)))
Looks suspicious - sure this is supposed to be error & (status & bla) and not error && ... ?
> + goto read_again; > + if (unlikely(error)) { > + if (skb) > + dev_kfree_skb(skb); > + continue; > + } > + > + /* Buffer is good. Go on. */ > + > + if (likely(status & rx_not_ls)) { > + len += priv->dma_buf_sz; > } else { > - enum pkt_hash_types hash_type; > - struct sk_buff *skb; > - unsigned int des; > - int frame_len; > - u32 hash; > - > - stmmac_get_desc_addr(priv, p, &des); > - frame_len = stmmac_get_rx_frame_len(priv, p, coe); > - > - /* If frame length is greater than skb buffer size > - * (preallocated during init) then the packet is > - * ignored > - */ > - if (frame_len > priv->dma_buf_sz) { > - if (net_ratelimit()) > - netdev_err(priv->dev, > - "len %d larger than size (%d)\n", > - frame_len, priv->dma_buf_sz); > - priv->dev->stats.rx_length_errors++; > - continue; > - } > + 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) > @@ -3439,57 +3454,71 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > */ > if (unlikely(priv->synopsys_id >= DWMAC_CORE_4_00) || > unlikely(status != llc_snap)) > - frame_len -= ETH_FCS_LEN; > - > - if (netif_msg_rx_status(priv)) { > - netdev_dbg(priv->dev, "\tdesc: %p [entry %d] buff=0x%x\n", > - p, entry, des); > - netdev_dbg(priv->dev, "frame size %d, COE: %d\n", > - frame_len, status); > - } > + len -= ETH_FCS_LEN; > + } > > - skb = netdev_alloc_skb_ip_align(priv->dev, frame_len); > - if (unlikely(!skb)) { > + if (!skb) { > + skb = netdev_alloc_skb_ip_align(priv->dev, len);
Since you're in NAPI call perhaps something like napi_alloc_skb() could speed things up a little? But please also see below..
> + if (!skb) { > priv->dev->stats.rx_dropped++; > continue; > } > > - dma_sync_single_for_cpu(priv->device, buf->addr, > - frame_len, DMA_FROM_DEVICE); > + dma_sync_single_for_cpu(priv->device, buf->addr, len, > + DMA_FROM_DEVICE); > skb_copy_to_linear_data(skb, page_address(buf->page), > - frame_len); > - skb_put(skb, frame_len); > + len); > + skb_put(skb, len); > > - if (netif_msg_pktdata(priv)) { > - netdev_dbg(priv->dev, "frame received (%dbytes)", > - frame_len); > - print_pkt(skb->data, frame_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; > > - stmmac_get_rx_hwtstamp(priv, p, np, skb); > + if (likely(status & rx_not_ls)) > + buf_len = priv->dma_buf_sz; > > - stmmac_rx_vlan(priv->dev, skb); > + dma_sync_single_for_cpu(priv->device, buf->addr, > + buf_len, DMA_FROM_DEVICE); > + skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, > + buf->page, 0, buf_len, > + priv->dma_buf_sz); > > - skb->protocol = eth_type_trans(skb, priv->dev); > + /* Data payload appended into SKB */ > + page_pool_release_page(rx_q->page_pool, buf->page); > + buf->page = NULL; > + } > > - if (unlikely(!coe)) > - skb_checksum_none_assert(skb); > - else > - skb->ip_summed = CHECKSUM_UNNECESSARY; > + if (likely(status & rx_not_ls)) > + goto read_again; > > - if (!stmmac_get_rx_hash(priv, p, &hash, &hash_type)) > - skb_set_hash(skb, hash, hash_type); > + /* Got entire packet into SKB. Finish it. */ > > - skb_record_rx_queue(skb, queue); > - napi_gro_receive(&ch->rx_napi, skb); > + stmmac_get_rx_hwtstamp(priv, p, np, skb); > + stmmac_rx_vlan(priv->dev, skb); > + skb->protocol = eth_type_trans(skb, priv->dev); > > - /* Data payload copied into SKB, page ready for recycle */ > - page_pool_recycle_direct(rx_q->page_pool, buf->page); > - buf->page = NULL; > + if (unlikely(!coe)) > + skb_checksum_none_assert(skb); > + else > + skb->ip_summed = CHECKSUM_UNNECESSARY; > > - priv->dev->stats.rx_packets++; > - priv->dev->stats.rx_bytes += frame_len; > - } > + if (!stmmac_get_rx_hash(priv, p, &hash, &hash_type)) > + skb_set_hash(skb, hash, hash_type); > + > + skb_record_rx_queue(skb, queue); > + napi_gro_receive(&ch->rx_napi, skb);
Did you look into using napi_gro_frags() family of APIs? I think Eric said those are more efficient from GRO perspective..
> + priv->dev->stats.rx_packets++; > + priv->dev->stats.rx_bytes += len; > + } > + > + if (status & rx_not_ls) { > + rx_q->state_saved = true; > + rx_q->state.skb = skb; > + rx_q->state.error = error; > + rx_q->state.len = len; > } > > stmmac_rx_refill(priv, queue);
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