[PATCHv4 net-next 1/8] net: ibm: emac: use netif_receive_skb_list

[Rosen Penev]

Small rx improvement. Would use napi_gro_receive instead but that's a
lot more involved than netif_receive_skb_list because of how the
function is implemented.

Before:

> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 51556 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   559 MBytes   467 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 48228 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.03 sec   558 MBytes   467 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 47600 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   557 MBytes   466 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 37252 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.05 sec   559 MBytes   467 Mbits/sec

After:

> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 40786 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.05 sec   572 MBytes   478 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 52482 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   571 MBytes   477 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 48370 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   572 MBytes   478 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 46086 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.05 sec   571 MBytes   476 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 46062 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   572 MBytes   478 Mbits/sec

Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
---
 drivers/net/ethernet/ibm/emac/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
index dac570f3c110..d476844bae3e 100644
--- a/drivers/net/ethernet/ibm/emac/core.c
+++ b/drivers/net/ethernet/ibm/emac/core.c
@@ -1727,6 +1727,7 @@ static inline int emac_rx_sg_append(struct emac_instance *dev, int slot)
 /* NAPI poll context */
 static int emac_poll_rx(void *param, int budget)
 {
+	LIST_HEAD(rx_list);
 	struct emac_instance *dev = param;
 	int slot = dev->rx_slot, received = 0;
 
@@ -1783,8 +1784,7 @@ static int emac_poll_rx(void *param, int budget)
 		skb->protocol = eth_type_trans(skb, dev->ndev);
 		emac_rx_csum(dev, skb, ctrl);
 
-		if (unlikely(netif_receive_skb(skb) == NET_RX_DROP))
-			++dev->estats.rx_dropped_stack;
+		list_add_tail(&skb->list, &rx_list);
 	next:
 		++dev->stats.rx_packets;
 	skip:
@@ -1828,6 +1828,8 @@ static int emac_poll_rx(void *param, int budget)
 		goto next;
 	}
 
+	netif_receive_skb_list(&rx_list);
+
 	if (received) {
 		DBG2(dev, "rx %d BDs" NL, received);
 		dev->rx_slot = slot;
-- 
2.46.2