[PATCH v1 6/7] net: mvneta: Don't use GRO on Armada 3720

Hi,

On Thu, 9 Aug 2018 12:40:41 +0800 Jisheng Zhang wrote:

+ more people

On Wed,  8 Aug 2018 17:27:05 +0200 Marek Beh?n wrote:

quoted

For some reason on Armada 3720 boards (EspressoBin and Turris Mox) the
networking driver behaves weirdly when using napi_gro_receive.

For example downloading a big file from a local network (low ping) is
fast, but when downloading from a remote server (higher ping), the
download speed is at first high but drops rapidly to almost nothing or
absolutely nothing.  

We also met this issue on some berlin platforms. I tried to fix the bug,
but no clue so far.

quoted

This is fixed when using netif_receive_skb instead of napi_gro_receive.  

This is a workaround. The good news is this workaround also fixes the issue
we saw on berlin.

quoted

Signed-off-by: Marek Behun <redacted>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: netdev at vger.kernel.org

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 0ad2f3f7da85..27f3017d94c5 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c

@@ -1959,7 +1959,10 @@ static int mvneta_rx_swbm(struct mvneta_port *pp, int rx_todo,
 
 			skb->protocol = eth_type_trans(skb, dev);
 			mvneta_rx_csum(pp, rx_status, skb);
-			napi_gro_receive(&port->napi, skb);
+			if (pp->neta_armada3700)
+				netif_receive_skb(skb);
+			else
+				napi_gro_receive(&port->napi, skb);

I think I found the root cause, if neta_armada3700 is true, the port got from
this_cpu_ptr(pp->ports) is invalid, this is bug... I'll cook a patch for this

Thanks

quoted

 
 			rcvd_pkts++;
 			rcvd_bytes += rx_bytes;

@@ -2001,7 +2004,10 @@ static int mvneta_rx_swbm(struct mvneta_port *pp, int rx_todo,
 
 		mvneta_rx_csum(pp, rx_status, skb);
 
-		napi_gro_receive(&port->napi, skb);
+		if (pp->neta_armada3700)
+			netif_receive_skb(skb);
+		else
+			napi_gro_receive(&port->napi, skb);
 	}
 
 	if (rcvd_pkts) {