NFS/TCP/IPv6 acting strangely in 4.2

[Willy Tarreau]

Hi,

On Wed, Sep 16, 2015 at 06:53:57AM +0000, Damien Thébault wrote:
> On Fri, 2015-09-11 at 12:38 +0100, Russell King - ARM Linux wrote:
> > I have a recent Marvell Armada 388 board here which uses the mvneta
> > driver.  I'm seeing some weird effects with NFS with it acting as a
> > client.
> 
> Hello,
> 
> I'm upgrading a Marvelle Armada 370 board using the mvneta driver from
> 4.0 to 4.2 and noticed issues with NFS booting.
> Basically, most of the time init returns with an error code, or
> programs segfault or throw illegal instructions.
> 
> Since it worked fine on 4.0 I bisected until I found commit
> a84e32894191cfcbffa54180d78d7d4654d56c20 "net: mvneta: fix refilling
> for Rx DMA buffers".
> 
> If I revert this commit, everything seems to get back to normal.
> Could you try it ? The two issues look very similar.

I'm not sure but I'm seeing that the accounting was changed by this
patch without being certain of the implications; if the revert above
works, it would be nice to try to only apply this just to see if
that's indeed an accounting error or not :

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 62e48bc..4205867 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1463,6 +1463,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 {
 	struct net_device *dev = pp->dev;
 	int rx_done;
+	int missed = 0;
 	u32 rcvd_pkts = 0;
 	u32 rcvd_bytes = 0;
 
@@ -1527,6 +1528,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 		if (err) {
 			netdev_err(dev, "Linux processing - Can't refill\n");
 			rxq->missed++;
+			missed++;
 			goto err_drop_frame;
 		}
 
@@ -1561,7 +1563,7 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 	}
 
 	/* Update rxq management counters */
-	mvneta_rxq_desc_num_update(pp, rxq, rx_done, rx_done);
+	mvneta_rxq_desc_num_update(pp, rxq, rx_done, rx_done - missed);
 
 	return rx_done;
 }

Regards,
Willy