net: mvneta: fix improper tx queue usage in mvneta_tx()

Gregory CLEMENT
2013-04-15T11:50:37Z

Hi Willy

On 04/15/2013 08:35 AM, Willy Tarreau wrote:
> From 4f2069c92a27790e6071dc2a80f92c166e0b0ca4 Mon Sep 17 00:00:00 2001
> From: Willy Tarreau <w@1wt.eu>
> Date: Thu, 11 Apr 2013 23:00:37 +0200
> Subject: net: mvneta: fix improper tx queue usage in mvneta_tx()
>
> mvneta_tx() was using a static tx queue number causing crashes as
> soon as a little bit of traffic was sent via the interface, because
> it is normally expected that the same queue should be used as in
> dev_queue_xmit().
>
> As suggested by Ben Hutchings, let's use skb_get_queue_mapping() to
> get the proper Tx queue number, and use alloc_etherdev_mqs() instead
> of alloc_etherdev_mq() to create the queues.
>
> Both my Mirabox and my OpenBlocks AX3 used to crash without this patch
> and don't anymore with it. The issue appeared in 3.8 but became more
> visible after the fix allowing GSO to be enabled.
>
> Original work was done by Dmitri Epshtein and Thomas Petazzoni. I
> just adapted it to take care of Ben's comments.

Thanks for this work. I have tested on a DB-MV784MP-GP board in SMP
with 4 CPUs. Without this patch a "iperf -P 4" lead to a kernel crash
in 80% of the case and to a hang in the remaining cases. Now after
a dozen of tests on this board, I didn't see any crash or hang.
You can add my
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

Thanks,

>
> Signed-off-by: Willy Tarreau <w@1wt.eu>
> Cc: Dmitri Epshtein <dima@marvell.com>
> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
> Cc: Ben Hutchings <bhutchings@solarflare.com>
> ---
> drivers/net/ethernet/marvell/mvneta.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 1e628ce..a47a097 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -374,7 +374,6 @@ static int rxq_number = 8;
> static int txq_number = 8;
>
> static int rxq_def;
> -static int txq_def;
>
> #define MVNETA_DRIVER_NAME "mvneta"
> #define MVNETA_DRIVER_VERSION "1.0"
> @@ -1475,7 +1474,8 @@ error:
> static int mvneta_tx(struct sk_buff *skb, struct net_device *dev)
> {
> struct mvneta_port *pp = netdev_priv(dev);
> - struct mvneta_tx_queue *txq = &pp->txqs[txq_def];
> + u16 txq_id = skb_get_queue_mapping(skb);
> + struct mvneta_tx_queue *txq = &pp->txqs[txq_id];
> struct mvneta_tx_desc *tx_desc;
> struct netdev_queue *nq;
> int frags = 0;
> @@ -1485,7 +1485,7 @@ static int mvneta_tx(struct sk_buff *skb, struct net_device *dev)
> goto out;
>
> frags = skb_shinfo(skb)->nr_frags + 1;
> - nq = netdev_get_tx_queue(dev, txq_def);
> + nq = netdev_get_tx_queue(dev, txq_id);
>
> /* Get a descriptor for the first part of the packet */
> tx_desc = mvneta_txq_next_desc_get(txq);
> @@ -2689,7 +2689,7 @@ static int mvneta_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> - dev = alloc_etherdev_mq(sizeof(struct mvneta_port), 8);
> + dev = alloc_etherdev_mqs(sizeof(struct mvneta_port), txq_number, rxq_number);
> if (!dev)
> return -ENOMEM;
>
> @@ -2844,4 +2844,3 @@ module_param(rxq_number, int, S_IRUGO);
> module_param(txq_number, int, S_IRUGO);
>
> module_param(rxq_def, int, S_IRUGO);
> -module_param(txq_def, int, S_IRUGO);
>

--
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.