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Message-ID: <1307123978.2789.53.camel@bwh-desktop>
Date: Fri, 03 Jun 2011 18:59:38 +0100
From: Ben Hutchings <bhutchings@...arflare.com>
To: Neil Horman <nhorman@...driver.com>
Cc: netdev@...r.kernel.org, Jay Vosburgh <fubar@...ibm.com>,
Andy Gospodarek <andy@...yhouse.net>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] bonding: reset queue mapping prior to transmission to
physical device (v3)
On Fri, 2011-06-03 at 13:32 -0400, Neil Horman wrote:
> The bonding driver is multiqueue enabled, in which each queue represents a slave
> to enable optional steering of output frames to given slaves against the default
> output policy. However, it needs to reset the skb->queue_mapping prior to
> queuing to the physical device or the physical slave (if it is multiqueue) could
> wind up transmitting on an unintended tx queue
>
> Change Notes:
> v2) Based on first pass review, updated the patch to restore the origional queue
> mapping that was found in bond_select_queue, rather than simply resetting to
> zero. This preserves the value of queue_mapping when it was set on receive in
> the forwarding case which is desireable.
>
> v3) Fixed spelling an casting error in skb->cb
>
> Signed-off-by: Neil Horman <nhorman@...driver.com>
> CC: Jay Vosburgh <fubar@...ibm.com>
> CC: Andy Gospodarek <andy@...yhouse.net>
> CC: "David S. Miller" <davem@...emloft.net>
> ---
> drivers/net/bonding/bond_main.c | 10 ++++++++++
> 1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 17b4dd9..dbb1048 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -400,6 +400,11 @@ int bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb,
> {
> skb->dev = slave_dev;
> skb->priority = 1;
> + /*
> + *restore the origional mapping
> + */
> + skb_set_queue_mapping(skb, ((u16 *)skb->cb)[0]);
> +
> if (unlikely(netpoll_tx_running(slave_dev)))
> bond_netpoll_send_skb(bond_get_slave_by_dev(bond, slave_dev), skb);
> else
> @@ -4216,6 +4221,11 @@ static u16 bond_select_queue(struct net_device *dev, struct sk_buff *skb)
> */
> u16 txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) : 0;
>
> + /*
> + * Save the original txq to restore before passing to the driver
> + */
> + ((u16 *)skb->cb)[0] = txq;
> +
> if (unlikely(txq >= dev->real_num_tx_queues)) {
> do {
> txq -= dev->real_num_tx_queues;
I should have read this more thoroughly before - I'm afraid this is
still not quite right as skb_get_rx_queue() will subtract 1. You need
to save skb_get_queue_mapping() rather than txq.
But skb_{get,set}_queue_mapping() seem to be meant to deal with TX queue
numbers so maybe it's better to save and restore skb->queue_mapping
directly.
Ben.
--
Ben Hutchings, Senior Software Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
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