Subject: Re: [PATCH] bond: Don't set skb->queue_mapping in netpoll.

From: Sergei Shtylyov <[email-masked]>
Date: Fri, 16 Aug 2013 01:07:52 +0400

On 08/15/2013 12:36 PM, Tao Ma wrote:

> From: Tao Ma <[email-masked]>

> When we are using netpoll, we don't go through the normal
> transmit process. In this case, bond_select_queue is not called
> and qdisc_skb_cb(skb)->slave_dev_queue_mapping isn't set.

> So when netpoll_send_skb_on_dev calls ndo_start_xmit and we
> enter bond_dev_queue_xmit, we will set skb->queue_mapping to
> an invalid value and in some cases cause the driver panic the
> kernel(We meet with bnx2 panic because of a very large queue_mapping).

> This patch skip skb->queue_mapping if we find we are in netpoll.

> CC: "David S. Miller" <[email-masked]>
> CC: Cong Wang <[email-masked]>
> CC: Eric Dumazet <[email-masked]>
> Signed-off-by: Tao Ma <[email-masked]>
> ---
>   drivers/net/bonding/bond_main.c |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)

> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 07f257d..97b2f52 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -405,12 +405,13 @@ int bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb,
>
>   	BUILD_BUG_ON(sizeof(skb->queue_mapping) !=
>   		     sizeof(qdisc_skb_cb(skb)->slave_dev_queue_mapping));
> -	skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;
>
>   	if (unlikely(netpoll_tx_running(bond->dev)))
>   		bond_netpoll_send_skb(bond_get_slave_by_dev(bond, slave_dev), skb);
> -	else
> +	else {
> +		skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;
>   		dev_queue_xmit(skb);
> +	}

     According to Documentation/CodingStyle, both arms of the *if* statement 
should have {} if one arm has them.

WBR, Sergei