netdev - Re: [PATCH net v2] net/sched: act

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Date:   Mon, 24 Apr 2023 20:36:02 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Victor Nogueira <victor@...atatu.com>
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, netdev@...r.kernel.org, jhs@...atatu.com,
        xiyou.wangcong@...il.com, jiri@...nulli.us, kernel@...atatu.com
Subject: Re: [PATCH net v2] net/sched: act_mirred: Add carrier check

On Mon, Apr 24, 2023 at 05:08:32PM +0000, Victor Nogueira wrote:
> There are cases where the device is adminstratively UP, but operationally 
> down. For example, we have a physical device (Nvidia ConnectX-6 Dx, 25Gbps)
> who's cable was pulled out, here is its ip link output:
> 
> 5: ens2f1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc mq state DOWN mode DEFAULT group default qlen 1000
>     link/ether b8:ce:f6:4b:68:35 brd ff:ff:ff:ff:ff:ff
>     altname enp179s0f1np1
> 
> As you can see, it's administratively UP but operationally down.
> In this case, sending a packet to this port caused a nasty kernel hang (so
> nasty that we were unable to capture it). Aborting a transmit based on
> operational status (in addition to administrative status) fixes the issue.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> 

Please no blank line between tags.

> Acked-by: Jamal Hadi Salim <jhs@...atatu.com>
> Signed-off-by: Victor Nogueira <victor@...atatu.com>
> ---
>  net/sched/act_mirred.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

It will be great to have changelog to see the changes between versions.

Thanks

> 
> diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
> index ec43764e92e7..0a711c184c29 100644
> --- a/net/sched/act_mirred.c
> +++ b/net/sched/act_mirred.c
> @@ -264,7 +264,7 @@ TC_INDIRECT_SCOPE int tcf_mirred_act(struct sk_buff *skb,
>  		goto out;
>  	}
>  
> -	if (unlikely(!(dev->flags & IFF_UP))) {
> +	if (unlikely(!(dev->flags & IFF_UP)) || !netif_carrier_ok(dev)) {
>  		net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
>  				       dev->name);
>  		goto out;
> -- 
> 2.25.1
>