netdev - Re: [PATCH v3 bpf-next] cpumap: bulk skb using netif_receive_skb

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Date:   Tue, 20 Apr 2021 19:09:38 +0200
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Lorenzo Bianconi <lorenzo@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org,
        ast@...nel.org, daniel@...earbox.net, song@...nel.org,
        toke@...hat.com
Subject: Re: [PATCH v3 bpf-next] cpumap: bulk skb using netif_receive_skb_list

[...]
> > +	TP_ARGS(map_id, processed, sched, xdp_stats),
> >  
> >  	TP_STRUCT__entry(
> >  		__field(int, map_id)
> >  		__field(u32, act)
> >  		__field(int, cpu)
> > -		__field(unsigned int, drops)
> >  		__field(unsigned int, processed)
> 
> So, struct member @processed will takeover the room for @drops.
> 
> Can you please test how an old xdp_monitor program will react to this?
> Will it fail, or extract and show wrong values?

Ack, right. I think we should keep the struct layout in order to maintain
back-compatibility. I will fix it in v4.

> 
> The xdp_mointor tool is in several external git repos:
> 
>  https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/samples/bpf/xdp_monitor_kern.c
>  https://github.com/xdp-project/xdp-tutorial/tree/master/tracing02-xdp-monitor
> 
> Do you have any plans for fixing those tools?

I update xdp_monitor_{kern,user}.c and xdp_redirect_cpu_{kern,user}.c in the
patch. Do you mean to post a dedicated patch for xdp-project tutorial?

Regards,
Lorenzo

> 
> 
> 
> 
> -- 
> Best regards,
>   Jesper Dangaard Brouer
>   MSc.CS, Principal Kernel Engineer at Red Hat
>   LinkedIn: http://www.linkedin.com/in/brouer
> 

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