netdev - Re: [PATCH net-next] net: Print real skb addresses for all net events

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Date:   Mon, 27 Jun 2022 12:27:37 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     "Subash Abhinov Kasiviswanathan (KS)" <quic_subashab@...cinc.com>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        netdev <netdev@...r.kernel.org>, quic_jzenner@...cinc.com,
        Cong Wang <cong.wang@...edance.com>, qitao.xu@...edance.com,
        Sean Tranchetti <quic_stranche@...cinc.com>
Subject: Re: [PATCH net-next] net: Print real skb addresses for all net events

On Fri, Jun 24, 2022 at 02:48:24AM -0600, Subash Abhinov Kasiviswanathan (KS) wrote:
> 
> 
> On 6/24/2022 12:27 AM, Eric Dumazet wrote:
> > On Fri, Jun 24, 2022 at 8:09 AM Subash Abhinov Kasiviswanathan
> > <quic_subashab@...cinc.com> wrote:
> > > 
> > > Commit 65875073eddd ("net: use %px to print skb address in trace_netif_receive_skb")
> > > added support for printing the real addresses for the events using
> > > net_dev_template.
> > > 
> > 
> > It is not clear why the 'real address' is needed in trace events.
> > 
> > I would rather do the opposite.
> > 
> 
> We don't need the real address. We just need the events to display in the
> same format - hashed address is fine.
> 
> > diff --git a/include/trace/events/net.h b/include/trace/events/net.h
> > index 032b431b987b63b5fab1d3c763643d6192f2c325..da611a7aaf970f541949cdd87ac9203c4c7e81b1
> > 100644
> > --- a/include/trace/events/net.h
> > +++ b/include/trace/events/net.h
> > @@ -136,7 +136,7 @@ DECLARE_EVENT_CLASS(net_dev_template,
> >                  __assign_str(name, skb->dev->name);
> >          ),
> > 
> > -       TP_printk("dev=%s skbaddr=%px len=%u",
> > +       TP_printk("dev=%s skbaddr=%p len=%u",
> >                  __get_str(name), __entry->skbaddr, __entry->len)
> >   )
> > 
> 
> Qitao / Cong, do you have any concerns as it ends up reverting commit
> 65875073eddd ("net: use %px to print skb address in
> trace_netif_receive_skb")

Yes, see this example:
https://lists.openwall.net/netdev/2021/07/28/24

Thanks.