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Date:   Mon, 5 Sep 2022 10:38:08 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Eric Dumazet <edumazet@google.com>
Cc:     Menglong Dong <menglong8.dong@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>,
        David Miller <davem@davemloft.net>,
        Paolo Abeni <pabeni@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Menglong Dong <imagedong@tencent.com>,
        David Ahern <dsahern@kernel.org>,
        Hao Peng <flyingpeng@tencent.com>,
        Dongli Zhang <dongli.zhang@oracle.com>, robh@kernel.org,
        Pavel Begunkov <asml.silence@gmail.com>,
        Luiz Augusto von Dentz <luiz.von.dentz@intel.com>,
        Vasily Averin <vasily.averin@linux.dev>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next v2] net: skb: export skb drop reaons to user by
 TRACE_DEFINE_ENUM
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        <CANn89iK7Mm4aPpr1-VM5OgicuHrHjo9nm9P9bYgOKKH9yczFzg@mail.gmail.com>
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On Fri, 2 Sep 2022 08:43:07 -0700
Eric Dumazet <edumazet@google.com> wrote:

> > ---
> > v2:
> > - undef FN/FNe after use it (Jakub Kicinski)  
> 
> I would love some feedback from Steven :)

The undef should be fine. I usually do not, but that's more of a preference
than a rule.

As long as the undef is done after the C portion of where the macro is used:

+#undef FN
+#define FN(reason)	TRACE_DEFINE_ENUM(SKB_DROP_REASON_##reason);
+DEFINE_DROP_REASON(FN, FN) <<<--- C portion

+#undef FN
+#undef FNe
+#define FN(reason)	{ SKB_DROP_REASON_##reason, #reason },
+#define FNe(reason)	{ SKB_DROP_REASON_##reason, #reason }
+
 /*
  * Tracepoint for free an sk_buff:
  */
@@ -35,9 +44,13 @@ TRACE_EVENT(kfree_skb,
 
 	TP_printk("skbaddr=%p protocol=%u location=%p reason: %s",
 		  __entry->skbaddr, __entry->protocol, __entry->location,
-		  drop_reasons[__entry->reason])
+		  __print_symbolic(__entry->reason,
+				   DEFINE_DROP_REASON(FN, FNe)))  <<<--- C portion
 );
 
+#undef FN
+#undef FNe

So for this part: Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve