netdev - Re: [PATCH v2] net: Add trace events for all receive exit points

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Date:   Mon, 12 Nov 2018 15:56:17 -0500 (EST)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     rostedt <rostedt@...dmis.org>
Cc:     Geneviève Bastien <gbastien@...satic.net>,
        "David S. Miller" <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v2] net: Add trace events for all receive exit points

----- On Nov 12, 2018, at 3:46 PM, Mathieu Desnoyers mathieu.desnoyers@...icios.com wrote:

> ----- On Nov 12, 2018, at 3:40 PM, rostedt rostedt@...dmis.org wrote:
> 
>> On Mon, 12 Nov 2018 15:20:55 -0500 (EST)
>> Mathieu Desnoyers <mathieu.desnoyers@...icios.com> wrote:
>> 
>>> 
>>> Hrm, looking at this again, I notice that there is a single DEFINE_EVENT
>>> using net_dev_template_simple.
>>> 
>>> We could simply turn netif_receive_skb_list_exit into a TRACE_EVENT(),
>>> remove the net_dev_template_simple, and rename the net_dev_template_return
>>> to net_dev_template ?
>> 
>> This too is only cosmetic and doesn't affect the code at all, because a
>> TRACE_EVENT() is really just:
>> 
>> #define TRACE_EVENT(name, proto, args, tstruct, assign, print) \
>>	DECLARE_EVENT_CLASS(name,			       \
>>			     PARAMS(proto),		       \
>>			     PARAMS(args),		       \
>>			     PARAMS(tstruct),		       \
>>			     PARAMS(assign),		       \
>>			     PARAMS(print));		       \
>>	DEFINE_EVENT(name, name, PARAMS(proto), PARAMS(args));
>> 
>> -- Steve
>> 
> 
> Of course.
> 
> I also notice that in two cases, a "gro_result_t" is implicitly cast
> to "int". I usually frown upon this kind of stuff, because it's asking
> for trouble if gro_result_t typedef to something else than "int" in the
> future.
> 
> I would recommend going for two templates, one which takes a "int"
> ret parameter, and the other a "gro_result_t" ret parameter.
> 
> Or am I being too cautious ?

Digging further, gro_result_t maps to:

enum gro_result {
        GRO_MERGED,
        GRO_MERGED_FREE,
        GRO_HELD,
        GRO_NORMAL,
        GRO_DROP,
        GRO_CONSUMED,
};
typedef enum gro_result gro_result_t;

So we should add a TRACE_DEFINE_ENUM() for those.

Thanks,

Mathieu



> 
> Thanks,
> 
> Mathieu
> 
> 
>>> 
>>> It's pretty clear from the prototype that it expects a "ret" argument,
>>> so I don't see the need to also state it in the template name.
>>> 
> 
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com