From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexei Starovoitov <ast@fb.com>
Subject: Re: [PATCH v5 bpf-next 06/10] tracepoint: compute num_args at build
 time
Date: Mon, 26 Mar 2018 11:39:05 -0700
Message-ID: <543f953a-8284-68f0-6a22-ec2d5f247199@fb.com>
References: <20180324023038.938665-1-ast@fb.com>
 <1787605856.4574.1522077244597.JavaMail.zimbra@efficios.com>
 <5bcacdb5-e72f-b67a-4884-61fcedf0938a@fb.com>
 <523311773.184.1522079745421.JavaMail.zimbra@efficios.com>
 <f39181e0-3d46-2154-044c-dfc985053b3a@fb.com>
 <1055377367.195.1522081045131.JavaMail.zimbra@efficios.com>
 <89fbc745-c290-c82c-a837-8998cf2988e7@fb.com>
 <20180326123530.66ced6ae@gandalf.local.home>
 <1218234422.259.1522083422808.JavaMail.zimbra@efficios.com>
 <17073efa-d833-7348-bef1-79376ad43bc6@fb.com>
 <20180326141104.6d63660a@gandalf.local.home>
Mime-Version: 1.0
Content-Type: text/plain; charset="windows-1252"; format=flowed
Content-Transfer-Encoding: 7bit
Return-path: <netdev-owner@vger.kernel.org>
In-Reply-To: <20180326141104.6d63660a@gandalf.local.home>
Sender: netdev-owner@vger.kernel.org
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, "David S. Miller" <davem@davemloft.net>, Daniel Borkmann <daniel@iogearbox.net>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <peterz@infradead.org>, netdev <netdev@vger.kernel.org>, kernel-team <kernel-team@fb.com>, linux-api <linux-api@vger.kernel.org>, "Frank Ch. Eigler" <fche@redhat.com>
List-Id: linux-api@vger.kernel.org

On 3/26/18 11:11 AM, Steven Rostedt wrote:
> On Mon, 26 Mar 2018 10:55:51 -0700
> Alexei Starovoitov <ast@fb.com> wrote:
>
>> An email ago you were ok to s/return/return NULL/ in your out-of-tree
>> module, but now flip flop to add new function approach just to
>> reduce the work you need to do in lttng?
>> We're not talking about changing __kmalloc signature here.
>> My patch extends for_each_kernel_tracepoint() api similar to other
>> for_each_*() iterators and improves possible uses of it.
>
> Alexei, do you have another use case for using
> for_each_kernel_tracepoint() other than the find_tp? If so, then I'm
> sure Mathieu can handle the change.
>
> But I think it's cleaner to add a tracepoint_find_by_name() function.
> If you come up with another use case for using the for_each* function
> then we'll consider changing it then.

another use case ?! Frankly such reasoning smells.

I'm fine doing quick followup patch to add tracepoint_find_by_name()
and restore 'return void' behavior of for_each_kernel_tracepoint's
callback, but I'm struggling to accept the precedent it will create
that all exported functions of kernel/tracepoint.c are really
lttng extensions and we cannot easily change them.
I'd like to hear Linus take on this.