Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
Date:   Fri, 22 Apr 2022 11:52:34 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     patrick wang <patrick.wang.shcn@gmail.com>
Cc:     paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com,
        josh@joshtriplett.org, mathieu.desnoyers@efficios.com,
        jiangshanlai@gmail.com, joel@joelfernandes.org,
        rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rcu: ftrace: avoid tracing a few functions executed in
 multi_cpu_stop()
Message-ID: <20220422115234.613436e4@gandalf.local.home>
In-Reply-To: <CAGcnep9Ez-S962vukR_a=otzcSxDRo5HUW2vG_YCBanCfURGXw@mail.gmail.com>
References: <20220418043735.11441-1-patrick.wang.shcn@gmail.com>
        <20220418143404.55c8fcab@gandalf.local.home>
        <CAGcnep8bH4Nncbt3t+VRLff35ZyD8JyzHcEgkq-u6TEq47jqzQ@mail.gmail.com>
        <CAGcnep_Gx+3KiUvDVronYKn_divU3OM-RQEOPZakv7MRYh4EJw@mail.gmail.com>
        <20220420114454.69ab108c@gandalf.local.home>
        <20220420122633.55d4ff6b@gandalf.local.home>
        <CAGcnep86pd2trfTovU8_z1msOstx7gKCdndm=pHLDGTy+_K7=g@mail.gmail.com>
        <20220421085047.2cb8edf9@gandalf.local.home>
        <CAGcnep9Ez-S962vukR_a=otzcSxDRo5HUW2vG_YCBanCfURGXw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Fri, 22 Apr 2022 18:45:46 +0800
patrick wang <patrick.wang.shcn@gmail.com> wrote:

> Yes, and not just RISC-V. It's arch-independent. It's the internal change of
> stop machine implementation.
> 
> ----------------------------------------------------------------
> Former stop machine wait loop:
> do {
>     cpu_relax(); => macro
>     ...
> } while (curstate != STOPMACHINE_EXIT);
> -----------------------------------------------------------------
> Current stop machine wait loop:
> do {
>     stop_machine_yield(cpumask); => function (notraced)
>     ...
>     touch_nmi_watchdog(); => function (notraced, inside calls also notraced)
>     ...
>     rcu_momentary_dyntick_idle(); => function (notraced, inside calls traced)
> } while (curstate != MULTI_STOP_EXIT);
> ------------------------------------------------------------------

That makes much more sense. Can you add that to the change log.

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

-- Steve