linux-kernel - Re: [PATCH v2 6/6] stm class: ftrace: use different channel accroding to CPU

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Message-ID: <20200728002823.GA10290@codeaurora.org>
Date:   Tue, 28 Jul 2020 08:28:23 +0800
From:   Tingwei Zhang <tingweiz@...eaurora.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Tingwei Zhang <tingwei@...eaurora.org>,
        Ingo Molnar <mingo@...hat.com>, tsoni@...eaurora.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Mao Jinlong <jinlmao@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 6/6] stm class: ftrace: use different channel
 accroding to CPU

Hi Steve,
On Tue, Jul 28, 2020 at 03:08:12AM +0800, Steven Rostedt wrote:
> On Sun, 26 Jul 2020 10:59:31 +0800
> Tingwei Zhang <tingwei@...eaurora.org> wrote:
> 
> > --- a/drivers/hwtracing/stm/ftrace.c
> > +++ b/drivers/hwtracing/stm/ftrace.c
> > @@ -37,8 +37,9 @@ static void notrace
> >  stm_ftrace_write(struct trace_export *export, const void *buf, unsigned
> int len)
> >  {
> >  	struct stm_ftrace *stm = container_of(export, struct stm_ftrace,
> ftrace);
> > +	unsigned int cpu = smp_processor_id();
> 
> Probably should add a comment to the above stating that this is called
> from the tracing system with preemption disabled.
> 

Good point. I'll add that comment in next revision.

Thanks,
Tingwei

> Other than my two comments:
> 
> Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> 
> -- Steve
> 
> 
> >  
> > -	stm_source_write(&stm->data, STM_FTRACE_CHAN, buf, len);
> > +	stm_source_write(&stm->data, STM_FTRACE_CHAN + cpu, buf, len);
> >  }
> >  
> >  static int stm_ftrace_link(struct stm_source_data *data)