linux-kernel - Re: [PATCH v2] trace: Remove get/put_cpu() from function_trace

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Date:   Mon, 11 Jan 2021 18:51:29 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Qiujun Huang <hqjagain@...il.com>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] trace: Remove get/put_cpu() from function_trace_init

On Wed, 30 Dec 2020 22:05:21 +0800
Qiujun Huang <hqjagain@...il.com> wrote:

> Since commit b6f11df26fdc ("trace: Call tracing_reset_online_cpus before
> tracer->init()"), get/put_cpu() are not needed anymore.
> We can use raw_smp_processor_id() instead.

I added both your patches (this one and the trace_ignore_this_task()
kernel-doc fix to my queue.

Thanks!

-- Steve

> 
> Signed-off-by: Qiujun Huang <hqjagain@...il.com>
> ---
> v2:
> Use raw_smp_processor_id() instead of smp_processor_id()
> ---
>  kernel/trace/trace_functions.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> index c5095dd28e20..f67aec5bb771 100644
> --- a/kernel/trace/trace_functions.c
> +++ b/kernel/trace/trace_functions.c
> @@ -106,8 +106,7 @@ static int function_trace_init(struct trace_array *tr)
>  
>  	ftrace_init_array_ops(tr, func);
>  
> -	tr->array_buffer.cpu = get_cpu();
> -	put_cpu();
> +	tr->array_buffer.cpu = raw_smp_processor_id();
>  
>  	tracing_start_cmdline_record();
>  	tracing_start_function_trace(tr);