linux-kernel - Re: [PATCH] ftrace: fix the file mode of graph tracer and stack tracer

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Date:   Thu, 8 Feb 2018 10:21:49 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Zhengyuan Liu <liuzhengyuan@...inos.cn>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org,
        liuzhengyuang521@...il.com, linx.z.chen@...el.com
Subject: Re: [PATCH] ftrace: fix the file mode of graph tracer and stack
 tracer

On Thu,  8 Feb 2018 09:41:53 +0800
Zhengyuan Liu <liuzhengyuan@...inos.cn> wrote:

> It's something looks weird that those files could be written by root
> but shows with no write permission by ll command.
> Chen LinX <linx.z.chen@...el.com> has sent a similar patch to fix
> graph function file mode in 2000,  I didn't get the reason why that
> patch wasn't applied so I resend it.
> 
> Signed-off-by: Zhengyuan Liu <liuzhengyuan@...inos.cn>
> ---
>  kernel/trace/ftrace.c      | 4 ++--
>  kernel/trace/trace_stack.c | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index ccdf366..fe903dc8 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -5513,10 +5513,10 @@ static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
>  	ftrace_create_filter_files(&global_ops, d_tracer);
>  
>  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> -	trace_create_file("set_graph_function", 0444, d_tracer,
> +	trace_create_file("set_graph_function", 0644, d_tracer,

Thanks for resending the patch.

What's interesting is that this doesn't seem to affect whether or not
root can write to the file. I wonder if that's a bug itself.

-- Steve

>  				    NULL,
>  				    &ftrace_graph_fops);
> -	trace_create_file("set_graph_notrace", 0444, d_tracer,
> +	trace_create_file("set_graph_notrace", 0644, d_tracer,
>  				    NULL,
>  				    &ftrace_graph_notrace_fops);
>  #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
> index 734accc..4356f14 100644
> --- a/kernel/trace/trace_stack.c
> +++ b/kernel/trace/trace_stack.c
> @@ -468,7 +468,7 @@ static __init int stack_trace_init(void)
>  			NULL, &stack_trace_fops);
>  
>  #ifdef CONFIG_DYNAMIC_FTRACE
> -	trace_create_file("stack_trace_filter", 0444, d_tracer,
> +	trace_create_file("stack_trace_filter", 0644, d_tracer,
>  			  &trace_ops, &stack_trace_filter_fops);
>  #endif
>