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Date: Thu, 15 Feb 2024 10:38:27 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>, Florent Revest
 <revest@chromium.org>, linux-trace-kernel@vger.kernel.org, LKML
 <linux-kernel@vger.kernel.org>, Martin KaFai Lau <martin.lau@linux.dev>,
 bpf <bpf@vger.kernel.org>, Sven Schnelle <svens@linux.ibm.com>, Alexei
 Starovoitov <ast@kernel.org>, Jiri Olsa <jolsa@kernel.org>, Arnaldo
 Carvalho de Melo <acme@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>,
 Alan Maguire <alan.maguire@oracle.com>, Mark Rutland
 <mark.rutland@arm.com>, Peter Zijlstra <peterz@infradead.org>, Thomas
 Gleixner <tglx@linutronix.de>, Guo Ren <guoren@kernel.org>
Subject: Re: [PATCH v7 22/36] function_graph: Add a new entry handler with
 parent_ip and ftrace_regs
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On Wed,  7 Feb 2024 00:11:34 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> 
> Add a new entry handler to fgraph_ops as 'entryregfunc'  which takes
> parent_ip and ftrace_regs. Note that the 'entryfunc' and 'entryregfunc'
> are mutual exclusive. You can set only one of them.
> 
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> ---

>  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> @@ -1070,6 +1075,7 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
>  struct fgraph_ops {
>  	trace_func_graph_ent_t		entryfunc;
>  	trace_func_graph_ret_t		retfunc;
> +	trace_func_graph_regs_ent_t	entryregfunc;

if entryfunc and entryregfunc are mutually exclusive, then why not make them
into a union?

struct fgraph_ops {
	union {
		trace_func_graph_ent_t		entryfunc;
		trace_func_graph_regs_ent_t	entryregfunc;
	};
	trace_func_graph_ret_t		retfunc;

-- Steve

	

>  	struct ftrace_ops		ops; /* for the hash lists */
>  	void				*private;
>  	int				idx;