Message-ID: <2eeef5a3-cbe7-7a01-489a-87c5ac00adf7@linutronix.de>
Date:   Tue, 21 Mar 2023 15:09:40 +0100
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To:     Donglin Peng <pengdonglin@sangfor.com.cn>, mhiramat@kernel.org,
        rostedt@goodmis.org, linux@armlinux.org.uk, mark.rutland@arm.com,
        will@kernel.org, catalin.marinas@arm.com, palmer@dabbelt.com,
        paul.walmsley@sifive.com, tglx@linutronix.de,
        dave.hansen@linux.intel.com, x86@kernel.org, mingo@redhat.com,
        xiehuan09@gmail.com, dinghui@sangfor.com.cn,
        huangcun@sangfor.com.cn, dolinux.peng@gmail.com
Cc:     linux-trace-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20230320131650.482594-1-pengdonglin@sangfor.com.cn>
 <20230320131650.482594-2-pengdonglin@sangfor.com.cn>
From:   Florian Kauer <florian.kauer@linutronix.de>
Subject: Re: [PATCH v5 1/2] function_graph: Support recording and printing the
 return value of function
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On 20.03.23 14:16, Donglin Peng wrote:
> When using the function_graph tracer to analyze system call failures,
> it can be time-consuming to analyze the trace logs and locate the kernel
> function that first returns an error. This change aims to simplify the
> process by recording the function return value to the 'retval' member of
> 'ftrace_graph_ent' and printing it when outputing the trace log.

I just came across your patch by pure luck and it helped me a lot
to trace down a problem I had, thanks!

So you can have my
Tested-by: Florian Kauer <florian.kauer@linutronix.de>
 
> New trace options are introduced: funcgraph-retval and graph_retval_hex.

I would personally prefer to have the second option scoped better, so for example
"funcgraph-retval-hex".

Greetings,
Florian