linux-kernel - Re: [PATCH 4/4] perf probe: Propagate error code when write(2) failed

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Date:	Mon, 12 Jan 2015 20:17:52 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>
Subject: Re: [PATCH 4/4] perf probe: Propagate error code when write(2)
 failed

(2015/01/10 19:33), Namhyung Kim wrote:
> When it failed to write probe commands to the probe_event file in
> debugfs, it needs to propagate the error code properly.  Current code
> blindly uses the return value of the write(2) so it always uses
> -1 (-EPERM) and it might confuse users.
> 

Good catch! :)

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/probe-event.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 6fe5aa357efc..ddc295885af0 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -2052,9 +2052,11 @@ static int write_probe_trace_event(int fd, struct probe_trace_event *tev)
>  	pr_debug("Writing event: %s\n", buf);
>  	if (!probe_event_dry_run) {
>  		ret = write(fd, buf, strlen(buf));
> -		if (ret <= 0)
> +		if (ret <= 0) {
> +			ret = -errno;
>  			pr_warning("Failed to write event: %s\n",
>  				   strerror_r(errno, sbuf, sizeof(sbuf)));
> +		}
>  	}
>  	free(buf);
>  	return ret;
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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