linux-kernel - Re: [PATCH 1/2] perf: Fix checking of duplicate probe to give proper hint

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Message-Id: <20200226073443.3f6b44422104873dc0397d0e@kernel.org>
Date:   Wed, 26 Feb 2020 07:34:43 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     <zhe.he@...driver.com>
Cc:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...hat.com>, <namhyung@...nel.org>,
        <kstewart@...uxfoundation.org>, <tglx@...utronix.de>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] perf: Fix checking of duplicate probe to give
 proper hint

Hi,

Thanks for reporting. This bug has been reported and I should fixed last year...

https://lkml.org/lkml/2019/12/3/136

Arnaldo, haven't you picked it yet?

Thank you,


On Tue, 25 Feb 2020 22:41:42 +0800
<zhe.he@...driver.com> wrote:

> From: He Zhe <zhe.he@...driver.com>
> 
> Since commit 72363540c009 ("perf probe: Support multiprobe event") and its
> series, if there are multiple probes for one event,
> __probe_file__get_namelist would return -EEXIST and cause the following
> failure without proper hint, due to adding existing entry to output list.
> 
> root@...uarm64:~# perf probe -x /lib64/libc.so.6 free
> Added new events:
>   probe_libc:free      (on free in /lib64/libc-2.31.so)
>   probe_libc:free      (on free in /lib64/libc-2.31.so)
> 
> You can now use it in all perf tools, such as:
> 
>         perf record -e probe_libc:free -aR sleep 1
> 
> root@...uarm64:~# perf probe -l
>   probe_libc:free      (on free@plt in /lib64/libc-2.31.so)
>   probe_libc:free      (on cfree in /lib64/libc-2.31.so)
> root@...uarm64:~# perf probe -x /lib64/libc.so.6 free
>   Error: Failed to add events.
> 
> As we just want to check if there is any probe with the same name, -EEXIST
> can be ignored, so we can have the right hint as before.
> 
> root@...uarm64:~# perf probe -x /lib64/libc.so.6 free
> Error: event "free" already exists.
>  Hint: Remove existing event by 'perf probe -d'
>        or force duplicates by 'perf probe -f'
>        or set 'force=yes' in BPF source.
>   Error: Failed to add events.
> 
> Signed-off-by: He Zhe <zhe.he@...driver.com>
> ---
>  tools/perf/util/probe-file.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 5003ba403345..cf44c05f89c1 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -201,10 +201,16 @@ static struct strlist *__probe_file__get_namelist(int fd, bool include_group)
>  		if (include_group) {
>  			ret = e_snprintf(buf, 128, "%s:%s", tev.group,
>  					tev.event);
> -			if (ret >= 0)
> +			if (ret >= 0) {
>  				ret = strlist__add(sl, buf);
> -		} else
> +				if (ret == -EEXIST)
> +					ret = 0;
> +			}
> +		} else {
>  			ret = strlist__add(sl, tev.event);
> +			if (ret == -EEXIST)
> +				ret = 0;
> +		}
>  		clear_probe_trace_event(&tev);
>  		if (ret < 0)
>  			break;
> -- 
> 2.24.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>