linux-kernel - Re: [PATCH 07/12] perf script: Pad dso name for --call-trace

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Message-ID: <37A033AF-567C-47F5-8FBB-DBD26ED1BD13@fb.com>
Date:   Tue, 7 May 2019 18:29:07 +0000
From:   Song Liu <songliubraving@...com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        "Namhyung Kim" <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Stanislav Fomichev <sdf@...ichev.me>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 07/12] perf script: Pad dso name for --call-trace



> On May 7, 2019, at 1:13 AM, Jiri Olsa <jolsa@...hat.com> wrote:
> 
> On Mon, May 06, 2019 at 09:38:55PM +0000, Song Liu wrote:
> 
> SNIP
> 
>>> 
>>> Link: http://lkml.kernel.org/n/tip-99g9rg4p20a1o99vr0nkjhq8@git.kernel.org
>>> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
>>> ---
>>> tools/include/linux/kernel.h  |  1 +
>>> tools/lib/vsprintf.c          | 19 +++++++++++++++++++
>>> tools/perf/builtin-script.c   |  1 +
>>> tools/perf/util/map.c         |  6 ++++++
>>> tools/perf/util/symbol_conf.h |  1 +
>>> 5 files changed, 28 insertions(+)
>>> 
>>> diff --git a/tools/include/linux/kernel.h b/tools/include/linux/kernel.h
>>> index 857d9e22826e..cba226948a0c 100644
>>> --- a/tools/include/linux/kernel.h
>>> +++ b/tools/include/linux/kernel.h
>>> @@ -102,6 +102,7 @@
>>> 
>>> int vscnprintf(char *buf, size_t size, const char *fmt, va_list args);
>>> int scnprintf(char * buf, size_t size, const char * fmt, ...);
>>> +int scnprintf_pad(char * buf, size_t size, const char * fmt, ...);
>>> 
>>> #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>>> 
>>> diff --git a/tools/lib/vsprintf.c b/tools/lib/vsprintf.c
>>> index e08ee147eab4..149a15013b23 100644
>>> --- a/tools/lib/vsprintf.c
>>> +++ b/tools/lib/vsprintf.c
>>> @@ -23,3 +23,22 @@ int scnprintf(char * buf, size_t size, const char * fmt, ...)
>>> 
>>>       return (i >= ssize) ? (ssize - 1) : i;
>>> }
>>> +
>>> +int scnprintf_pad(char * buf, size_t size, const char * fmt, ...)
>>> +{
>>> +	ssize_t ssize = size;
>>> +	va_list args;
>>> +	int i;
>> 
>> nit: I guess we can avoid mixing int, ssize_t and size_t here?
> 
> I copied that from scnprintf ;-)
> 
> the thing is that at the end we call vsnprintf, which takes size_t
> as size param and returns int, so there will be casting at some
> point in any case..
> 
> I guess the ssize_t was introduced to compare the size_t value with int
> 

Interesting. Given scnprintf works fine, I think we can keep the patch
as-is. 

Thanks,
Song