linux-kernel - Re: [PATCH 01/35] perf tools: Fix dso

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Message-ID: <YtV0vXJLbfTywZ1B@kernel.org>
Date:   Mon, 18 Jul 2022 11:57:01 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH 01/35] perf tools: Fix dso_id inode generation comparison

Em Mon, Jul 11, 2022 at 12:31:44PM +0300, Adrian Hunter escreveu:
> Synthesized MMAP events have zero ino_generation, so do not compare zero
> values.
> 
> Fixes: 0e3149f86b99 ("perf dso: Move dso_id from 'struct map' to 'struct dso'")
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/util/dsos.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/dsos.c b/tools/perf/util/dsos.c
> index b97366f77bbf..839a1f384733 100644
> --- a/tools/perf/util/dsos.c
> +++ b/tools/perf/util/dsos.c
> @@ -23,8 +23,14 @@ static int __dso_id__cmp(struct dso_id *a, struct dso_id *b)
>  	if (a->ino > b->ino) return -1;
>  	if (a->ino < b->ino) return 1;
>  
> -	if (a->ino_generation > b->ino_generation) return -1;
> -	if (a->ino_generation < b->ino_generation) return 1;
> +	/*
> +	 * Synthesized MMAP events have zero ino_generation, so do not compare
> +	 * zero values.
> +	 */
> +	if (a->ino_generation && b->ino_generation) {
> +		if (a->ino_generation > b->ino_generation) return -1;
> +		if (a->ino_generation < b->ino_generation) return 1;
> +	}

But comparing didn't harm right? when its !0 now we may have three
comparisions instead of 2 :-\

The comment has some value tho, so I'm merging this :-)

- Arnaldo