linux-kernel - Re: [PATCH 1/4] perf cgroup: Avoid needless closing of unopened fd

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Date:   Mon, 20 Apr 2020 10:48:47 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Tommi Rantala <tommi.t.rantala@...ia.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] perf cgroup: Avoid needless closing of unopened fd

On Fri, Apr 17, 2020 at 04:23:26PM +0300, Tommi Rantala wrote:
> Do not bother with close() if fd is not valid, just to silence valgrind:
> 
>     $ valgrind ./perf script
>     ==59169== Memcheck, a memory error detector
>     ==59169== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
>     ==59169== Using Valgrind-3.14.0 and LibVEX; rerun with -h for copyright info
>     ==59169== Command: ./perf script
>     ==59169==
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
>     ==59169== Warning: invalid file descriptor -1 in syscall close()
> 
> Signed-off-by: Tommi Rantala <tommi.t.rantala@...ia.com>

Acked-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka

> ---
>  tools/perf/util/cgroup.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
> index b73fb7823048..050dea9f1e88 100644
> --- a/tools/perf/util/cgroup.c
> +++ b/tools/perf/util/cgroup.c
> @@ -107,7 +107,8 @@ static int add_cgroup(struct evlist *evlist, const char *str)
>  
>  static void cgroup__delete(struct cgroup *cgroup)
>  {
> -	close(cgroup->fd);
> +	if (cgroup->fd >= 0)
> +		close(cgroup->fd);
>  	zfree(&cgroup->name);
>  	free(cgroup);
>  }
> -- 
> 2.25.2
>