linux-kernel - Re: [PATCH v2] perf test: Fix false TEST

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Date:	Tue, 15 Dec 2015 18:03:21 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	acme@...nel.org, jolsa@...nel.org, adrian.hunter@...el.com,
	a.p.zijlstra@...llo.nl, masami.hiramatsu.pt@...achi.com,
	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH v2] perf test: Fix false TEST_OK result for 'perf test
 hist'

On Tue, Dec 15, 2015 at 08:09:26AM +0000, Wang Nan wrote:
> Commit 71d6de64feddd4b455555326fba2111b3006d9e0 ('perf test: Fix hist
> testcases when kptr_restrict is on') solves a double free problem when
> 'perf test hist' calling setup_fake_machine(). However, the result is
> still incorrect. For example:
> 
>  $ ./perf test -v 'filtering hist entries'
>  25: Test filtering hist entries                              :
>  --- start ---
>  test child forked, pid 4186
>  Cannot create kernel maps
>  test child finished with 0
>  ---- end ----
>  Test filtering hist entries: Ok
> 
> In this case the body of this test is not get executed at all, but the
> result is 'Ok'.
> 
> Actually, in setup_fake_machine() there's no need to create real kernel
> maps. What we want is the fake maps. This patch removes the
> machine__create_kernel_maps() in setup_fake_machine(), so it won't be
> affected by kptr_restrict setting.
> 
> Test result:
> 
>  $ cat /proc/sys/kernel/kptr_restrict
>  1
>  $ ~/perf test -v hist
>  15: Test matching and linking multiple hists                 :
>  --- start ---
>  test child forked, pid 24031
>  test child finished with 0
>  ---- end ----
>  Test matching and linking multiple hists: Ok
>  [SNIP]
> 
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Suggested-by: Namhyung Kim <namhyung@...nel.org>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung


> ---
>  tools/perf/tests/hists_common.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
> index bcfd081..071a8b5 100644
> --- a/tools/perf/tests/hists_common.c
> +++ b/tools/perf/tests/hists_common.c
> @@ -87,11 +87,6 @@ struct machine *setup_fake_machine(struct machines *machines)
>  		return NULL;
>  	}
>  
> -	if (machine__create_kernel_maps(machine)) {
> -		pr_debug("Cannot create kernel maps\n");
> -		return NULL;
> -	}
> -
>  	for (i = 0; i < ARRAY_SIZE(fake_threads); i++) {
>  		struct thread *thread;
>  
> -- 
> 1.8.3.4
> 
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