linux-kernel - Re: [PATCH v3 01/10] perf/cgroup: Reorder perf_cgroup

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Date:   Thu, 14 Nov 2019 09:50:11 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Kees Cook <keescook@...omium.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Petr Mladek <pmladek@...e.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Qian Cai <cai@....pw>, Joe Lawrence <joe.lawrence@...hat.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Sri Krishna chowdary <schowdary@...dia.com>,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Changbin Du <changbin.du@...el.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Gary Hook <Gary.Hook@....com>, Arnd Bergmann <arnd@...db.de>,
        Kan Liang <kan.liang@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v3 01/10] perf/cgroup: Reorder perf_cgroup_connect()


Hurm, you didn't fix my missing Changelog.. 

On Wed, Nov 13, 2019 at 04:30:33PM -0800, Ian Rogers wrote:
> From: Peter Zijlstra <peterz@...radead.org>

Move perf_cgroup_connect() after perf_event_alloc(), such that we can
find/use the PMU's cpu context.

> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
>  kernel/events/core.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index cfd89b4a02d8..0dce28b0aae0 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -10597,12 +10597,6 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
>  	if (!has_branch_stack(event))
>  		event->attr.branch_sample_type = 0;
>  
> -	if (cgroup_fd != -1) {
> -		err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
> -		if (err)
> -			goto err_ns;
> -	}
> -
>  	pmu = perf_init_event(event);
>  	if (IS_ERR(pmu)) {
>  		err = PTR_ERR(pmu);
> @@ -10615,6 +10609,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
>  		goto err_pmu;
>  	}
>  
> +	if (cgroup_fd != -1) {
> +		err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
> +		if (err)
> +			goto err_pmu;
> +	}
> +
>  	err = exclusive_event_init(event);
>  	if (err)
>  		goto err_pmu;
> @@ -10675,12 +10675,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
>  	exclusive_event_destroy(event);
>  
>  err_pmu:
> +	if (is_cgroup_event(event))
> +		perf_detach_cgroup(event);
>  	if (event->destroy)
>  		event->destroy(event);
>  	module_put(pmu->module);
>  err_ns:
> -	if (is_cgroup_event(event))
> -		perf_detach_cgroup(event);
>  	if (event->ns)
>  		put_pid_ns(event->ns);
>  	if (event->hw.target)
> -- 
> 2.24.0.432.g9d3f5f5b63-goog
>