linux-kernel - Re: [PATCH v2 1/5] perf probe: Split add_perf_probe

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Message-ID: <55EBEF99.8010506@huawei.com>
Date:	Sun, 6 Sep 2015 15:47:37 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	<pi3orama@....com>
Subject: Re: [PATCH v2 1/5] perf probe: Split add_perf_probe_events()

Hi Namhyung,

Thanks for this patchset.

Could you plase have a look at patch 5/27 and 6/27 in my newest pull 
request?
These 2 patches utilize new probing API to create probe point and collect
probe_trace_events. I'm not very sure I fully understand your design 
principle,
especially the cleanup part, because I can see different functions 
dealing with
cleanup:

cleanup_perf_probe_events
del_perf_probe_events
clear_perf_probe_event
clear_probe_trace_event

But non of them works perfectly for me.

In bpf_prog_priv__clear() function of 6/27, I copied some code from
cleanup_perf_probe_events(), because I think when destroying bpf programs,
the probe_trace_events should also be cleanuped, but we don't need call
exit_symbol_maps() many times, because we are in 'perf record', and not
sure whether other parts of perf need symbol maps. Otherwise I think 
directly
calling cleanup_perf_probe_events() sould be better.

You can find patch from:

http://lkml.kernel.org/n/1441523623-152703-6-git-send-email-wangnan0@huawei.com

http://lkml.kernel.org/n/1441523623-152703-7-git-send-email-wangnan0@huawei.com

Thank you.

On 2015/9/4 20:15, Namhyung Kim wrote:
> The add_perf_probe_events() does 3 things:
>
>   1. convert all perf events to trace events
>   2. add all trace events to kernel
>   3. cleanup all trace events
>
> But sometimes we need to do something with the trace events.  So split
> the funtion into three, so that it can access intermediate trace events
> via struct __event_package if needed.
>
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>   tools/perf/util/probe-event.c | 39 +++++++++++++++++++++++++++++++++++----
>   1 file changed, 35 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index eb5f18b75402..2c762f41e7a5 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -2765,9 +2765,10 @@ struct __event_package {
>   	int				ntevs;
>   };
>   
> -int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
> +static int convert_perf_probe_events(struct perf_probe_event *pevs, int npevs,
> +				     struct __event_package **ppkgs)
>   {
> -	int i, j, ret;
> +	int i, ret;
>   	struct __event_package *pkgs;
>   
>   	ret = 0;
> @@ -2792,12 +2793,21 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
>   		ret  = convert_to_probe_trace_events(pkgs[i].pev,
>   						     &pkgs[i].tevs);
>   		if (ret < 0)
> -			goto end;
> +			return ret;
>   		pkgs[i].ntevs = ret;
>   	}
>   	/* This just release blacklist only if allocated */
>   	kprobe_blacklist__release();
>   
> +	*ppkgs = pkgs;
> +
> +	return 0;
> +}
> +
> +static int apply_perf_probe_events(struct __event_package *pkgs, int npevs)
> +{
> +	int i, ret = 0;
> +
>   	/* Loop 2: add all events */
>   	for (i = 0; i < npevs; i++) {
>   		ret = __add_probe_trace_events(pkgs[i].pev, pkgs[i].tevs,
> @@ -2806,7 +2816,16 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
>   		if (ret < 0)
>   			break;
>   	}
> -end:
> +	return ret;
> +}
> +
> +static void cleanup_perf_probe_events(struct __event_package *pkgs, int npevs)
> +{
> +	int i, j;
> +
> +	if (pkgs == NULL)
> +		return;
> +
>   	/* Loop 3: cleanup and free trace events  */
>   	for (i = 0; i < npevs; i++) {
>   		for (j = 0; j < pkgs[i].ntevs; j++)
> @@ -2815,6 +2834,18 @@ end:
>   	}
>   	free(pkgs);
>   	exit_symbol_maps();
> +}
> +
> +int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
> +{
> +	int ret;
> +	struct __event_package *pkgs = NULL;
> +
> +	ret = convert_perf_probe_events(pevs, npevs, &pkgs);
> +	if (ret == 0)
> +		ret = apply_perf_probe_events(pkgs, npevs);
> +
> +	cleanup_perf_probe_events(pkgs, npevs);
>   
>   	return ret;
>   }


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