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Date:   Tue, 31 Aug 2021 16:54:44 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Riccardo Mancini <rickyman7@gmail.com>
Cc:     Ian Rogers <irogers@google.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Jiri Olsa <jolsa@redhat.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org
Subject: Re: [RFC PATCH v1 25/37] perf evsel: move event open in
 evsel__open_cpu to separate function
Message-ID: <YS6JBBW3d4pmcy/U@kernel.org>
References: <cover.1629490974.git.rickyman7@gmail.com>
 <74ac2eea14f45b2cbecffb509dd5f3cd523d4a9b.1629490974.git.rickyman7@gmail.com>
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Em Sat, Aug 21, 2021 at 11:19:31AM +0200, Riccardo Mancini escreveu:
> This is the final patch splitting evsel__open_cpu.
> This patch moves the entire loop code to a separate function, to be
> reused for the multithreaded code.

Are you going to use that 'enum perf_event_open_err' somewhere else?
I.e. is there a need to expose it in evsel.h?

I'm stopping at this patch to give the ones I merged so far some
testing, will now push it to tmp.perf/core.

- Arnaldo
 
> Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
> ---
>  tools/perf/util/evsel.c | 142 ++++++++++++++++++++++++----------------
>  tools/perf/util/evsel.h |  12 ++++
>  2 files changed, 99 insertions(+), 55 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 2e95416b8320c6b9..e41f55a7a70ea630 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1945,6 +1945,82 @@ bool evsel__increase_rlimit(enum rlimit_action *set_rlimit)
>  	return false;
>  }
>  
> +static struct perf_event_open_result perf_event_open(struct evsel *evsel,
> +					pid_t pid, int cpu, int thread,
> +					struct perf_cpu_map *cpus,
> +					struct perf_thread_map *threads)
> +{
> +	int fd, group_fd, rc;
> +	struct perf_event_open_result res;
> +
> +	if (!evsel->cgrp && !evsel->core.system_wide)
> +		pid = perf_thread_map__pid(threads, thread);
> +
> +	group_fd = get_group_fd(evsel, cpu, thread);
> +
> +	test_attr__ready();
> +
> +	pr_debug2_peo("sys_perf_event_open: pid %d  cpu %d  group_fd %d  flags %#lx",
> +			pid, cpus->map[cpu], group_fd, evsel->open_flags);
> +
> +	fd = sys_perf_event_open(&evsel->core.attr, pid, cpus->map[cpu],
> +				group_fd, evsel->open_flags);
> +
> +	FD(evsel, cpu, thread) = fd;
> +	res.fd = fd;
> +
> +	if (fd < 0) {
> +		rc = -errno;
> +
> +		pr_debug2_peo("\nsys_perf_event_open failed, error %d\n",
> +				rc);
> +		res.rc = rc;
> +		res.err = PEO_FALLBACK;
> +		return res;
> +	}
> +
> +	bpf_counter__install_pe(evsel, cpu, fd);
> +
> +	if (unlikely(test_attr__enabled)) {
> +		test_attr__open(&evsel->core.attr, pid,
> +			cpus->map[cpu], fd,
> +			group_fd, evsel->open_flags);
> +	}
> +
> +	pr_debug2_peo(" = %d\n", fd);
> +
> +	if (evsel->bpf_fd >= 0) {
> +		int evt_fd = fd;
> +		int bpf_fd = evsel->bpf_fd;
> +
> +		rc = ioctl(evt_fd,
> +				PERF_EVENT_IOC_SET_BPF,
> +				bpf_fd);
> +		if (rc && errno != EEXIST) {
> +			pr_err("failed to attach bpf fd %d: %s\n",
> +				bpf_fd, strerror(errno));
> +			res.rc = -EINVAL;
> +			res.err = PEO_ERROR;
> +			return res;
> +		}
> +	}
> +
> +	/*
> +	 * If we succeeded but had to kill clockid, fail and
> +	 * have evsel__open_strerror() print us a nice error.
> +	 */
> +	if (perf_missing_features.clockid ||
> +		perf_missing_features.clockid_wrong) {
> +		res.rc = -EINVAL;
> +		res.err = PEO_ERROR;
> +		return res;
> +	}
> +
> +	res.rc = 0;
> +	res.err = PEO_SUCCESS;
> +	return res;
> +}
> +
>  static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
>  		struct perf_thread_map *threads,
>  		int start_cpu, int end_cpu)
> @@ -1952,6 +2028,7 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
>  	int cpu, thread, nthreads;
>  	int pid = -1, err, old_errno;
>  	enum rlimit_action set_rlimit = NO_CHANGE;
> +	struct perf_event_open_result peo_res;
>  
>  	err = __evsel__prepare_open(evsel, cpus, threads);
>  	if (err)
> @@ -1979,67 +2056,22 @@ static int evsel__open_cpu(struct evsel *evsel, struct perf_cpu_map *cpus,
>  	for (cpu = start_cpu; cpu < end_cpu; cpu++) {
>  
>  		for (thread = 0; thread < nthreads; thread++) {
> -			int fd, group_fd;
>  retry_open:
>  			if (thread >= nthreads)
>  				break;
>  
> -			if (!evsel->cgrp && !evsel->core.system_wide)
> -				pid = perf_thread_map__pid(threads, thread);
> -
> -			group_fd = get_group_fd(evsel, cpu, thread);
> -
> -			test_attr__ready();
> -
> -			pr_debug2_peo("sys_perf_event_open: pid %d  cpu %d  group_fd %d  flags %#lx",
> -				pid, cpus->map[cpu], group_fd, evsel->open_flags);
> +			peo_res = perf_event_open(evsel, pid, cpu, thread, cpus,
> +						threads);
>  
> -			fd = sys_perf_event_open(&evsel->core.attr, pid, cpus->map[cpu],
> -						group_fd, evsel->open_flags);
> -
> -			FD(evsel, cpu, thread) = fd;
> -
> -			if (fd < 0) {
> -				err = -errno;
> -
> -				pr_debug2_peo("\nsys_perf_event_open failed, error %d\n",
> -					  err);
> +			err = peo_res.rc;
> +			switch (peo_res.err) {
> +			case PEO_SUCCESS:
> +				set_rlimit = NO_CHANGE;
> +				continue;
> +			case PEO_FALLBACK:
>  				goto try_fallback;
> -			}
> -
> -			bpf_counter__install_pe(evsel, cpu, fd);
> -
> -			if (unlikely(test_attr__enabled)) {
> -				test_attr__open(&evsel->core.attr, pid, cpus->map[cpu],
> -						fd, group_fd, evsel->open_flags);
> -			}
> -
> -			pr_debug2_peo(" = %d\n", fd);
> -
> -			if (evsel->bpf_fd >= 0) {
> -				int evt_fd = fd;
> -				int bpf_fd = evsel->bpf_fd;
> -
> -				err = ioctl(evt_fd,
> -					    PERF_EVENT_IOC_SET_BPF,
> -					    bpf_fd);
> -				if (err && errno != EEXIST) {
> -					pr_err("failed to attach bpf fd %d: %s\n",
> -					       bpf_fd, strerror(errno));
> -					err = -EINVAL;
> -					goto out_close;
> -				}
> -			}
> -
> -			set_rlimit = NO_CHANGE;
> -
> -			/*
> -			 * If we succeeded but had to kill clockid, fail and
> -			 * have evsel__open_strerror() print us a nice error.
> -			 */
> -			if (perf_missing_features.clockid ||
> -			    perf_missing_features.clockid_wrong) {
> -				err = -EINVAL;
> +			default:
> +			case PEO_ERROR:
>  				goto out_close;
>  			}
>  		}
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index 0a245afab2d87d74..8c9827a93ac001a7 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -282,6 +282,18 @@ int evsel__enable(struct evsel *evsel);
>  int evsel__disable(struct evsel *evsel);
>  int evsel__disable_cpu(struct evsel *evsel, int cpu);
>  
> +enum perf_event_open_err {
> +	PEO_SUCCESS,
> +	PEO_FALLBACK,
> +	PEO_ERROR
> +};
> +
> +struct perf_event_open_result {
> +	enum perf_event_open_err err;
> +	int rc;
> +	int fd;
> +};
> +
>  int evsel__open_per_cpu(struct evsel *evsel, struct perf_cpu_map *cpus, int cpu);
>  int evsel__open_per_thread(struct evsel *evsel, struct perf_thread_map *threads);
>  int evsel__open(struct evsel *evsel, struct perf_cpu_map *cpus,
> -- 
> 2.31.1

-- 

- Arnaldo