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Subject: Re: [PATCH V3 4/6] perf tools: Add FIFO file names as alternative
 options to --control
To:     Adrian Hunter <adrian.hunter@intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>
Cc:     Andi Kleen <ak@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>,
        linux-kernel@vger.kernel.org
References: <20200901200655.GC470123@krava>
 <20200902105707.11491-1-adrian.hunter@intel.com>
From:   Alexey Budankov <alexey.budankov@linux.intel.com>
Organization: Intel Corp.
Message-ID: <97818947-ed04-1b53-c71a-f00732141ca7@linux.intel.com>
Date:   Wed, 2 Sep 2020 20:03:08 +0300
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On 02.09.2020 13:57, Adrian Hunter wrote:
> Enable the --control option to accept file names as an alternative to
> file descriptors.
> 
> Example:
> 
>  $ mkfifo perf.control
>  $ mkfifo perf.ack
>  $ cat perf.ack &
>  [1] 6808
>  $ perf record --control fifo:perf.control,perf.ack -- sleep 300 &
>  [2] 6810
>  $ echo disable > perf.control
>  $ Events disabled
>  ack
> 
>  $ echo enable > perf.control
>  $ Events enabled
>  ack
> 
>  $ echo disable > perf.control
>  $ Events disabled
>  ack
> 
>  $ kill %2
>  [ perf record: Woken up 4 times to write data ]
>  $ [ perf record: Captured and wrote 0.018 MB perf.data (7 samples) ]
> 
>  [1]-  Done                    cat perf.ack
>  [2]+  Terminated              perf record --control fifo:perf.control,perf.ack -- sleep 300
>  $
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> Acked-by: Jiri Olsa <jolsa@redhat.com>
> ---
> 
> 
> Changes in V3:
> 
> 	Rename evlist__parse_control_names to evlist__parse_control_fifo
> 	Explicitly initialize *ctl_fd_close = false
> 
> 
>  tools/perf/Documentation/perf-record.txt |  2 +
>  tools/perf/Documentation/perf-stat.txt   |  2 +
>  tools/perf/builtin-record.c              | 34 +++++++++++----
>  tools/perf/builtin-stat.c                | 18 ++++++--
>  tools/perf/util/evlist.c                 | 55 +++++++++++++++++++++++-
>  tools/perf/util/evlist.h                 |  2 +-
>  tools/perf/util/record.h                 |  1 +
>  tools/perf/util/stat.h                   |  1 +
>  8 files changed, 101 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index 07c4734f1c7a..2ffc1196d2b8 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -627,7 +627,9 @@ option. The -e option and this one can be mixed and matched.  Events
>  can be grouped using the {} notation.
>  endif::HAVE_LIBPFM[]
>  
> +--control=fifo:ctl-fifo[,ack-fifo]::
>  --control=fd:ctl-fd[,ack-fd]::
> +ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
>  Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
>  'disable': disable events). Measurements can be started with events disabled using
>  --delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
> index 7fb7368cc2d9..d33ffd11bb85 100644
> --- a/tools/perf/Documentation/perf-stat.txt
> +++ b/tools/perf/Documentation/perf-stat.txt
> @@ -176,7 +176,9 @@ with it.  --append may be used here.  Examples:
>       3>results  perf stat --log-fd 3          -- $cmd
>       3>>results perf stat --log-fd 3 --append -- $cmd
>  
> +--control=fifo:ctl-fifo[,ack-fifo]::
>  --control=fd:ctl-fd[,ack-fd]::
> +ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows.
>  Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
>  'disable': disable events). Measurements can be started with events disabled using
>  --delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index f2ab5bd7e2ba..117dd180f780 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -2236,7 +2236,17 @@ static int parse_control_option(const struct option *opt,
>  {
>  	struct record_opts *opts = opt->value;
>  
> -	return evlist__parse_control(str, &opts->ctl_fd, &opts->ctl_fd_ack);
> +	return evlist__parse_control(str, &opts->ctl_fd, &opts->ctl_fd_ack, &opts->ctl_fd_close);
> +}
> +
> +static void close_control_option(struct record_opts *opts)

This function above and the same one for stat mode below look duplicating.
It could possibly be combined.

Acked-by: Alexei Budankov <alexey.budankov@linux.intel.com>

Regards,
Alexei

> +{
> +	if (opts->ctl_fd_close) {
> +		opts->ctl_fd_close = false;
> +		close(opts->ctl_fd);
> +		if (opts->ctl_fd_ack >= 0)
> +			close(opts->ctl_fd_ack);
> +	}
>  }
>  
>  static void switch_output_size_warn(struct record *rec)
> @@ -2578,9 +2588,10 @@ static struct option __record_options[] = {
>  		"libpfm4 event selector. use 'perf list' to list available events",
>  		parse_libpfm_events_option),
>  #endif
> -	OPT_CALLBACK(0, "control", &record.opts, "fd:ctl-fd[,ack-fd]",
> +	OPT_CALLBACK(0, "control", &record.opts, "fd:ctl-fd[,ack-fd] or fifo:ctl-fifo[,ack-fifo]",
>  		     "Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, 'disable': disable events).\n"
> -		     "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.",
> +		     "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.\n"
> +		     "\t\t\t  Alternatively, ctl-fifo / ack-fifo will be opened and used as ctl-fd / ack-fd.",
>  		      parse_control_option),
>  	OPT_END()
>  };
> @@ -2653,12 +2664,14 @@ int cmd_record(int argc, const char **argv)
>  	    !perf_can_record_switch_events()) {
>  		ui__error("kernel does not support recording context switch events\n");
>  		parse_options_usage(record_usage, record_options, "switch-events", 0);
> -		return -EINVAL;
> +		err = -EINVAL;
> +		goto out_opts;
>  	}
>  
>  	if (switch_output_setup(rec)) {
>  		parse_options_usage(record_usage, record_options, "switch-output", 0);
> -		return -EINVAL;
> +		err = -EINVAL;
> +		goto out_opts;
>  	}
>  
>  	if (rec->switch_output.time) {
> @@ -2669,8 +2682,10 @@ int cmd_record(int argc, const char **argv)
>  	if (rec->switch_output.num_files) {
>  		rec->switch_output.filenames = calloc(sizeof(char *),
>  						      rec->switch_output.num_files);
> -		if (!rec->switch_output.filenames)
> -			return -EINVAL;
> +		if (!rec->switch_output.filenames) {
> +			err = -EINVAL;
> +			goto out_opts;
> +		}
>  	}
>  
>  	/*
> @@ -2686,7 +2701,8 @@ int cmd_record(int argc, const char **argv)
>  		rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
>  		if (!rec->affinity_mask.bits) {
>  			pr_err("Failed to allocate thread mask for %zd cpus\n", rec->affinity_mask.nbits);
> -			return -ENOMEM;
> +			err = -ENOMEM;
> +			goto out_opts;
>  		}
>  		pr_debug2("thread mask[%zd]: empty\n", rec->affinity_mask.nbits);
>  	}
> @@ -2817,6 +2833,8 @@ int cmd_record(int argc, const char **argv)
>  	evlist__delete(rec->evlist);
>  	symbol__exit();
>  	auxtrace_record__free(rec->itr);
> +out_opts:
> +	close_control_option(&rec->opts);
>  	return err;
>  }
>  
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 12ce5cf2b10e..6170226d44f9 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -1047,7 +1047,17 @@ static int parse_control_option(const struct option *opt,
>  {
>  	struct perf_stat_config *config = opt->value;
>  
> -	return evlist__parse_control(str, &config->ctl_fd, &config->ctl_fd_ack);
> +	return evlist__parse_control(str, &config->ctl_fd, &config->ctl_fd_ack, &config->ctl_fd_close);
> +}
> +
> +static void close_control_option(struct perf_stat_config *config)
> +{
> +	if (config->ctl_fd_close) {
> +		config->ctl_fd_close = false;
> +		close(config->ctl_fd);
> +		if (config->ctl_fd_ack >= 0)
> +			close(config->ctl_fd_ack);
> +	}
>  }
>  
>  static struct option stat_options[] = {
> @@ -1151,9 +1161,10 @@ static struct option stat_options[] = {
>  		"libpfm4 event selector. use 'perf list' to list available events",
>  		parse_libpfm_events_option),
>  #endif
> -	OPT_CALLBACK(0, "control", &stat_config, "fd:ctl-fd[,ack-fd]",
> +	OPT_CALLBACK(0, "control", &stat_config, "fd:ctl-fd[,ack-fd] or fifo:ctl-fifo[,ack-fifo]",
>  		     "Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, 'disable': disable events).\n"
> -		     "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.",
> +		     "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.\n"
> +		     "\t\t\t  Alternatively, ctl-fifo / ack-fifo will be opened and used as ctl-fd / ack-fd.",
>  		      parse_control_option),
>  	OPT_END()
>  };
> @@ -2396,6 +2407,7 @@ int cmd_stat(int argc, const char **argv)
>  
>  	metricgroup__rblist_exit(&stat_config.metric_events);
>  	runtime_stat_delete(&stat_config);
> +	close_control_option(&stat_config);
>  
>  	return status;
>  }
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 47d1045a19af..00593e5f2a9d 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1727,12 +1727,63 @@ struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list,
>  	return leader;
>  }
>  
> -int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack)
> +static int evlist__parse_control_fifo(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close)
> +{
> +	char *s, *p;
> +	int ret = 0, fd;
> +
> +	if (strncmp(str, "fifo:", 5))
> +		return -EINVAL;
> +
> +	str += 5;
> +	if (!*str || *str == ',')
> +		return -EINVAL;
> +
> +	s = strdup(str);
> +	if (!s)
> +		return -ENOMEM;
> +
> +	p = strchr(s, ',');
> +	if (p)
> +		*p = '\0';
> +
> +	/*
> +	 * O_RDWR avoids POLLHUPs which is necessary to allow the other
> +	 * end of a FIFO to be repeatedly opened and closed.
> +	 */
> +	fd = open(s, O_RDWR | O_NONBLOCK | O_CLOEXEC);
> +	if (fd < 0) {
> +		pr_err("Failed to open '%s'\n", s);
> +		ret = -errno;
> +		goto out_free;
> +	}
> +	*ctl_fd = fd;
> +	*ctl_fd_close = true;
> +
> +	if (p && *++p) {
> +		/* O_RDWR | O_NONBLOCK means the other end need not be open */
> +		fd = open(p, O_RDWR | O_NONBLOCK | O_CLOEXEC);
> +		if (fd < 0) {
> +			pr_err("Failed to open '%s'\n", p);
> +			ret = -errno;
> +			goto out_free;
> +		}
> +		*ctl_fd_ack = fd;
> +	}
> +
> +out_free:
> +	free(s);
> +	return ret;
> +}
> +
> +int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close)
>  {
>  	char *comma = NULL, *endptr = NULL;
>  
> +	*ctl_fd_close = false;
> +
>  	if (strncmp(str, "fd:", 3))
> -		return -EINVAL;
> +		return evlist__parse_control_fifo(str, ctl_fd, ctl_fd_ack, ctl_fd_close);
>  
>  	*ctl_fd = strtoul(&str[3], &endptr, 0);
>  	if (endptr == &str[3])
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index a5a5a07d5c55..a5678eb5ee60 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -373,7 +373,7 @@ enum evlist_ctl_cmd {
>  	EVLIST_CTL_CMD_ACK
>  };
>  
> -int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack);
> +int evlist__parse_control(const char *str, int *ctl_fd, int *ctl_fd_ack, bool *ctl_fd_close);
>  int evlist__initialize_ctlfd(struct evlist *evlist, int ctl_fd, int ctl_fd_ack);
>  int evlist__finalize_ctlfd(struct evlist *evlist);
>  bool evlist__ctlfd_initialized(struct evlist *evlist);
> diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
> index 03678ff25539..266760ac9143 100644
> --- a/tools/perf/util/record.h
> +++ b/tools/perf/util/record.h
> @@ -73,6 +73,7 @@ struct record_opts {
>  	unsigned int  nr_threads_synthesize;
>  	int	      ctl_fd;
>  	int	      ctl_fd_ack;
> +	bool	      ctl_fd_close;
>  };
>  
>  extern const char * const *record_usage;
> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
> index f8778cffd941..65402e13b704 100644
> --- a/tools/perf/util/stat.h
> +++ b/tools/perf/util/stat.h
> @@ -135,6 +135,7 @@ struct perf_stat_config {
>  	struct rblist		 metric_events;
>  	int			 ctl_fd;
>  	int			 ctl_fd_ack;
> +	bool			 ctl_fd_close;
>  };
>  
>  void perf_stat__set_big_num(int set);
>