Re: [PATCH 05/19] perf ftrace: add option '-l/--list-functions' to list available functions

From: Arnaldo Carvalho de Melo
Date: Wed May 20 2020 - 16:59:48 EST


Em Sun, May 10, 2020 at 11:06:14PM +0800, Changbin Du escreveu:
> This adds an option '-l/--list-functions' to list all available functions
> which is read from tracing file 'available_filter_functions'.

Here, in 'perf probe' we have:

[acme@five perf]$ perf probe -F tcp_* | head
tcp_abort
tcp_ack
tcp_ack_update_rtt.isra.0
tcp_add_backlog
tcp_add_reno_sack
tcp_adjust_pcount
tcp_alloc_md5sig_pool
tcp_any_retrans_done.part.0
tcp_assign_congestion_control
tcp_bpf_clone
[acme@five perf]$ perf probe -h -F

Usage: perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]
or: perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]
or: perf probe [<options>] --del '[GROUP:]EVENT' ...
or: perf probe --list [GROUP:]EVENT ...
or: perf probe [<options>] --line 'LINEDESC'
or: perf probe [<options>] --vars 'PROBEPOINT'
or: perf probe [<options>] --funcs

-F, --funcs <[FILTER]>
Show potential probe-able functions.

[acme@five perf]$

So I think we should align with this.

- Arnaldo

> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
> ---
> tools/perf/builtin-ftrace.c | 43 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 1d30c2d5f88b..8133d910d5d8 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -33,6 +33,7 @@ struct perf_ftrace {
> struct evlist *evlist;
> struct target target;
> const char *tracer;
> + bool list_avail_functions;
> struct list_head filters;
> struct list_head notrace;
> struct list_head graph_funcs;
> @@ -142,6 +143,43 @@ static int write_tracing_option_file(const char *name, const char *val)
> return ret;
> }
>
> +static int read_tracing_file_to_stdout(const char *name)
> +{
> + char buf[4096];
> + char *file;
> + int fd;
> + int ret = -1;
> +
> + file = get_tracing_file(name);
> + if (!file) {
> + pr_debug("cannot get tracing file: %s\n", name);
> + return -1;
> + }
> +
> + fd = open(file, O_RDONLY);
> + if (fd < 0) {
> + pr_debug("cannot open tracing file: %s: %s\n",
> + name, str_error_r(errno, buf, sizeof(buf)));
> + goto out;
> + }
> +
> + /* read contents to stdout */
> + while (true) {
> + int n = read(fd, buf, sizeof(buf));
> + if (n <= 0)
> + goto out_close;
> + if (fwrite(buf, n, 1, stdout) != 1)
> + goto out_close;
> + }
> + ret = 0;
> +
> +out_close:
> + close(fd);
> +out:
> + put_tracing_file(file);
> + return ret;
> +}
> +
> static int reset_tracing_cpu(void);
> static void reset_tracing_filters(void);
>
> @@ -332,6 +370,9 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
> signal(SIGCHLD, sig_handler);
> signal(SIGPIPE, sig_handler);
>
> + if (ftrace->list_avail_functions)
> + return read_tracing_file_to_stdout("available_filter_functions");
> +
> if (reset_tracing_files(ftrace) < 0) {
> pr_err("failed to reset ftrace\n");
> goto out;
> @@ -483,6 +524,8 @@ int cmd_ftrace(int argc, const char **argv)
> NULL
> };
> const struct option ftrace_options[] = {
> + OPT_BOOLEAN('L', "list-functions", &ftrace.list_avail_functions,
> + "List available functions to filter"),
> OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
> "trace on existing process id"),
> OPT_INCR('v', "verbose", &verbose,
> --
> 2.25.1
>

--

- Arnaldo