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

From: Changbin Du
Date: Sat Jun 06 2020 - 10:43:07 EST


On Wed, May 20, 2020 at 05:59:40PM -0300, Arnaldo Carvalho de Melo wrote:
> 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
>
Agreed. Will do that in next revision.

> > 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

--
Cheers,
Changbin Du