Messages in this thread |  | | From | Namhyung Kim <> | Date | Mon, 13 Jul 2020 10:49:40 +0900 | Subject | Re: [PATCH v5 02/17] perf ftrace: add option '-F/--funcs' to list available functions |
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Hello,
On Sat, Jul 11, 2020 at 9:42 PM Changbin Du <changbin.du@gmail.com> wrote: > > This adds an option '-F/--funcs' to list all available functions to trace, > which is read from tracing file 'available_filter_functions'. > > $ sudo ./perf ftrace -F | head > trace_initcall_finish_cb > initcall_blacklisted > do_one_initcall > do_one_initcall > trace_initcall_start_cb > run_init_process > try_to_run_init_process > match_dev_by_label > match_dev_by_uuid > rootfs_init_fs_context > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > --- > v2: option name '-l/--list-functions' -> '-F/--funcs' > --- > tools/perf/Documentation/perf-ftrace.txt | 4 +++ > tools/perf/builtin-ftrace.c | 43 ++++++++++++++++++++++++ > 2 files changed, 47 insertions(+) > > diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt > index 952e46669168..d79560dea19f 100644 > --- a/tools/perf/Documentation/perf-ftrace.txt > +++ b/tools/perf/Documentation/perf-ftrace.txt > @@ -30,6 +30,10 @@ OPTIONS > --verbose=:: > Verbosity level. > > +-F:: > +--funcs:: > + List all available functions to trace. > + > -p:: > --pid=:: > Trace on existing process id (comma separated list). > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > index 5f53da87040d..244cc8e6bd60 100644 > --- a/tools/perf/builtin-ftrace.c > +++ b/tools/perf/builtin-ftrace.c > @@ -32,6 +32,7 @@ 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; > @@ -127,6 +128,43 @@ static int append_tracing_file(const char *name, const char *val) > return __write_tracing_file(name, val, true); > } > > +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;
As I said before, there's no break in the loop above so the ret can never be 0.
Thanks Namhyung
> + > +out_close: > + close(fd); > +out: > + put_tracing_file(file); > + return ret; > +} > + > static int reset_tracing_cpu(void); > static void reset_tracing_filters(void); > > @@ -301,6 +339,9 @@ 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; > @@ -470,6 +511,8 @@ int cmd_ftrace(int argc, const char **argv) > const struct option ftrace_options[] = { > OPT_STRING('t', "tracer", &ftrace.tracer, "tracer", > "tracer to use: function or function_graph (This option is deprecated)"), > + OPT_BOOLEAN('F', "funcs", &ftrace.list_avail_functions, > + "Show 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 >
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