From: Namhyung Kim <namhyung@kernel.org>

Date: Sun, 18 Jun 2017 23:23:00 +0900

Subject: perf ftrace: Move setup_pager before opening trace_pipe

Git-commit: 29681bc5bb4326c2f9eac5dc68d8fad3e88b4bb5

Patch-mainline: v4.13-rc1

References: bsc#1070010 (git-fixes)

Signed-off-By: Tony Jones <tonyj@suse.de>

​

The 'perf ftrace' command fails to reset tracer after finishing

recording like below:

​

  $ sudo perf ftrace -v hello

  write 'nop' to tracing/current_tracer failed: Device or resource busy

  ...

​

This is because the trace_pipe file is open in pager process.  Move the

pager setup to before opening the file.

​

Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Cc: Frederic Weisbecker <fweisbec@gmail.com>

Cc: Jiri Olsa <jolsa@kernel.org>

Cc: Masami Hiramatsu <mhiramat@kernel.org>

Cc: Peter Zijlstra <peterz@infradead.org>

Cc: Steven Rostedt <rostedt@goodmis.org>

Cc: kernel-team@lge.com

Fixes: 583359646fde ("perf ftrace: Use pager for displaying result")

Link: http://lkml.kernel.org/r/20170618142302.25390-2-namhyung@kernel.org

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

---

 tools/perf/builtin-ftrace.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

​

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c

index 966a94fa8200..982b98ee639e 100644

--- a/tools/perf/builtin-ftrace.c

+++ b/tools/perf/builtin-ftrace.c

@@ -231,6 +231,8 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)

        goto out_reset;

    }

+   setup_pager();

+

    trace_file = get_tracing_file("trace_pipe");

    if (!trace_file) {

        pr_err("failed to open trace_pipe\n");

@@ -254,8 +256,6 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)

        goto out_close_fd;

    }

-   setup_pager();

-

    perf_evlist__start_workload(ftrace->evlist);

    while (!done) {

​

​