linux-kernel - Re: perf probe -d failing to delete probes

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Date:   Mon, 2 Dec 2019 16:04:52 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: perf probe -d failing to delete probes

Em Mon, Dec 02, 2019 at 03:59:58PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Nov 29, 2019 at 12:13:24PM -0300, Arnaldo Carvalho de Melo escreveu:
> > 
> > Hi Masami,
> > 
> >    Can you please take a look at this?
> > 
> > [root@...co perf]# perf probe -l
> >   probe_perf:map__map_ip (on ui__warn_map_erange+222@...f/tools/perf/builtin-top.c in /home/acme/bin/perf)
> >   probe_perf:map__map_ip (on ui__warn_map_erange+222@...f/tools/perf/builtin-top.c in /home/acme/bin/perf)
> >   probe_perf:map__map_ip (on perf_evlist__set_paused+222@...l/evlist.c in /home/acme/bin/perf)
> >   probe_perf:map__map_ip (on perf_evlist__resume+222@...l/evlist.c in /home/acme/bin/perf)
> >   probe_perf:map__map_ip (on perf_evsel__group_desc+222@...l/evsel.c in /home/acme/bin/perf)
> >   probe_perf:map__map_ip (on svg_partial_wakeline+222@...l/svghelper.c in /home/acme/bin/perf)
> > [root@...co perf]# perf probe -d probe_perf:map_*
> > "probe_perf:map_*" does not hit any event.
> >   Error: Failed to delete events.
> > [root@...co perf]# perf probe -d probe_perf:*
> > "probe_perf:*" does not hit any event.
> >   Error: Failed to delete events.
> > [root@...co perf]# perf probe -d probe*:*
> > "probe*:*" does not hit any event.
> >   Error: Failed to delete events.
> > [root@...co perf]# perf probe -d '*:*'
> > "*:*" does not hit any event.
> >   Error: Failed to delete events.
> > [root@...co perf]#
> 
> [root@...co ~]# perf probe -l
>   probe_perf:map__map_ip (on process_sample_event+6663@...ls/perf/builtin-script.c in /home/acme/bin/perf)
>   probe_perf:map__map_ip (on process_sample_event+6739@...ls/perf/builtin-script.c in /home/acme/bin/perf)
>   probe_perf:map__map_ip (on unwind_entry+436@...l/machine.c in /home/acme/bin/perf)
>   probe_perf:map__map_ip (on machine__process_extra_kernel_map+31@...l/machine.c in /home/acme/bin/perf)
>   probe_perf:map__map_ip (on __maps__insert+192@...l/map.c in /home/acme/bin/perf)
>   probe_perf:map__map_ip (on dso__process_kernel_symbol+336@...l/symbol-elf.c in /home/acme/bin/perf)
> [root@...co ~]# ls -la /sys/kernel/debug/tracing/events/probe_perf/
> total 0
> drwxr-xr-x.   3 root root 0 Nov 29 12:09 .
> drwxr-xr-x. 113 root root 0 Dec  2 15:56 ..
> -rw-r--r--.   1 root root 0 Nov 29 12:09 enable
> -rw-r--r--.   1 root root 0 Nov 29 12:09 filter
> drwxr-xr-x.   2 root root 0 Nov 29 12:09 map__map_ip
> [root@...co ~]#
> 
> Trying to figure out how to remove it via debugfs/tracefs

[root@...co ~]# cat /sys/kernel/debug/tracing/dynamic_events
p:probe_perf/map__map_ip /home/acme/bin/perf:0x000000000005f257
p:probe_perf/map__map_ip /home/acme/bin/perf:0x000000000005f2a3
p:probe_perf/map__map_ip /home/acme/bin/perf:0x00000000000fda24
p:probe_perf/map__map_ip /home/acme/bin/perf:0x00000000000fdacf
p:probe_perf/map__map_ip /home/acme/bin/perf:0x00000000001028d0
p:probe_perf/map__map_ip /home/acme/bin/perf:0x000000000016dd90
[root@...co ~]#

[root@...co ~]# cat /sys/kernel/debug/tracing/kprobe_events
[root@...co ~]#

[root@...co ~]# echo > /sys/kernel/debug/tracing/kprobe_events
[root@...co ~]# perf probe -l
  probe_perf:map__map_ip (on process_sample_event+6663@...ls/perf/builtin-script.c in /home/acme/bin/perf)
  probe_perf:map__map_ip (on process_sample_event+6739@...ls/perf/builtin-script.c in /home/acme/bin/perf)
  probe_perf:map__map_ip (on unwind_entry+436@...l/machine.c in /home/acme/bin/perf)
  probe_perf:map__map_ip (on machine__process_extra_kernel_map+31@...l/machine.c in /home/acme/bin/perf)
  probe_perf:map__map_ip (on __maps__insert+192@...l/map.c in /home/acme/bin/perf)
  probe_perf:map__map_ip (on dso__process_kernel_symbol+336@...l/symbol-elf.c in /home/acme/bin/perf)
[root@...co ~]#

Finally it works:

[root@...co ~]# echo > /sys/kernel/debug/tracing/dynamic_events
[root@...co ~]# cat /sys/kernel/debug/tracing/dynamic_events
[root@...co ~]#
[root@...co ~]# perf probe -l
[root@...co ~]#

A workaround, now to find out why 'perf probe -d '*:*' and the other
reported variants are failing...

- Arnaldo