linux-kernel - Re: [BUG] perf probe can't remove probes

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Date:   Thu, 26 Nov 2020 14:26:03 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Clark Williams <williams@...hat.com>,
        linux-perf-users@...r.kernel.org
Subject: Re: [BUG] perf probe can't remove probes

Em Thu, Nov 26, 2020 at 09:21:25AM +0900, Masami Hiramatsu escreveu:
> Hi Arnaldo,
> 
> On Wed, 25 Nov 2020 14:27:55 -0300
> Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
> 
> > 
> > Masami, have you stumbled on this already?
> > 
> > [root@...enth ~]# perf probe security_locked_down%return 'ret=$retval'
> > Added new event:
> >   probe:security_locked_down__return (on security_locked_down%return with ret=$retval)
> > 
> > You can now use it in all perf tools, such as:
> > 
> > 	perf record -e probe:security_locked_down__return -aR sleep 1
> > 
> > [root@...enth ~]# perf probe security_locked_down what
> > Added new event:
> >   probe:security_locked_down (on security_locked_down with what)
> > 
> > You can now use it in all perf tools, such as:
> > 
> > 	perf record -e probe:security_locked_down -aR sleep 1
> > 
> > [root@...enth ~]#
> > 
> > 
> > [root@...enth ~]# uname -r
> > 5.10.0-rc3.bpfsign+
> > [root@...enth ~]# perf probe -l
> >   probe:security_locked_down (on security_locked_down@.../bpf/security/security.c with what)
> >   probe:security_locked_down__return (on security_locked_down%return@.../bpf/security/security.c with ret)
> > [root@...enth ~]# perf probe -D '*:*'
> > Semantic error :There is non-digit char in line number.
> > 
> >  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
> > 
> >     -D, --definition <[EVENT=]FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT [[NAME=]ARG ...]>
> >                           Show trace event definition of given traceevent for k/uprobe_events.
> 
> As you can see, "-D" is showing definition. Not delete. (*)
> Delete is "-d" or "--del".

Yeah, I was in a hurry and looked at just the first line right after the
command, didn't want to forget reporting it so sent the "bug" report,
d0h, sorry about the noise, using -d or --del works.

But having both -d and -D, in retrospect, wasn't such a good idea :-\

- Arnaldo
 
> (*) this option is for different version of kernel, remote-machine
> and boot-time tracing.
> 
> > [root@...enth ~]# perf probe probe:security_locked_down
> > Semantic error :There is non-digit char in line number.
> >   Error: Command Parse Error.
> > [root@...enth ~]# perf probe probe:security_locked_down__return
> > Semantic error :There is non-digit char in line number.
> >   Error: Command Parse Error.
> 
> Since you don't pass any option, both are for adding new probe event.
> 
> What happen if you run
> 
> $ perf probe -d "*:*"
> 
> ?
> 
> Thank you,
> 
> -- 
> Masami Hiramatsu <mhiramat@...nel.org>

-- 

- Arnaldo