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

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Message-Id: <20201126092125.402257a8776637d6bd2e090c@kernel.org>
Date:   Thu, 26 Nov 2020 09:21:25 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...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

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".

(*) 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>