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From: =?UTF-8?Q?=C5=81ukasz_Bartosik?= <lb@semihalf.com>
Date: Thu, 21 Dec 2023 16:21:49 +0100
Message-ID: <CAK8ByeJHAPijVWbATUxXpXHa7uCn3dwLgi_6ckfWY0ADmBwqcQ@mail.gmail.com>
Subject: Re: [re: PATCH v2 00/15 - 05/11] dyndbg: change +T:name_terminator to dot
To: Petr Mladek <pmladek@suse.com>
Cc: Jim Cromie <jim.cromie@gmail.com>, linux-kernel@vger.kernel.org, 
	akpm@linux-foundation.org, bleung@google.com, contact@emersion.fr, 
	daniel@ffwll.ch, dianders@chromium.org, groeck@google.com, jbaron@akamai.com, 
	john.ogness@linutronix.de, keescook@chromium.org, ppaalanen@gmail.com, 
	rostedt@goodmis.org, seanpaul@chromium.org, sergey.senozhatsky@gmail.com, 
	upstream@semihalf.com, vincent.whitchurch@axis.com, yanivt@google.com, 
	gregkh@linuxfoundation.org
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pon., 18 gru 2023 o 18:29 Petr Mladek <pmladek@suse.com> napisa=C5=82(a):
>
> On Thu 2023-12-07 17:15:08, Jim Cromie wrote:
> > This replaces ',' with '.' as the char that ends the +T:name.
> >
> > This allows a later patch to treat ',' as a space, which mostly
> > eliminates the need to quote query/rules.  And this in turn avoids
> > quoting hassles:
> >
> >   modprobe test_dynamic_debug dyndbg=3Dclass,D2_CORE,+p
> >
> > It is particularly good for passing boot-args into test-scripts.
> >
> >   vng -p 4 -v \
> >   -a test_dynamic_debug.dyndbg=3Dclass,D2_CORE,+p
>
> Could you please add example how it looked before and after?

Before a user had to issue a command in the format
modprobe test_dynamic_debug dyndbg=3D"class D2_CORE +p"

Now a use can use either
modprobe test_dynamic_debug dyndbg=3D"class D2_CORE +p"
or
modprobe test_dynamic_debug dyndbg=3Dclass,D2_CORE,+p

> Is this format documented somewhere?
> Will the documentation get updated?

Documentation will be updated.

> Could it break existing scripts? [*]
>

It should not break any scripts as this change does not change the
interface but extends it.

> The dynamic debug interface is really hard to use for me
> as an occasional user. I always have to look into
> Documentation/admin-guide/dynamic-debug-howto.rst
>
> Anyway, there should be a good reason to change the interface.
> And the exaplantion:
>
>    "Let's use '.' instead of ',' so that we could later
>     treat ',' as space"
>
> sounds scarry. It does not explain what is the advantage at all.
>

I will clarify in the commit message that this change allows to use
two formats either
modprobe test_dynamic_debug dyndbg=3D"class D2_CORE +p"
or
modprobe test_dynamic_debug dyndbg=3Dclass,D2_CORE,+p

>
> [*] Some scripts are using the interface even in the mainline,
> for example:
>
> $> git grep "dynamic_debug" tools/testing/
> tools/testing/selftests/bpf/test_tunnel.sh:     echo 'file ip_gre.c +p' >=
 /sys/kernel/debug/dynamic_debug/control
> tools/testing/selftests/bpf/test_tunnel.sh:     echo 'file ip6_gre.c +p' =
> /sys/kernel/debug/dynamic_debug/control
> tools/testing/selftests/bpf/test_tunnel.sh:     echo 'file geneve.c +p' >=
 /sys/kernel/debug/dynamic_debug/control
> tools/testing/selftests/bpf/test_tunnel.sh:     echo 'file ipip.c +p' > /=
sys/kernel/debug/dynamic_debug/control
> tools/testing/selftests/livepatch/functions.sh: DYNAMIC_DEBUG=3D$(grep '^=
kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \
> tools/testing/selftests/livepatch/functions.sh:         echo -n "$DYNAMIC=
_DEBUG" > /sys/kernel/debug/dynamic_debug/control
> tools/testing/selftests/livepatch/functions.sh:function set_dynamic_debug=
() {
> tools/testing/selftests/livepatch/functions.sh:        cat <<-EOF > /sys/=
kernel/debug/dynamic_debug/control
> tools/testing/selftests/livepatch/functions.sh: set_dynamic_debug
>

Good to know. I will use these scripts to make sure the dynamic debug
interface is not broken.

Thanks,
Lukasz

>
> Best Regards,
> Petr