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From: =?UTF-8?Q?=C5=81ukasz_Bartosik?= <ukaszb@chromium.org>
Date: Tue, 21 May 2024 13:58:15 +0200
Message-ID: <CALwA+Nb8EKBRk+1ejxWhRBhoYf=Arge5TvA-mPzDD95Am+7pYw@mail.gmail.com>
Subject: Re: [PATCH v8-RESEND 22/33] dyndbg: split multi-query strings with %
To: Jim Cromie <jim.cromie@gmail.com>
Cc: jbaron@akamai.com, gregkh@linuxfoundation.org, 
	linux-kernel@vger.kernel.org, linux@rasmusvillemoes.dk, joe@perches.com, 
	mcgrof@kernel.org, daniel.vetter@ffwll.ch, tvrtko.ursulin@linux.intel.com, 
	jani.nikula@intel.com, ville.syrjala@linux.intel.com, seanpaul@chromium.org, 
	robdclark@gmail.com, groeck@google.com, yanivt@google.com, bleung@google.com
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On Thu, May 16, 2024 at 7:45=E2=80=AFPM Jim Cromie <jim.cromie@gmail.com> w=
rote:
>
> Multi-query strings have long allowed:

Missing been ?

>
>   modprobe drm dyndbg=3D"class DRM_UT_CORE +p; class DRM_UT_KMS +p"
>   modprobe drm dyndbg=3D<<EOX
>      class DRM_UT_CORE +p
>      class DRM_UT_KMS +p
>   EOX
>
> More recently, the need for quoting was avoided by treating a comma
> like a space/token-terminator:
>
>   modprobe drm dyndbg=3Dclass,DRM_UT_CORE,+p\;class,DRM_UT_KMS,+p
>
> That worked, but it left unfinished business; the semicolon in the
> example above is a shell special-char (one of the bash control
> operators), so it is brittle when passed in/down/around scripts.  In
> particular, it fails when passed to vng (virtme-ng).
>
> So this patch adds '%' to the existing ';' and '\n' multi-cmd
> separators, which is more shell-friendly, and also avoids quoting and
> escaping hassles.
>
> NOTE: it does break format matching on '%' patterns:
>
> bash-5.2# ddcmd 'format "find-me: %foo" +p'
> [  203.900581] dyndbg: read 26 bytes from userspace
> [  203.900883] dyndbg: query 0: "format "find-me: " mod:*
> [  203.901118] dyndbg: unclosed quote: find-me:
> [  203.901355] dyndbg: tokenize failed
> [  203.901529] dyndbg: query 1: "foo" +p" mod:*
> [  203.901957] dyndbg: split into words: "foo"" "+p"
> [  203.902243] dyndbg: op=3D'+' flags=3D0x1 maskp=3D0xffffffff
> [  203.902458] dyndbg: expecting pairs of match-spec <value>
> [  203.902703] dyndbg: query parse failed
> [  203.902871] dyndbg: processed 2 queries, with 0 matches, 2 errs
> bash: echo: write error: Invalid argument
>
> The '%' splits the input into 2 queries, and both fail.  Given the
> limited utility of matching against the working parts of a format
> string "foo: %d bar %s", nothing is actually lost here.
>
> Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
> ---
>  lib/dynamic_debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> index c1bc728cb050..625838bd74aa 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -596,7 +596,7 @@ static int ddebug_exec_queries(char *query, const cha=
r *modname)
>         int i, errs =3D 0, exitcode =3D 0, rc, nfound =3D 0;
>
>         for (i =3D 0; query; query =3D split) {
> -               split =3D strpbrk(query, ";\n");
> +               split =3D strpbrk(query, "%;\n");
>                 if (split)
>                         *split++ =3D '\0';
>
> --
> 2.45.0
>