linux-kernel - Re: [PATCH v9 30/52] drm-dyndbg: adapt drm core to use dyndbg classmaps-v2

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Message-ID: <ZoU7kR2aYwVDvd_G@intel.com>
Date: Wed, 3 Jul 2024 14:52:49 +0300
From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
To: jim.cromie@...il.com
Cc: daniel.vetter@...ll.ch, tvrtko.ursulin@...ux.intel.com,
	jani.nikula@...el.com, jbaron@...mai.com,
	gregkh@...uxfoundation.org, ukaszb@...omium.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org, linux@...musvillemoes.dk,
	joe@...ches.com, mcgrof@...nel.org
Subject: Re: [PATCH v9 30/52] drm-dyndbg: adapt drm core to use dyndbg
 classmaps-v2

On Tue, Jul 02, 2024 at 08:34:39PM -0600, jim.cromie@...il.com wrote:
> On Tue, Jul 2, 2024 at 5:33 PM Ville Syrjälä
> <ville.syrjala@...ux.intel.com> wrote:
> >
> > On Tue, Jul 02, 2024 at 03:57:20PM -0600, Jim Cromie wrote:
> > > dyndbg's CLASSMAP-v1 api was broken; DECLARE_DYNDBG_CLASSMAP tried to
> > > do too much.  Its replaced by DRM_CLASSMAP_DEFINE, which creates &
> > > EXPORTs the classmap when CONFIG_DRM_USE_DYNAMIC_DEBUG=y, for direct
> > > reference by drivers.
> > >
> > > The drivers still use DECLARE_DYNDBG_CLASSMAP for now, so they still
> > > redundantly re-declare the classmap, but we can convert the drivers
> > > later to DYNDBG_CLASSMAP_USE
> > >
> > > Signed-off-by: Jim Cromie <jim.cromie@...il.com>
> > > ---
> > >  drivers/gpu/drm/drm_print.c | 25 +++++++++++++------------
> > >  include/drm/drm_print.h     |  8 ++++++++
> > >  2 files changed, 21 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
> > > index 699b7dbffd7b..4a5f2317229b 100644
> > > --- a/drivers/gpu/drm/drm_print.c
> > > +++ b/drivers/gpu/drm/drm_print.c
> > > @@ -55,18 +55,19 @@ MODULE_PARM_DESC(debug, "Enable debug output, where each bit enables a debug cat
> > >  #if !defined(CONFIG_DRM_USE_DYNAMIC_DEBUG)
> > >  module_param_named(debug, __drm_debug, ulong, 0600);
> > >  #else
> > > -/* classnames must match vals of enum drm_debug_category */
> > > -DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
> > > -                     "DRM_UT_CORE",
> > > -                     "DRM_UT_DRIVER",
> > > -                     "DRM_UT_KMS",
> > > -                     "DRM_UT_PRIME",
> > > -                     "DRM_UT_ATOMIC",
> > > -                     "DRM_UT_VBL",
> > > -                     "DRM_UT_STATE",
> > > -                     "DRM_UT_LEASE",
> > > -                     "DRM_UT_DP",
> > > -                     "DRM_UT_DRMRES");
> > > +/* classnames must match value-symbols of enum drm_debug_category */
> > > +DRM_CLASSMAP_DEFINE(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS,
> > > +                 DRM_UT_CORE,
> > > +                 "DRM_UT_CORE",
> > > +                 "DRM_UT_DRIVER",
> > > +                 "DRM_UT_KMS",
> > > +                 "DRM_UT_PRIME",
> > > +                 "DRM_UT_ATOMIC",
> > > +                 "DRM_UT_VBL",
> > > +                 "DRM_UT_STATE",
> > > +                 "DRM_UT_LEASE",
> > > +                 "DRM_UT_DP",
> > > +                 "DRM_UT_DRMRES");
> >
> > Looks like this stuff just ends up in an array, so presumably
> > it should be possible to use designated initializers to make this
> > less fragile?
> 
> Im not sure I got your whole point, but:

I mean using
 [DRM_UT_CORE] = "DRM_UT_CORE"
instead of
 "DRM_UT_CORE"
so there is no chance of screwing up the order.
Or maybe the order doesn't even matter here?

Could also stringify to avoid accidental of typos.

> 
> the fragility is the repetitive re-statement of the map,
> in those un-modified DECLARE_s,
> once replaced, the USEs just ref the struct built by the _DEFINE
> (once, and exported)
> 
> I dont really like the _DEFINEs restatement of the enum-values: DRM_UT_*
> especially as "strings".
> I can automate the stringification with an APPLY_FN_(__stringify, ...)
> but the enum-list DRM_UT_* (w.o quotes) is still needed as args.
> 
> unless there is something C can do thats like Enum.values() ?
> 
> 
> 
> >
> > --
> > Ville Syrjälä
> > Intel

-- 
Ville Syrjälä
Intel