Re: [PATCH 16/63] dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP

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hi Louis,

On Tue, Feb 25, 2025 at 7:16 AM Louis Chauvet <louis.chauvet@xxxxxxxxxxx> wrote:
>
>
>
> Le 25/01/2025 à 07:45, Jim Cromie a écrit :
> > DECLARE_DYNDBG_CLASSMAP() has a design error; its usage fails a basic
> > K&R rule: "define once, refer many times".
> >
> > It is used across DRM core & drivers, each use re-defines the classmap
> > understood by that module; and all must match for the modules to
> > respond together when DRM.debug categories are enabled.  This is
> > brittle; a maintenance foot-gun.
> >
> > Further, its culpable in the CONFIG_DRM_USE_DYNAMIC_DEBUG=Y
> > regression; its use in both core & drivers obfuscates the 2 roles.
> > So 1st drm.ko loads, and dyndbg initializes its DRM.debug callsites,
> > then a drm-driver loads, but too late - it missed the DRM.debug
> > enablement.
> >
> > So replace it with 2 macros:
> >    DYNDBG_CLASSMAP_DEFINE - invoked once from core - drm.ko
> >    DYNDBG_CLASSMAP_USE    - from all drm drivers and helpers.
> >
> > DYNDBG_CLASSMAP_DEFINE: it just modifies DECLARE_DYNDBG_CLASSMAP,
> > dropping drop the static qualifier, and exports it instead.
> >
> > DYNDBG_CLASSMAP_USE: then refers to the exported var by name:
> >    used from drivers, helper-mods
> >    lets us drop the repetitive "classname" declarations
> >    fixes 2nd-defn problem
> >    creates a ddebug_class_user record in new __dyndbg_class_users section
> >    this allows ddebug_add_module(etal) to handle users differently.
> >
> > DECLARE_DYNDBG_CLASSMAP is preserved temporarily, to decouple DRM
> > adaptation work and avoid compile-errs before its done.  IOW, DRM gets
> > fixed when they commit the adopt-new-api patches, and remove the
> > BROKEN marking.
> >
> > The DEFINE,USE distinction, and the separate classmap-use record,
> > allows dyndbg to initialize the driver's & helper's DRM.debug
> > callsites separately after each is modprobed.
> >
> > Basically, the classmap init-scan is repeated for classmap-users.
> >
> > To review, dyndbg's existing __dyndbg_classes[] section does:
> >
> > . catalogs the classmaps defined by a module (or builtin modules)
> > . tells dyndbg the module has class'd prdbgs, allowing >control
> > . DYNDBG_CLASSMAP_DEFINE creates classmaps in this section.
> >
> > This patch adds __dyndbg_class_users[] section:
> >
> > . catalogs uses/references to the classmap definitions.
> > . authorizes dyndbg to >control those class'd prdbgs in ref'g module.
> > . DYNDBG_CLASSMAP_USE() creates classmap-user records in this new section.
> >
> > Now ddebug_add_module(etal) can handle classmap-uses similar to (and
> > after) classmaps; when a dependent module is loaded, if it has
> > classmap-uses (to a classmap-def in another module), that module's
> > kernel params are scanned to find if it has a kparam that is wired to
> > dyndbg's param-ops, and whose classmap is the one being ref'd.
> >
> > To support this, theres a few data/header changes:
> >
> > new struct ddebug_class_user
> >    contains: user-module-name, &classmap-defn
> >    it records drm-driver's use of a classmap in the section, allowing lookup
> >
> > struct ddebug_info gets 2 new fields for the new sections:
> >    class_users, num_class_users.
> >    set by dynamic_debug_init() for builtins.
> >    or by kernel/module/main:load_info() for loadable modules.
> >
> > vmlinux.lds.h: new BOUNDED_SECTION for __dyndbg_class_users
> >
> > dynamic_debug.c has 2 changes in ddebug_add_module(), ddebug_change():
> >
> > ddebug_add_module() already calls ddebug_attach_module_classes()
> > to handle classmaps DEFINEd by a module, now it also calls
> > ddebug_attach_user_module_classes() to handle USEd classmaps.  To
> > avoid this work when possible, 1st scan the module's descriptors and
> > count the number of class'd pr_debugs.
> >
> > ddebug_attach_user_module_classes() scans the module's class_users
> > section, follows the refs to the parent's classmap, and calls
> > ddebug_apply_params() on each.  It also avoids work by checking the
> > module's class-ct.
> >
> > ddebug_apply_params(new fn):
> >
> > It scans module's/builtin kernel-params, calls ddebug_match_apply_kparam
> > for each to find any params/sysfs-nodes which may be wired to a classmap.
> >
> > ddebug_match_apply_kparam(new fn):
> >
> > 1st, it tests the kernel-param.ops is dyndbg's; this guarantees that
> > the attached arg is a struct ddebug_class_param, which has a ref to
> > the param's state, and to the classmap defining the param's handling.
> >
> > 2nd, it requires that the classmap ref'd by the kparam is the one
> > we're called for; modules can use many separate classmaps (as
> > test_dynamic_debug does).
> >
> > Then apply the "parent" kparam's setting to the dependent module,
> > using ddebug_apply_class_bitmap().
> >
> > ddebug_change(and callees) also gets adjustments:
> >
> > ddebug_find_valid_class(): This does a search over the module's
> > classmaps, looking for the class FOO echo'd to >control.  So now it
> > searches over __dyndbg_class_users[] after __dyndbg_classes[].
> >
> > ddebug_class_name(): return class-names for defined AND used classes.
> >
> > test_dynamic_debug.c, test_dynamic_debug_submod.c:
> >
> > This demonstrates the 2 types of classmaps & sysfs-params, following
> > the 4-part recipe:
> >
> > 1. define an enum for the classmap: DRM.debug has DRM_UT_{CORE,KMS,...}
> >     multiple classes must share 0-62 classid space.
> > 2. DYNDBG_CLASSMAP_DEFINE(.. DRM_UT_{CORE,KMS,...})
> > 3. DYNDBG_CLASSMAP_PARAM* (classmap)
> > 4. DYNDBG_CLASSMAP_USE()
> >     by _submod only, skipping 2,3
> >
> > Move all the enum declarations together, to better explain how they
> > share the 0..62 class-id space available to a module (non-overlapping
> > subranges).
> >
> > reorg macros 2,3 by name.  This gives a tabular format, making it easy
> > to see the pattern of repetition, and the points of change.
> >
> > And extend the test to replicate the 2-module (parent & dependent)
> > scenario which caused the CONFIG_DRM_USE_DYNAMIC_DEBUG=y regression
> > seen in drm & drivers.
> >
> > The _submod.c is a 2-line file: #define _SUBMOD, #include parent.
> >
> > This gives identical complements of prdbgs in parent & _submod, and
> > thus identical print behavior when all of: >control, >params, and
> > parent->_submod propagation are working correctly.
> >
> > It also puts all the parent/_submod declarations together in the same
> > source, with the new ifdef _SUBMOD block invoking DYNDBG_CLASSMAP_USE
> > for the 2 test-interfaces.  I think this is clearer.
> >
> > These 2 modules are both tristate, allowing 3 super/sub combos: Y/Y,
> > Y/M, M/M (not N/N).  Y/Y testing exposed a missing __align(8) in the
> > _METADATA macro, which M/M didn't see because the module-loader memory
> > placement constrains it instead.
> >
> > NB: this patch ignores a checkpatch do-while warning which is fixed by
> > a preceding commit, which would be wrong for declarative macros like
> > module_param_named() etc.
> >
> > Fixes: aad0214f3026 ("dyndbg: add DECLARE_DYNDBG_CLASSMAP macro")
> > Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
> > ---
> > v9 - commit-msg tweaks
> >       DRM:CHECK warnings on macros: add parens
> >       extern DEFINEd _var, static classnames
> >       change ddebug_class_user.user_mod_name to .mod_name
> >       simplify ddebug_find_valid_class
> >       improve vpr_cm_info msg format
> >       wrap (base) in macro body
> >       move __DYNDBG_CLASSMAP_CHECK above kdoc for DYNDBG_CLASSMAP_DEFINE
> >
> > v8 - split drm parts to separate commits.
> >       preserve DECLARE_DYNDBG_CLASSMAP to decouple DRM, no flag day.
> >       fixup block comment
> >
> > v7 - previous submission-blocking bug:
> >
> > missing __align(8) in DYNAMIC_DEBUG_DECLARE_METADATA on
> > ddebug_class_user caused corrupt records, but only for builtin
> > modules; module loader code probably pinned allocations to the right
> > alignment naturally, hiding the bug for typical builds.
> >
> > v6- get rid of WARN_ON_ONCE
> > v?- fix _var expanded 2x in macro
> >
> > dyndbg:
> >
> > This fn formerly returned the map which contained the class (thus
> > validating it), and as a side-effect set the class-id in an outvar.
> >
> > But the caller didn't use the map (after checking its not null), only
> > the valid class-id.  So simplify the fn to return the class-id of the
> > validated classname, or -ENOENT when the queried classname is not
> > found.
> >
> > Convey more useful info in the debug-msg: print class-names[0,last],
> > and [base,+len] instead of the class-type printout, which is currently
> > always "type:DISJOINT_BITS".  And drop ddebug_classmap_typenames,
> > which is now unused.
> >
> > [root@v6 b0-dd]# modprobe test_dynamic_debug_submod
> > [   18.864962] dyndbg: loaded classmap: test_dynamic_debug [16..24] V0..V7
> > [   18.865046] dyndbg:  found kp:p_level_num =0x0
> > [   18.865048] dyndbg:   mapped to: test_dynamic_debug [16..24] V0..V7
> > [   18.865164] dyndbg:   p_level_num: lvl:0 bits:0x0
> > [   18.865217] dyndbg: loaded classmap: test_dynamic_debug [0..10] D2_CORE..D2_DRMRES
> > [   18.865297] dyndbg:  found kp:p_disjoint_bits =0x0
> > [   18.865298] dyndbg:   mapped to: test_dynamic_debug [0..10] D2_CORE..D2_DRMRES
> > [   18.865424] dyndbg:   p_disjoint_bits: classbits: 0x0
> > [   18.865472] dyndbg: module:test_dynamic_debug attached 2 classmaps
> > [   18.865533] dyndbg:  23 debug prints in module test_dynamic_debug
> > [   18.866558] dyndbg: loaded classmap: test_dynamic_debug_submod [16..24] V0..V7
> > [   18.866698] dyndbg:  found kp:p_level_num =0x0
> > [   18.866699] dyndbg:   mapped to: test_dynamic_debug_submod [16..24] V0..V7
> > [   18.866865] dyndbg:   p_level_num: lvl:0 bits:0x0
> > [   18.866926] dyndbg: loaded classmap: test_dynamic_debug_submod [0..10] D2_CORE..D2_DRMRES
> > [   18.867026] dyndbg:  found kp:p_disjoint_bits =0x0
> > [   18.867027] dyndbg:   mapped to: test_dynamic_debug_submod [0..10] D2_CORE..D2_DRMRES
> > [   18.867193] dyndbg:   p_disjoint_bits: classbits: 0x0
> > [   18.867255] dyndbg: module:test_dynamic_debug_submod attached 2 classmap uses
> > [   18.867351] dyndbg:  23 debug prints in module test_dynamic_debug_submod
> > ---
> >   MAINTAINERS                       |   2 +-
> >   include/asm-generic/vmlinux.lds.h |   1 +
> >   include/linux/dynamic_debug.h     |  83 ++++++++++--
> >   kernel/module/main.c              |   3 +
> >   lib/Kconfig.debug                 |  24 +++-
> >   lib/Makefile                      |   3 +
> >   lib/dynamic_debug.c               | 203 ++++++++++++++++++++++++------
> >   lib/test_dynamic_debug.c          | 111 +++++++++++-----
> >   lib/test_dynamic_debug_submod.c   |  10 ++
>
> Hi Jim,
>
> While reading the files test_dynamic_debug*, I was wondering, they are
> more samples than tests. Does it make sense to move them in samples/?
> There is no need to do it in this series.
>
> >   9 files changed, 355 insertions(+), 85 deletions(-)
> >   create mode 100644 lib/test_dynamic_debug_submod.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 0fa7c5728f1e..38afccb3b71e 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -8041,7 +8041,7 @@ M:      Jim Cromie <jim.cromie@xxxxxxxxx>
> >   S:  Maintained
> >   F:  include/linux/dynamic_debug.h
> >   F:  lib/dynamic_debug.c
> > -F:   lib/test_dynamic_debug.c
> > +F:   lib/test_dynamic_debug*.c
> >
> >   DYNAMIC INTERRUPT MODERATION
> >   M:  Tal Gilboa <talgi@xxxxxxxxxx>
> > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> > index 54504013c749..eb93fd09832b 100644
> > --- a/include/asm-generic/vmlinux.lds.h
> > +++ b/include/asm-generic/vmlinux.lds.h
> > @@ -366,6 +366,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
> >       /* implement dynamic printk debug */                            \
> >       . = ALIGN(8);                                                   \
> >       BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes)         \
> > +     BOUNDED_SECTION_BY(__dyndbg_class_users, ___dyndbg_class_users) \
> >       BOUNDED_SECTION_BY(__dyndbg, ___dyndbg)                         \
> >       CODETAG_SECTIONS()                                              \
> >       LIKELY_PROFILE()                                                \
> > diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> > index c8102e89beb2..dc610a12b91c 100644
> > --- a/include/linux/dynamic_debug.h
> > +++ b/include/linux/dynamic_debug.h
> > @@ -71,9 +71,28 @@ enum ddebug_class_map_type {
> >        */
> >   };
> >
> > +/*

BTW, Im gonna refine this ...

> > + * dyndbg-classmaps are devised to support DRM.debug directly:
> > + *    10 enum-vals: DRM_UT_* define the categories
> > + *   ~23 categorized *_dbg() macros, each passing a DRM_UT_* val as 1st arg
> > + *     2 macros below them: drm_dev_dbg, __drm_dbg
> > + * ~5000 calls to the categorized macros, across all of drivers/gpu/drm/
> > + *
> > + * When CONFIG_DRM_USE_DYNAMIC_DEBUG=y, the 2 low macros are redefined
> > + * to invoke _dynamic_func_call_cls().  This compiles the category
> > + * into each callsite's class_id field, where dyndbg can select on it
> > + * and alter a callsite's patch-state, avoiding repeated __drm_debug
> > + * checks.
> > + *
> > + * To make the callsites manageable from the >control file, authors
> > + * provide a "classmap" of names to class_ids in use by the module(s),
> > + * usually by stringifying the enum-vals.  Modules with multiple
> > + * classmaps must arrange to share the 0..62 class_id space.
> > + */
> > +
> >   struct ddebug_class_map {
> > -     struct module *mod;
> > -     const char *mod_name;   /* needed for builtins */
> > +     const struct module *mod;               /* NULL for builtins */
> > +     const char *mod_name;
>
> Is this change belongs to this patch? If not can you move this in a
> "cleanup" patch?

It belongs, insofar as the mod field is actually NULL checked to determine
builtin vs modular, mod_name is backup.
Also its more specific than "needed for builtins"

But, grumble, ya, the above was an existing test, not a new one.
OTOH - I guess Ive just written the cleanup commit msg :-)

>
> >       const char **class_names;
> >       const int length;
> >       const int base;         /* index of 1st .class_id, allows split/shared space */
> > @@ -81,11 +100,34 @@ struct ddebug_class_map {
> >   };
> >
> >   /**
> > - * DECLARE_DYNDBG_CLASSMAP - declare classnames known by a module
> > - * @_var:   a struct ddebug_class_map, passed to module_param_cb
> > - * @_type:  enum class_map_type, chooses bits/verbose, numeric/symbolic
> > - * @_base:  offset of 1st class-name. splits .class_id space
> > - * @classes: class-names used to control class'd prdbgs
> > + * DYNDBG_CLASSMAP_DEFINE - define debug classes used by a module.
> > + * @_var:   name of the classmap, exported for other modules coordinated use.
> > + * @_mapty: enum ddebug_class_map_type: 0:DISJOINT - independent, 1:LEVEL - v2>v1> + * @_base:  reserve N classids starting at _base, to split 0..62
> classid space
> > + * @classes: names of the N classes.
> > + *
> > + * This tells dyndbg what class_ids the module is using: _base..+N, by
> > + * mapping names onto them.  This qualifies "class NAME" >controls on
> > + * the defining module, ignoring unknown names.
> > + */
> > +#define DYNDBG_CLASSMAP_DEFINE(_var, _mapty, _base, ...)             \
> > +     static const char *_var##_classnames[] = { __VA_ARGS__ };       \
> > +     extern struct ddebug_class_map _var;                            \
> > +     struct ddebug_class_map __aligned(8) __used                     \
> > +             __section("__dyndbg_classes") _var = {                  \
> > +             .mod = THIS_MODULE,                                     \
> > +             .mod_name = KBUILD_MODNAME,                             \
> > +             .base = (_base),                                        \
> > +             .map_type = (_mapty),                                   \
> > +             .length = ARRAY_SIZE(_var##_classnames),                \
> > +             .class_names = _var##_classnames,                       \
> > +     };                                                              \
> > +     EXPORT_SYMBOL(_var)
> > +
> > +/*
> > + * XXX: keep this until DRM adapts to use the DEFINE/USE api, it
> > + * differs from DYNDBG_CLASSMAP_DEFINE by the static replacing the
> > + * extern/EXPORT on the struct init.
> >    */
> >   #define DECLARE_DYNDBG_CLASSMAP(_var, _maptype, _base, ...)         \
> >       static const char *_var##_classnames[] = { __VA_ARGS__ };       \
> > @@ -99,12 +141,37 @@ struct ddebug_class_map {
> >               .class_names = _var##_classnames,                       \
> >       }
> >
> > +struct ddebug_class_user {
> > +     char *mod_name;
> > +     struct ddebug_class_map *map;
> > +};
> > +
> > +/**
> > + * DYNDBG_CLASSMAP_USE - refer to a classmap, DEFINEd elsewhere.
> > + * @_var: name of the exported classmap var
> > + *
> > + * This tells dyndbg that the module has prdbgs with classids defined
> > + * in the named classmap.  This qualifies "class NAME" >controls on
> > + * the user module, ignoring unknown names.
> > + */
> > +#define DYNDBG_CLASSMAP_USE(_var)                                    \
> > +     DYNDBG_CLASSMAP_USE_(_var, __UNIQUE_ID(ddebug_class_user))
> > +#define DYNDBG_CLASSMAP_USE_(_var, _uname)                           \
> > +     extern struct ddebug_class_map _var;                            \
> > +     static struct ddebug_class_user __aligned(8) __used             \
> > +     __section("__dyndbg_class_users") _uname = {                    \
> > +             .mod_name = KBUILD_MODNAME,                             \
> > +             .map = &(_var),                                         \
> > +     }
> > +
>
> I'm not sure I understand properly how __section works, but can we use
> multiple DYNDBG_CLASSMAP_USE in one module? Can we also use
> DYNDBG_CLASSMAP_DEFINE while also importing an other classmap
> DYNDBG_CLASSMAP_USE?
>

Yes, its supposed to work that way.

I havent tested that specific scenario (yet), but
a _USEr module, like test-dynamic-debug-submod,
could also _DEFINE its own, as long as it honors
the class-id mapping it is using and therefore sharing.
The on-modprobe conflict check should catch this condition.

And __section (ISTM) accumulates entries, typically static struct var
initializations.
AFAICT, scanning the sections is how these { scoped statics } are
often reachable.

For example, dd's _METADATA_ builds a { static _ddebug } for every pr_debug.
They all go into the __dyndbg section (renamed with _descriptors suffix soon),
in the order their respective definer objects are linked.

include/asm-generic/vmlinux.lds.h  then places the __dyndbg_* sections
into DATA, along with lots of other freight, for the various
mechanisms they serve.




> If not, does it make sense to allow it (for example MFD devices can
> touch multiple subsystems)?

We have another use case !
Do you know your way around that case ?

Note that DEFINEr  & USEr calls set up linkage dependencies,
As long as these are consistent with other module deps,
it should work.


>
> >   /* encapsulate linker provided built-in (or module) dyndbg data */
> >   struct _ddebug_info {
> >       struct _ddebug *descs;
> >       struct ddebug_class_map *classes;
> > +     struct ddebug_class_user *class_users;
> >       unsigned int num_descs;
> >       unsigned int num_classes;
> > +     unsigned int num_class_users;
> >   };
> >
> >   struct ddebug_class_param {
> > @@ -205,7 +272,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
> >    * (|_no_desc):     former gets callsite descriptor as 1st arg (for prdbgs)
> >    */
> >   #define __dynamic_func_call_cls(id, cls, fmt, func, ...) do {       \
> > -     DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);        \
> > +     DEFINE_DYNAMIC_DEBUG_METADATA_CLS((id), cls, fmt);      \
>
> Can you move this in a "cleanup" patch?
>
> >       if (DYNAMIC_DEBUG_BRANCH(id))                           \
> >               func(&id, ##__VA_ARGS__);                       \
> >   } while (0)
> > diff --git a/kernel/module/main.c b/kernel/module/main.c
> > index 5399c182b3cb..c394a0c6e8c6 100644
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -2546,6 +2546,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
> >       mod->dyndbg_info.classes = section_objs(info, "__dyndbg_classes",
> >                                               sizeof(*mod->dyndbg_info.classes),
> >                                               &mod->dyndbg_info.num_classes);
> > +     mod->dyndbg_info.class_users = section_objs(info, "__dyndbg_class_users",
> > +                                                 sizeof(*mod->dyndbg_info.class_users),
> > +                                                &mod->dyndbg_info.num_class_users);
> >   #endif
> >
> >       return 0;
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index f3d723705879..933f69ef87f8 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -2884,12 +2884,26 @@ config TEST_STATIC_KEYS
> >         If unsure, say N.
> >
> >   config TEST_DYNAMIC_DEBUG
> > -     tristate "Test DYNAMIC_DEBUG"
> > -     depends on DYNAMIC_DEBUG
> > +     tristate "Build test-dynamic-debug module"
> > +     depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
> >       help
> > -       This module registers a tracer callback to count enabled
> > -       pr_debugs in a 'do_debugging' function, then alters their
> > -       enablements, calls the function, and compares counts.
> > +       This module exercises/demonstrates dyndbg's classmap API, by
> > +       creating 2 classes: a DISJOINT classmap (supporting DRM.debug)
> > +       and a LEVELS/VERBOSE classmap (like verbose2 > verbose1).
> > +
> > +       If unsure, say N.
> > +
> > +config TEST_DYNAMIC_DEBUG_SUBMOD
> > +     tristate "Build test-dynamic-debug submodule"
> > +     default m
> > +     depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
> > +     depends on TEST_DYNAMIC_DEBUG
> > +     help
> > +       This sub-module uses a classmap defined and exported by the
> > +       parent module, recapitulating drm & driver's shared use of
> > +       drm.debug to control enabled debug-categories.
> > +       It is tristate, independent of parent, to allow testing all
> > +       proper combinations of parent=y/m submod=y/m.
> >
> >         If unsure, say N.
> >
> > diff --git a/lib/Makefile b/lib/Makefile
> > index a8155c972f02..7f66fc1c163d 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -84,6 +84,7 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o
> >   obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
> >   obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
> >   obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
> > +obj-$(CONFIG_TEST_DYNAMIC_DEBUG_SUBMOD) += test_dynamic_debug_submod.o
> >   obj-$(CONFIG_TEST_PRINTF) += test_printf.o
> >   obj-$(CONFIG_TEST_SCANF) += test_scanf.o
> >
> > @@ -228,6 +229,8 @@ obj-$(CONFIG_ARCH_NEED_CMPXCHG_1_EMU) += cmpxchg-emu.o
> >   obj-$(CONFIG_DYNAMIC_DEBUG_CORE) += dynamic_debug.o
> >   #ensure exported functions have prototypes
> >   CFLAGS_dynamic_debug.o := -DDYNAMIC_DEBUG_MODULE
> > +CFLAGS_test_dynamic_debug.o := -DDYNAMIC_DEBUG_MODULE
> > +CFLAGS_test_dynamic_debug_submod.o := -DDYNAMIC_DEBUG_MODULE
> >
> >   obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o
> >
> > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> > index 094d6e62a9d1..6bca0c6727d4 100644
> > --- a/lib/dynamic_debug.c
> > +++ b/lib/dynamic_debug.c
> > @@ -43,13 +43,16 @@ extern struct _ddebug __start___dyndbg[];
> >   extern struct _ddebug __stop___dyndbg[];
> >   extern struct ddebug_class_map __start___dyndbg_classes[];
> >   extern struct ddebug_class_map __stop___dyndbg_classes[];
> > +extern struct ddebug_class_user __start___dyndbg_class_users[];
> > +extern struct ddebug_class_user __stop___dyndbg_class_users[];
> >
> >   struct ddebug_table {
> >       struct list_head link;
> >       const char *mod_name;
> >       struct _ddebug *ddebugs;
> >       struct ddebug_class_map *classes;
> > -     unsigned int num_ddebugs, num_classes;
> > +     struct ddebug_class_user *class_users;
> > +     unsigned int num_ddebugs, num_classes, num_class_users;
> >   };
> >
> >   struct ddebug_query {
> > @@ -148,23 +151,35 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> >                 query->first_lineno, query->last_lineno, query->class_string);
> >   }
> >
> > -#define __outvar /* filled by callee */
> > -static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
> > -                                                     const char *class_string,
> > -                                                     __outvar int *class_id)
> > +#define vpr_dt_info(dt_p, msg_p, ...) ({                             \
> > +     struct ddebug_table const *_dt = dt_p;                          \
> > +     v2pr_info(msg_p " module:%s nd:%d nc:%d nu:%d\n", ##__VA_ARGS__, \
> > +               _dt->mod_name, _dt->num_ddebugs, _dt->num_classes,    \
> > +               _dt->num_class_users);                                \
> > +     })
> > +
> > +static int ddebug_find_valid_class(struct ddebug_table const *dt, const char *class_string)
> >   {
> >       struct ddebug_class_map *map;
> > +     struct ddebug_class_user *cli;
> >       int i, idx;
> >
> > -     for (map = dt->classes, i = 0; i < dt->num_classes; i++, map++) {
> > +     for (i = 0, map = dt->classes; i < dt->num_classes; i++, map++) {
> >               idx = match_string(map->class_names, map->length, class_string);
> >               if (idx >= 0) {
> > -                     *class_id = idx + map->base;
> > -                     return map;
> > +                     vpr_dt_info(dt, "good-class: %s.%s ", map->mod_name, class_string);
> > +                     return idx + map->base;
> >               }
> >       }
> > -     *class_id = -ENOENT;
> > -     return NULL;
> > +     for (i = 0, cli = dt->class_users; i < dt->num_class_users; i++, cli++) {
> > +             idx = match_string(cli->map->class_names, cli->map->length, class_string);
> > +             if (idx >= 0) {
> > +                     vpr_dt_info(dt, "class-ref: %s -> %s.%s ",
> > +                                 cli->mod_name, cli->map->mod_name, class_string);
> > +                     return idx + cli->map->base;
> > +             }
> > +     }
> > +     return -ENOENT;
> >   }
> >
> >   /*
> > @@ -173,16 +188,14 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
> >    * callsites, normally the same as number of changes.  If verbose,
> >    * logs the changes.  Takes ddebug_lock.
> >    */
> > -static int ddebug_change(const struct ddebug_query *query,
> > -                      struct flag_settings *modifiers)
> > +static int ddebug_change(const struct ddebug_query *query, struct flag_settings *modifiers)
> >   {
> >       int i;
> >       struct ddebug_table *dt;
> >       unsigned int newflags;
> >       unsigned int nfound = 0;
> >       struct flagsbuf fbuf, nbuf;
> > -     struct ddebug_class_map *map = NULL;
> > -     int __outvar valid_class;
> > +     int valid_class;
> >
> >       /* search for matching ddebugs */
> >       mutex_lock(&ddebug_lock);
> > @@ -194,8 +207,8 @@ static int ddebug_change(const struct ddebug_query *query,
> >                       continue;
> >
> >               if (query->class_string) {
> > -                     map = ddebug_find_valid_class(dt, query->class_string, &valid_class);
> > -                     if (!map)
> > +                     valid_class = ddebug_find_valid_class(dt, query->class_string);
> > +                     if (valid_class < 0)
> >                               continue;
> >               } else {
> >                       /* constrain query, do not touch class'd callsites */
> > @@ -559,7 +572,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
> >
> >   /* handle multiple queries in query string, continue on error, return
> >      last error or number of matching callsites.  Module name is either
> > -   in param (for boot arg) or perhaps in query string.
> > +   in the modname arg (for boot args) or perhaps in query string.
> >   */
> >   static int ddebug_exec_queries(char *query, const char *modname)
> >   {
> > @@ -688,12 +701,12 @@ static int param_set_dyndbg_module_classes(const char *instr,
> >   }
> >
> >   /**
> > - * param_set_dyndbg_classes - class FOO >control
> > + * param_set_dyndbg_classes - set all classes in a classmap
> >    * @instr: string echo>d to sysfs, input depends on map_type
> > - * @kp:    kp->arg has state: bits/lvl, map, map_type
> > + * @kp:    kp->arg has state: bits/lvl, classmap, map_type
> >    *
> > - * Enable/disable prdbgs by their class, as given in the arguments to
> > - * DECLARE_DYNDBG_CLASSMAP.  For LEVEL map-types, enforce relative
> > + * For all classes in the classmap, enable/disable them per the input
> > + * (depending on map_type).  For LEVEL map-types, enforce relative
> >    * levels by bitpos.
> >    *
> >    * Returns: 0 or <0 if error.
> > @@ -1038,12 +1051,17 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
> >   static const char *ddebug_class_name(struct ddebug_table *dt, struct _ddebug *dp)
> >   {
> >       struct ddebug_class_map *map = dt->classes;
> > +     struct ddebug_class_user *cli = dt->class_users;
> >       int i;
> >
> >       for (i = 0; i < dt->num_classes; i++, map++)
> >               if (class_in_range(dp->class_id, map))
> >                       return map->class_names[dp->class_id - map->base];
> >
> > +     for (i = 0; i < dt->num_class_users; i++, cli++)
> > +             if (class_in_range(dp->class_id, cli->map))
> > +                     return cli->map->class_names[dp->class_id - cli->map->base];
> > +
> >       return NULL;
> >   }
> >
> > @@ -1124,31 +1142,129 @@ static const struct proc_ops proc_fops = {
> >       .proc_write = ddebug_proc_write
> >   };
> >
> > -static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug_info *di)
> > +#define vpr_cm_info(cm_p, msg_fmt, ...) ({                           \
> > +     struct ddebug_class_map const *_cm = cm_p;                      \
> > +     v2pr_info(msg_fmt " %s [%d..%d] %s..%s\n", ##__VA_ARGS__,       \
> > +               _cm->mod_name, _cm->base, _cm->base + _cm->length,    \
> > +               _cm->class_names[0], _cm->class_names[_cm->length - 1]); \
> > +     })
> > +
> > +static void ddebug_sync_classbits(const struct kernel_param *kp, const char *modname)
> > +{
> > +     const struct ddebug_class_param *dcp = kp->arg;
> > +
> > +     /* clamp initial bitvec, mask off hi-bits */
> > +     if (*dcp->bits & ~CLASSMAP_BITMASK(dcp->map->length)) {
> > +             *dcp->bits &= CLASSMAP_BITMASK(dcp->map->length);
> > +             v2pr_info("preset classbits: %lx\n", *dcp->bits);
> > +     }
> > +     /* force class'd prdbgs (in USEr module) to match (DEFINEr module) class-param */
> > +     ddebug_apply_class_bitmap(dcp, dcp->bits, ~0, modname);
> > +     ddebug_apply_class_bitmap(dcp, dcp->bits, 0, modname);
> > +}
> > +
> > +static void ddebug_match_apply_kparam(const struct kernel_param *kp,
> > +                                   const struct ddebug_class_map *map,
> > +                                   const char *modnm)
> > +{
> > +     struct ddebug_class_param *dcp;
> > +
> > +     if (kp->ops != &param_ops_dyndbg_classes)
> > +             return;
> > +
> > +     dcp = (struct ddebug_class_param *)kp->arg;
> > +
> > +     if (map == dcp->map) {
> > +             v2pr_info(" kp:%s.%s =0x%lx", modnm, kp->name, *dcp->bits);
> > +             vpr_cm_info(map, " %s mapped to: ", modnm);
> > +             ddebug_sync_classbits(kp, modnm);
> > +     }
> > +}
> > +
> > +static void ddebug_apply_params(const struct ddebug_class_map *cm, const char *modnm)
> > +{
> > +     const struct kernel_param *kp;
> > +#if IS_ENABLED(CONFIG_MODULES)
> > +     int i;
> > +
> > +     if (cm->mod) {
> > +             vpr_cm_info(cm, "loaded classmap: %s", modnm);
> > +             /* ifdef protects the cm->mod->kp deref */
> > +             for (i = 0, kp = cm->mod->kp; i < cm->mod->num_kp; i++, kp++)
> > +                     ddebug_match_apply_kparam(kp, cm, modnm);
> > +     }
> > +#endif
> > +     if (!cm->mod) {
> > +             vpr_cm_info(cm, "builtin classmap: %s", modnm);
> > +             for (kp = __start___param; kp < __stop___param; kp++)
> > +                     ddebug_match_apply_kparam(kp, cm, modnm);
> > +     }
> > +}
> > +
> > +/*
> > + * Find this module's classmaps in a sub/whole-range of the builtin/
> > + * modular classmap vector/section.  Save the start and length of the
> > + * subrange at its edges.
> > + */
> > +static void ddebug_attach_module_classes(struct ddebug_table *dt,
> > +                                      const struct _ddebug_info *di)
> >   {
> >       struct ddebug_class_map *cm;
> >       int i, nc = 0;
> >
> > -     /*
> > -      * Find this module's classmaps in a subrange/wholerange of
> > -      * the builtin/modular classmap vector/section.  Save the start
> > -      * and length of the subrange at its edges.
> > -      */
> > -     for (cm = di->classes, i = 0; i < di->num_classes; i++, cm++) {
> > -
> > +     for (i = 0, cm = di->classes; i < di->num_classes; i++, cm++) {
> >               if (!strcmp(cm->mod_name, dt->mod_name)) {
> > -                     if (!nc) {
> > -                             v2pr_info("start subrange, class[%d]: module:%s base:%d len:%d ty:%d\n",
> > -                                       i, cm->mod_name, cm->base, cm->length, cm->map_type);
> > +                     vpr_cm_info(cm, "classes[%d]:", i);
> > +                     if (!nc++)
> >                               dt->classes = cm;
> > -                     }
> > -                     nc++;
> >               }
> >       }
> > -     if (nc) {
> > -             dt->num_classes = nc;
> > -             vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
> > +     if (!nc)
> > +             return;
> > +
> > +     vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
> > +     dt->num_classes = nc;
> > +
> > +     for (i = 0, cm = dt->classes; i < dt->num_classes; i++, cm++)
> > +             ddebug_apply_params(cm, cm->mod_name);
> > +}
> > +
> > +/*
> > + * propagates class-params thru their classmaps to class-users.  this
> > + * means a query against the dt/module, which means it must be on the
> > + * list to be seen by ddebug_change.
> > + */
> > +static void ddebug_attach_user_module_classes(struct ddebug_table *dt,
> > +                                           const struct _ddebug_info *di)
> > +{
> > +     struct ddebug_class_user *cli;
> > +     int i, nc = 0;
> > +
> > +     /*
> > +      * For builtins: scan the array, find start/length of this
> > +      * module's refs, save to dt.  For loadables, this is the
> > +      * whole array.
> > +      */
> > +     for (i = 0, cli = di->class_users; i < di->num_class_users; i++, cli++) {
> > +             if (WARN_ON_ONCE(!cli || !cli->map || !cli->mod_name))
> > +                     continue;
> > +             if (!strcmp(cli->mod_name, dt->mod_name)) {
> > +                     vpr_cm_info(cli->map, "class_ref[%d] %s -> %s", i,
> > +                                 cli->mod_name, cli->map->mod_name);
> > +                     if (!nc++)
> > +                             dt->class_users = cli;
> > +             }
> >       }
> > +     if (!nc)
> > +             return;
> > +
> > +     dt->num_class_users = nc;
> > +
> > +     /* now iterate dt */
> > +     for (i = 0, cli = dt->class_users; i < dt->num_class_users; i++, cli++)
> > +             ddebug_apply_params(cli->map, cli->mod_name);
> > +
> > +     vpr_dt_info(dt, "attach-client-module: ");
> >   }
> >
> >   /*
> > @@ -1158,6 +1274,8 @@ static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug
> >   static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> >   {
> >       struct ddebug_table *dt;
> > +     struct _ddebug *iter;
> > +     int i, class_ct = 0;
> >
> >       if (!di->num_descs)
> >               return 0;
> > @@ -1181,13 +1299,20 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> >
> >       INIT_LIST_HEAD(&dt->link);
> >
> > -     if (di->classes && di->num_classes)
> > +     for (i = 0, iter = di->descs; i < di->num_descs; i++, iter++)
> > +             if (iter->class_id != _DPRINTK_CLASS_DFLT)
> > +                     class_ct++;
> > +
> > +     if (class_ct && di->num_classes)
> >               ddebug_attach_module_classes(dt, di);
> >
> >       mutex_lock(&ddebug_lock);
> >       list_add_tail(&dt->link, &ddebug_tables);
> >       mutex_unlock(&ddebug_lock);
> >
> > +     if (class_ct && di->num_class_users)
> > +             ddebug_attach_user_module_classes(dt, di);
> > +
> >       vpr_info("%3u debug prints in module %s\n", di->num_descs, modname);
> >       return 0;
> >   }
> > @@ -1337,8 +1462,10 @@ static int __init dynamic_debug_init(void)
> >       struct _ddebug_info di = {
> >               .descs = __start___dyndbg,
> >               .classes = __start___dyndbg_classes,
> > +             .class_users = __start___dyndbg_class_users,
> >               .num_descs = __stop___dyndbg - __start___dyndbg,
> >               .num_classes = __stop___dyndbg_classes - __start___dyndbg_classes,
> > +             .num_class_users = __stop___dyndbg_class_users - __start___dyndbg_class_users,
> >       };
> >
> >   #ifdef CONFIG_MODULES
> > diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
> > index 74d183ebf3e0..1838f62738c4 100644
> > --- a/lib/test_dynamic_debug.c
> > +++ b/lib/test_dynamic_debug.c
> > @@ -6,11 +6,15 @@
> >    *      Jim Cromie  <jim.cromie@xxxxxxxxx>
> >    */
> >
> > -#define pr_fmt(fmt) "test_dd: " fmt
> > +#if defined(TEST_DYNAMIC_DEBUG_SUBMOD)
> > +  #define pr_fmt(fmt) "test_dd_submod: " fmt
> > +#else
> > +  #define pr_fmt(fmt) "test_dd: " fmt
> > +#endif
> >
> >   #include <linux/module.h>
> >
> > -/* run tests by reading or writing sysfs node: do_prints */
> > +/* re-gen output by reading or writing sysfs node: do_prints */
> >
> >   static void do_prints(void); /* device under test */
> >   static int param_set_do_prints(const char *instr, const struct kernel_param *kp)
> > @@ -29,24 +33,39 @@ static const struct kernel_param_ops param_ops_do_prints = {
> >   };
> >   module_param_cb(do_prints, &param_ops_do_prints, NULL, 0600);
> >
> > -/*
> > - * Using the CLASSMAP api:
> > - * - classmaps must have corresponding enum
> > - * - enum symbols must match/correlate with class-name strings in the map.
> > - * - base must equal enum's 1st value
> > - * - multiple maps must set their base to share the 0-30 class_id space !!
> > - *   (build-bug-on tips welcome)
> > - * Additionally, here:
> > - * - tie together sysname, mapname, bitsname, flagsname
> > - */
> > -#define DD_SYS_WRAP(_model, _flags)                                  \
> > -     static unsigned long bits_##_model;                             \
> > -     static struct ddebug_class_param _flags##_model = {             \
> > +#define CLASSMAP_BITMASK(width, base) (((1UL << (width)) - 1) << (base))
> > +
> > +/* sysfs param wrapper, proto-API */
> > +#define DYNDBG_CLASSMAP_PARAM_(_model, _flags, _init)                        \
> > +     static unsigned long bits_##_model = _init;                     \
> > +     static struct ddebug_class_param _flags##_##_model = {          \
> >               .bits = &bits_##_model,                                 \
> >               .flags = #_flags,                                       \
> >               .map = &map_##_model,                                   \
> >       };                                                              \
> > -     module_param_cb(_flags##_##_model, &param_ops_dyndbg_classes, &_flags##_model, 0600)
> > +     module_param_cb(_flags##_##_model, &param_ops_dyndbg_classes,   \
> > +                     &_flags##_##_model, 0600)
> > +#ifdef DEBUG
> > +#define DYNDBG_CLASSMAP_PARAM(_model, _flags)  DYNDBG_CLASSMAP_PARAM_(_model, _flags, ~0)
> > +#else
> > +#define DYNDBG_CLASSMAP_PARAM(_model, _flags)  DYNDBG_CLASSMAP_PARAM_(_model, _flags, 0)
> > +#endif
> > +
> > +/*
> > + * Demonstrate/test all 4 class-typed classmaps with a sys-param.
> > + *
> > + * Each is 3 part: client-enum decl, _DEFINE, _PARAM.
> > + * Declare them in blocks to show patterns of use (repetitions and
> > + * changes) within each.
> > + *
> > + * 1st, dyndbg expects a client-provided enum-type as source of
> > + * category/classid truth.  DRM has DRM_UT_<CORE,DRIVER,KMS,etc>.
> > + *
> > + * Modules with multiple CLASSMAPS must have enums with distinct
> > + * value-ranges, arranged below with explicit enum_sym = X inits.
> > + *
> > + * Declare all 4 enums now, for different types
> > + */
> >
> >   /* numeric input, independent bits */
> >   enum cat_disjoint_bits {
> > @@ -60,26 +79,51 @@ enum cat_disjoint_bits {
> >       D2_LEASE,
> >       D2_DP,
> >       D2_DRMRES };
> > -DECLARE_DYNDBG_CLASSMAP(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS, 0,
> > -                     "D2_CORE",
> > -                     "D2_DRIVER",
> > -                     "D2_KMS",
> > -                     "D2_PRIME",
> > -                     "D2_ATOMIC",
> > -                     "D2_VBL",
> > -                     "D2_STATE",
> > -                     "D2_LEASE",
> > -                     "D2_DP",
> > -                     "D2_DRMRES");
> > -DD_SYS_WRAP(disjoint_bits, p);
> > -DD_SYS_WRAP(disjoint_bits, T);
> >
> >   /* numeric verbosity, V2 > V1 related */
> >   enum cat_level_num { V0 = 14, V1, V2, V3, V4, V5, V6, V7 };
> > -DECLARE_DYNDBG_CLASSMAP(map_level_num, DD_CLASS_TYPE_LEVEL_NUM, 14,
> > -                    "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7");
> > -DD_SYS_WRAP(level_num, p);
> > -DD_SYS_WRAP(level_num, T);
> > +
> > +/* recapitulate DRM's parent(drm.ko) <-- _submod(drivers,helpers) */
> > +#if !defined(TEST_DYNAMIC_DEBUG_SUBMOD)
>
> It was not clear at first read that the test_dynamic_debug.c code is
> used twice.
>

Yes, that was a miss.  Now in big comment block at the top of both,
right before the pr-fmt  mod-name shortening for the logs.


> What do you think about creating a third file "common" with
> do_prints/do_levels/... implementations and avoid this #if !defined?
>

I'd rather not.  I think the multi-module usage is sufficiently interconnected
(common enum, parent side, clone side) that all-in-one presentation
helps to communicate this "linkage".

I hope the new comments clearly elucidate this.  PLMK if not.

> > +/*
> > + * In single user, or parent / coordinator (drm.ko) modules, define
> > + * classmaps on the client enums above, and then declares the PARAMS
> > + * ref'g the classmaps.  Each is exported.
> > + */
> > +DYNDBG_CLASSMAP_DEFINE(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS,
>
> map_disjoint_bits is defined in both test_dynamic_debug.c and
> test_dynamic_debug_submodule.c, is it normal/required?

Its the enum : cat_disjoint_bits, that is defined for both.

the _DEFINE itself is right after the ifdef TEST_MOD_SUBMOD.

do you think it needs a better MOD_SUBMOD name ?
or an ifndef ?

>
> > +                    D2_CORE,
> > +                    "D2_CORE",
> > +                    "D2_DRIVER",
> > +                    "D2_KMS",
> > +                    "D2_PRIME",
> > +                    "D2_ATOMIC",
> > +                    "D2_VBL",
> > +                    "D2_STATE",
> > +                    "D2_LEASE",
> > +                    "D2_DP",
> > +                    "D2_DRMRES");
> > +
> > +DYNDBG_CLASSMAP_DEFINE(map_level_num, DD_CLASS_TYPE_LEVEL_NUM,
> > +                    V0, "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7");
> > +
> > +/*
> > + * now add the sysfs-params
> > + */
> > +
> > +DYNDBG_CLASSMAP_PARAM(disjoint_bits, p);
> > +DYNDBG_CLASSMAP_PARAM(level_num, p);
> > +
> > +#else /* TEST_DYNAMIC_DEBUG_SUBMOD */
> > +
> > +/*
> > + * in submod/drm-drivers, use the classmaps defined in top/parent
> > + * module above.
> > + */
> > +
> > +DYNDBG_CLASSMAP_USE(map_disjoint_bits);
> > +DYNDBG_CLASSMAP_USE(map_level_num);
> > +
> > +#endif
> >
> >   /* stand-in for all pr_debug etc */
> >   #define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n")
> > @@ -115,6 +159,7 @@ static void do_levels(void)
> >
> >   static void do_prints(void)
> >   {
> > +     pr_debug("do_prints:\n");
> >       do_cats();
> >       do_levels();
>
> I just observed it, is the ordering of logs garanteed in
> /proc/dynamic_debug/control?
>

Yes. the fully ordered table/__section is pretty important.
If its not true for descriptors, its probably not true for class-maps
or users either
and the list-iter --> vector-block conversion a few commits ago isnt
solid either.

its also an explicit assumption under these commits

773beabbb8e8 dyndbg: reverse module.callsite walk in cat control
2ad556f70043 dyndbg: reverse module walk in cat control

All in all, I think something would have broken by now.


> When I run this test, I have this order:
>
> do_cats =_ "doing categories\n"
> [...]
> do_levels =_ "doing levels\n"
> [...]
> do_prints =_ "do_prints:\n"
> test_dynamic_debug_init =_ "init start\n"
> test_dynamic_debug_init =_ "init done\n"
> test_dynamic_debug_exit =_ "exited\n"
>
> Which is clearly not the code execution order.

Youre correct.
the control file reflects compile link order.

Im pretty sure the appearance of init 1st in control derives from init/builtin.a
being built 1st and/or linked 1st.

>
> >   }
> > diff --git a/lib/test_dynamic_debug_submod.c b/lib/test_dynamic_debug_submod.c
> > new file mode 100644
> > index 000000000000..9a893402ce1a
> > --- /dev/null
> > +++ b/lib/test_dynamic_debug_submod.c
> > @@ -0,0 +1,10 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Kernel module for testing dynamic_debug
> > + *
> > + * Authors:
> > + *      Jim Cromie   <jim.cromie@xxxxxxxxx>
> > + */
> > +
> > +#define TEST_DYNAMIC_DEBUG_SUBMOD
> > +#include "test_dynamic_debug.c"
>
> --
> Louis Chauvet, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>

thanks again Lous,
Jim




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