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Message-ID: <CAJfuBxxzXoKummiBDGODidpRj7Fm2UDip-T0qkB7L9tscK0zCQ@mail.gmail.com>
Date: Sun, 16 Mar 2025 15:14:38 -0600
From: jim.cromie@...il.com
To: Jim Cromie <jim.cromie@...il.com>, linux-kernel@...r.kernel.org, jbaron@...mai.com,
gregkh@...uxfoundation.org, ukaszb@...omium.org,
intel-gfx-trybot@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org, daniel.vetter@...ll.ch,
tvrtko.ursulin@...ux.intel.com, jani.nikula@...el.com,
ville.syrjala@...ux.intel.com
Subject: Re: [PATCH 28/63] dyndbg-API: promote DYNDBG_CLASSMAP_PARAM to API
On Tue, Feb 25, 2025 at 7:29 AM Louis Chauvet <louis.chauvet@...tlin.com> wrote:
>
>
>
> Le 25/01/2025 à 07:45, Jim Cromie a écrit :
> > move the DYNDBG_CLASSMAP_PARAM macro from test-dynamic-debug.c into
> > the header, and refine it, by distinguishing the 2 use cases:
> >
> > 1.DYNDBG_CLASSMAP_PARAM_REF
> > for DRM, to pass in extern __drm_debug by name.
> > dyndbg keeps bits in it, so drm can still use it as before
> >
> > 2.DYNDBG_CLASSMAP_PARAM
> > new user (test_dynamic_debug) doesn't need to share state,
> > decls a static long unsigned int to store the bitvec.
> >
> > __DYNDBG_CLASSMAP_PARAM
> > bottom layer - allocate,init a ddebug-class-param, module-param-cb.
> >
> > Modify ddebug_sync_classbits() argtype deref inside the fn, to give
> > access to all kp members.
> >
> > Also clean up and improve comments in test-code, and add
> > MODULE_DESCRIPTIONs.
> >
> > Signed-off-by: Jim Cromie <jim.cromie@...il.com>
> > ---
> >
> > -v9
> > - fixup drm-print.h add PARAM_REF forwarding macros
> > with DYNDBG_CLASSMAP_PARAM_REF in the API, add DRM_ variant
> > ---
> > include/linux/dynamic_debug.h | 38 +++++++++++++++++++++
> > lib/dynamic_debug.c | 60 ++++++++++++++++++++++-----------
> > lib/test_dynamic_debug.c | 59 +++++++++++++-------------------
> > lib/test_dynamic_debug_submod.c | 9 ++++-
> > 4 files changed, 111 insertions(+), 55 deletions(-)
> >
> > diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> > index 48d76a273f68..b47d1088b7ad 100644
> > --- a/include/linux/dynamic_debug.h
> > +++ b/include/linux/dynamic_debug.h
> > @@ -205,6 +205,44 @@ struct ddebug_class_param {
> > const struct ddebug_class_map *map;
> > };
> >
> > +/**
> > + * DYNDBG_CLASSMAP_PARAM - control a ddebug-classmap from a sys-param
> > + * @_name: sysfs node name
> > + * @_var: name of the classmap var defining the controlled classes/bits
> > + * @_flags: flags to be toggled, typically just 'p'
> > + *
> > + * Creates a sysfs-param to control the classes defined by the
> > + * exported classmap, with bits 0..N-1 mapped to the classes named.
> > + * This version keeps class-state in a private long int.
> > + */
> > +#define DYNDBG_CLASSMAP_PARAM(_name, _var, _flags) \
> > + static unsigned long _name##_bvec; \
> > + __DYNDBG_CLASSMAP_PARAM(_name, _name##_bvec, _var, _flags)
> > +
> > +/**
> > + * DYNDBG_CLASSMAP_PARAM_REF - wrap a classmap with a controlling sys-param
> > + * @_name: sysfs node name
> > + * @_bits: name of the module's unsigned long bit-vector, ex: __drm_debug
> > + * @_var: name of the (exported) classmap var defining the classes/bits
> > + * @_flags: flags to be toggled, typically just 'p'
> > + *
> > + * Creates a sysfs-param to control the classes defined by the
> > + * exported clasmap, with bits 0..N-1 mapped to the classes named.
> > + * This version keeps class-state in user @_bits. This lets drm check
> > + * __drm_debug elsewhere too.
> > + */
> > +#define DYNDBG_CLASSMAP_PARAM_REF(_name, _bits, _var, _flags) \
> > + __DYNDBG_CLASSMAP_PARAM(_name, _bits, _var, _flags)
> > +
> > +#define __DYNDBG_CLASSMAP_PARAM(_name, _bits, _var, _flags) \
> > + static struct ddebug_class_param _name##_##_flags = { \
> > + .bits = &(_bits), \
> > + .flags = #_flags, \
> > + .map = &(_var), \
> > + }; \
> > + module_param_cb(_name, ¶m_ops_dyndbg_classes, \
> > + &_name##_##_flags, 0600)
> > +
> > /*
> > * pr_debug() and friends are globally enabled or modules have selectively
> > * enabled them.
> > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> > index 781781835094..9283f2866415 100644
> > --- a/lib/dynamic_debug.c
> > +++ b/lib/dynamic_debug.c
> > @@ -660,6 +660,30 @@ static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
> >
> > #define CLASSMAP_BITMASK(width) ((1UL << (width)) - 1)
> >
> > +static void ddebug_class_param_clamp_input(unsigned long *inrep, const struct kernel_param *kp)
> > +{
> > + const struct ddebug_class_param *dcp = kp->arg;
> > + const struct ddebug_class_map *map = dcp->map;
> > +
> > + switch (map->map_type) {
> > + case DD_CLASS_TYPE_DISJOINT_BITS:
> > + /* expect bits. mask and warn if too many */
> > + if (*inrep & ~CLASSMAP_BITMASK(map->length)) {
> > + pr_warn("%s: input: 0x%lx exceeds mask: 0x%lx, masking\n",
> > + KP_NAME(kp), *inrep, CLASSMAP_BITMASK(map->length));
> > + *inrep &= CLASSMAP_BITMASK(map->length);
> > + }
> > + break;
> > + case DD_CLASS_TYPE_LEVEL_NUM:
> > + /* input is bitpos, of highest verbosity to be enabled */
> > + if (*inrep > map->length) {
> > + pr_warn("%s: level:%ld exceeds max:%d, clamping\n",
> > + KP_NAME(kp), *inrep, map->length);
> > + *inrep = map->length;
> > + }
> > + break;
> > + }
> > +}
> > static int param_set_dyndbg_module_classes(const char *instr,
> > const struct kernel_param *kp,
> > const char *modnm)
> > @@ -678,26 +702,15 @@ static int param_set_dyndbg_module_classes(const char *instr,
> > pr_err("expecting numeric input, not: %s > %s\n", instr, KP_NAME(kp));
> > return -EINVAL;
> > }
> > + ddebug_class_param_clamp_input(&inrep, kp);
> >
> > switch (map->map_type) {
> > case DD_CLASS_TYPE_DISJOINT_BITS:
> > - /* expect bits. mask and warn if too many */
> > - if (inrep & ~CLASSMAP_BITMASK(map->length)) {
> > - pr_warn("%s: input: 0x%lx exceeds mask: 0x%lx, masking\n",
> > - KP_NAME(kp), inrep, CLASSMAP_BITMASK(map->length));
> > - inrep &= CLASSMAP_BITMASK(map->length);
> > - }
> > v2pr_info("bits:0x%lx > %s.%s\n", inrep, modnm ?: "*", KP_NAME(kp));
> > totct += ddebug_apply_class_bitmap(dcp, &inrep, *dcp->bits, modnm);
> > *dcp->bits = inrep;
> > break;
> > case DD_CLASS_TYPE_LEVEL_NUM:
> > - /* input is bitpos, of highest verbosity to be enabled */
> > - if (inrep > map->length) {
> > - pr_warn("%s: level:%ld exceeds max:%d, clamping\n",
> > - KP_NAME(kp), inrep, map->length);
> > - inrep = map->length;
> > - }
> > old_bits = CLASSMAP_BITMASK(*dcp->lvl);
> > new_bits = CLASSMAP_BITMASK(inrep);
> > v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, KP_NAME(kp));
> > @@ -1163,15 +1176,24 @@ static const struct proc_ops proc_fops = {
> > static void ddebug_sync_classbits(const struct kernel_param *kp, const char *modname)
> > {
> > const struct ddebug_class_param *dcp = kp->arg;
> > + unsigned long new_bits;
> >
> > - /* 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);
> > + ddebug_class_param_clamp_input(dcp->bits, kp);
> > +
> > + switch (dcp->map->map_type) {
> > + case DD_CLASS_TYPE_DISJOINT_BITS:
> > + v2pr_info(" %s: classbits: 0x%lx\n", KP_NAME(kp), *dcp->bits);
> > + ddebug_apply_class_bitmap(dcp, dcp->bits, 0UL, modname);
> > + break;
> > + case DD_CLASS_TYPE_LEVEL_NUM:
> > + new_bits = CLASSMAP_BITMASK(*dcp->lvl);
> > + v2pr_info(" %s: lvl:%ld bits:0x%lx\n", KP_NAME(kp), *dcp->lvl, new_bits);
> > + ddebug_apply_class_bitmap(dcp, &new_bits, 0UL, modname);
> > + break;
> > + default:
> > + pr_err("bad map type %d\n", dcp->map->map_type);
> > + return;
> > }
> > - /* 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);
>
> Hi Jim,
>
> We lost the double call with ~0/0, is it normal?
Good catch,
I thought so, since it guarantees the pr_debugs' state to
comport with sysfs settings on modprobe.
I will review.
>
> Thanks a lot for your work,
> Louis Chauvet
>
> > }
> >
> > static void ddebug_match_apply_kparam(const struct kernel_param *kp,
> > diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
> > index 5cfc156ca4bb..32a9d49a7a3b 100644
> > --- a/lib/test_dynamic_debug.c
> > +++ b/lib/test_dynamic_debug.c
> > @@ -1,6 +1,7 @@
> > // SPDX-License-Identifier: GPL-2.0-only
> > /*
> > - * Kernel module for testing dynamic_debug
> > + * Kernel module to test/demonstrate dynamic_debug features,
> > + * particularly classmaps and their support for subsystems like DRM.
> > *
> > * Authors:
> > * Jim Cromie <jim.cromie@...il.com>
> > @@ -43,36 +44,21 @@ module_param_cb(do_prints, ¶m_ops_do_prints, NULL, 0600);
> >
> > #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, ¶m_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.
> > + * Demonstrate/test both types of classmaps, each 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.
> > + * Pair the 6 parts by type, to show the pattern of repetition and
> > + * change within each.
> > *
> > - * 1st, dyndbg expects a client-provided enum-type as source of
> > - * category/classid truth. DRM has DRM_UT_<CORE,DRIVER,KMS,etc>.
> > + * 1st, dyndbg classmaps follows drm.debug convention, and expects a
> > + * client-provided enum-type as source of category/classid truth. DRM
> > + * gives 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
> > + * Declare the 2 enums now.
> > */
> >
> > /* numeric input, independent bits */
> > @@ -91,12 +77,15 @@ enum cat_disjoint_bits {
> > /* numeric verbosity, V2 > V1 related */
> > enum cat_level_num { V0 = 16, V1, V2, V3, V4, V5, V6, V7 };
> >
> > -/* recapitulate DRM's parent(drm.ko) <-- _submod(drivers,helpers) */
> > +/*
> > + * use/demonstrate multi-module-group classmaps, as for DRM
> > + */
> > #if !defined(TEST_DYNAMIC_DEBUG_SUBMOD)
> > /*
> > - * 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.
> > + * For module-groups of 1+, define classmaps with names (stringified
> > + * enum-symbols) copied from above. 1-to-1 mapping is recommended.
> > + * The classmap is exported, so that other modules in the group can
> > + * link to it and control their prdbgs.
> > */
> >
> > DYNDBG_CLASSMAP_DEFINE(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS,
> > @@ -116,11 +105,12 @@ 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
> > + * for use-cases that want it, provide a sysfs-param to set the
> > + * classes in the classmap. It is at this interface where the
> > + * "v3>v2" property is applied to DD_CLASS_TYPE_LEVEL_NUM inputs.
> > */
> > -
> > -DYNDBG_CLASSMAP_PARAM(disjoint_bits, p);
> > -DYNDBG_CLASSMAP_PARAM(level_num, p);
> > +DYNDBG_CLASSMAP_PARAM(p_disjoint_bits, map_disjoint_bits, p);
> > +DYNDBG_CLASSMAP_PARAM(p_level_num, map_level_num, p);
> >
> > #ifdef FORCE_CLASSID_CONFLICT_MODPROBE
> > /*
> > @@ -131,12 +121,10 @@ DYNDBG_CLASSMAP_DEFINE(classid_range_conflict, 0, D2_CORE + 1, "D3_CORE");
> > #endif
> >
> > #else /* TEST_DYNAMIC_DEBUG_SUBMOD */
> > -
> > /*
> > - * in submod/drm-drivers, use the classmaps defined in top/parent
> > - * module above.
> > + * the +1 members of a multi-module group refer to the classmap
> > + * DEFINEd (and exported) above.
> > */
> > -
> > DYNDBG_CLASSMAP_USE(map_disjoint_bits);
> > DYNDBG_CLASSMAP_USE(map_level_num);
> >
> > @@ -211,6 +199,7 @@ static void __exit test_dynamic_debug_exit(void)
> > module_init(test_dynamic_debug_init);
> > module_exit(test_dynamic_debug_exit);
> >
> > +MODULE_DESCRIPTION("test/demonstrate dynamic-debug features");
> > MODULE_AUTHOR("Jim Cromie <jim.cromie@...il.com>");
> > MODULE_DESCRIPTION("Kernel module for testing dynamic_debug");
> > MODULE_LICENSE("GPL");
> > diff --git a/lib/test_dynamic_debug_submod.c b/lib/test_dynamic_debug_submod.c
> > index 9a893402ce1a..0d15f3ffe466 100644
> > --- a/lib/test_dynamic_debug_submod.c
> > +++ b/lib/test_dynamic_debug_submod.c
> > @@ -1,6 +1,9 @@
> > // SPDX-License-Identifier: GPL-2.0
> > /*
> > - * Kernel module for testing dynamic_debug
> > + * Kernel module to test/demonstrate dynamic_debug features,
> > + * particularly classmaps and their support for subsystems, like DRM,
> > + * which defines its drm_debug classmap in drm module, and uses it in
> > + * helpers & drivers.
> > *
> > * Authors:
> > * Jim Cromie <jim.cromie@...il.com>
> > @@ -8,3 +11,7 @@
> >
> > #define TEST_DYNAMIC_DEBUG_SUBMOD
> > #include "test_dynamic_debug.c"
> > +
> > +MODULE_DESCRIPTION("test/demonstrate dynamic-debug subsystem support");
> > +MODULE_AUTHOR("Jim Cromie <jim.cromie@...il.com>");
> > +MODULE_LICENSE("GPL");
>
> --
> Louis Chauvet, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
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