[PATCH v2 22/59] dyndbg-API: promote DYNAMIC_DEBUG_CLASSMAP_PARAM to API
Louis Chauvet
louis.chauvet at bootlin.com
Mon Mar 24 15:18:11 UTC 2025
Le 20/03/2025 à 19:52, Jim Cromie a écrit :
> move the DYNAMIC_DEBUG_CLASSMAP_PARAM macro from test-dynamic-debug.c into
> the header, and refine it, by distinguishing the 2 use cases:
>
> 1.DYNAMIC_DEBUG_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.DYNAMIC_DEBUG_CLASSMAP_PARAM
> new user (test_dynamic_debug) doesn't need to share state,
> decls a static long unsigned int to store the bitvec.
>
> __DYNAMIC_DEBUG_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.
>
> cc: linux-doc at vger.kernel.org
> Signed-off-by: Jim Cromie <jim.cromie at gmail.com>
> ---
>
> -v9
> - fixup drm-print.h add PARAM_REF forwarding macros
> with DYNAMIC_DEBUG_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 | 47 ++++++++++----------------
> lib/test_dynamic_debug_submod.c | 9 ++++-
> 4 files changed, 104 insertions(+), 50 deletions(-)
>
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index da2d677947ee..03a83a83b621 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -212,6 +212,44 @@ struct _ddebug_class_param {
> const struct _ddebug_class_map *map;
> };
>
> +/**
> + * DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _var, _flags) \
> + static unsigned long _name##_bvec; \
> + __DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _name##_bvec, _var, _flags)
> +
> +/**
> + * DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_CLASSMAP_PARAM_REF(_name, _bits, _var, _flags) \
> + __DYNAMIC_DEBUG_CLASSMAP_PARAM(_name, _bits, _var, _flags)
> +
> +#define __DYNAMIC_DEBUG_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 e84b6677e94d..3c9fb8324ad6 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -661,6 +661,30 @@ 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)
> @@ -679,26 +703,15 @@ 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));
> @@ -1176,15 +1189,24 @@ 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);
> }
>
> 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 4a3d2612ef60..78cf5420770a 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 at gmail.com>
> @@ -62,24 +63,6 @@ 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 DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_CLASSMAP_PARAM(_model, _flags) \
> - DYNAMIC_DEBUG_CLASSMAP_PARAM_(_model, _flags, ~0)
> -#else
> -#define DYNAMIC_DEBUG_CLASSMAP_PARAM(_model, _flags) \
> - DYNAMIC_DEBUG_CLASSMAP_PARAM_(_model, _flags, 0)
> -#endif
> -
> /*
> * Demonstrate/test DISJOINT & LEVEL typed classmaps with a sys-param.
> *
> @@ -110,12 +93,15 @@ enum cat_disjoint_bits {
> /* numeric verbosity, V2 > V1 related. V0 is > D2_DRM_RES */
> enum cat_level_num { V0 = 16, V1, V2, V3, V4, V5, V6, V7 };
>
> -/* recapitulate DRM's multi-classmap setup */
> +/*
> + * 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.
> */
> DYNAMIC_DEBUG_CLASSMAP_DEFINE(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS,
> D2_CORE,
> @@ -134,11 +120,13 @@ DYNAMIC_DEBUG_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.
> */
>
> -DYNAMIC_DEBUG_CLASSMAP_PARAM(disjoint_bits, p);
> -DYNAMIC_DEBUG_CLASSMAP_PARAM(level_num, p);
> +DYNAMIC_DEBUG_CLASSMAP_PARAM(p_disjoint_bits, map_disjoint_bits, p);
> +DYNAMIC_DEBUG_CLASSMAP_PARAM(p_level_num, map_level_num, p);
>
> #ifdef FORCE_CLASSID_CONFLICT
> /*
> @@ -149,12 +137,10 @@ 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.
> */
> -
> DYNAMIC_DEBUG_CLASSMAP_USE(map_disjoint_bits);
> DYNAMIC_DEBUG_CLASSMAP_USE(map_level_num);
>
> @@ -229,6 +215,7 @@ 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");
I think this belongs to the patch introducing test_dynamic_debug_submod.c
> MODULE_AUTHOR("Jim Cromie <jim.cromie at gmail.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 672aabf40160..3adf3925fb86 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 at gmail.com>
> @@ -12,3 +15,7 @@
> */
> #define TEST_DYNAMIC_DEBUG_SUBMOD
> #include "test_dynamic_debug.c"
> +
> +MODULE_DESCRIPTION("test/demonstrate dynamic-debug subsystem support");
> +MODULE_AUTHOR("Jim Cromie <jim.cromie at gmail.com>");
> +MODULE_LICENSE("GPL");
I think this belongs to the patch introducing test_dynamic_debug_submod.c
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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