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    Subject[PATCH v7b 17/25] dyndbg-API: promote DYNDBG_CLASSMAP_PARAM to API
    Date
    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.

    Also clean up and improve comments in test-code, and add
    MODULE_DESCRIPTIONs.

    Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
    ---
    ---
    drivers/gpu/drm/drm_print.c | 8 ++---
    include/drm/drm_print.h | 6 ++--
    include/linux/dynamic_debug.h | 37 +++++++++++++++++++++-
    lib/test_dynamic_debug.c | 56 +++++++++++----------------------
    lib/test_dynamic_debug_submod.c | 9 +++++-
    5 files changed, 69 insertions(+), 47 deletions(-)

    diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
    index dabcfa0dd279..8f4b609353a5 100644
    --- a/drivers/gpu/drm/drm_print.c
    +++ b/drivers/gpu/drm/drm_print.c
    @@ -69,12 +69,8 @@ DRM_CLASSMAP_DEFINE(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS,
    "DRM_UT_DP",
    "DRM_UT_DRMRES");

    -static struct ddebug_class_param drm_debug_bitmap = {
    - .bits = &__drm_debug,
    - .flags = "p",
    - .map = &drm_debug_classes,
    -};
    -module_param_cb(debug, &param_ops_dyndbg_classes, &drm_debug_bitmap, 0600);
    +DRM_CLASSMAP_PARAM_REF(debug, __drm_debug, drm_debug_classes, p);
    +
    #endif

    void __drm_puts_coredump(struct drm_printer *p, const char *str)
    diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
    index 706afc97c79c..94d4f5500030 100644
    --- a/include/drm/drm_print.h
    +++ b/include/drm/drm_print.h
    @@ -322,11 +322,13 @@ enum drm_debug_category {
    };

    #ifdef CONFIG_DRM_USE_DYNAMIC_DEBUG
    -#define DRM_CLASSMAP_DEFINE(...) DYNDBG_CLASSMAP_DEFINE(__VA_ARGS__)
    -#define DRM_CLASSMAP_USE(name) DYNDBG_CLASSMAP_USE(name)
    +#define DRM_CLASSMAP_DEFINE(...) DYNDBG_CLASSMAP_DEFINE(__VA_ARGS__)
    +#define DRM_CLASSMAP_USE(name) DYNDBG_CLASSMAP_USE(name)
    +#define DRM_CLASSMAP_PARAM_REF(...) DYNDBG_CLASSMAP_PARAM_REF(__VA_ARGS__)
    #else
    #define DRM_CLASSMAP_DEFINE(...)
    #define DRM_CLASSMAP_USE(name)
    +#define DRM_CLASSMAP_PARAM_REF(...)
    #endif

    static inline bool drm_debug_enabled_raw(enum drm_debug_category category)
    diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
    index 1b027be2cdc4..f182f95caabb 100644
    --- a/include/linux/dynamic_debug.h
    +++ b/include/linux/dynamic_debug.h
    @@ -91,7 +91,7 @@ struct ddebug_class_map {
    * used to validate a "class FOO .." >control command on the module
    */
    #define DYNDBG_CLASSMAP_DEFINE(_var, _maptype, _base, ...) \
    - const char *_var##_classnames[] = { __VA_ARGS__ }; \
    + static const char *_var##_classnames[] = { __VA_ARGS__ }; \
    struct ddebug_class_map __aligned(8) __used \
    __section("__dyndbg_classes") _var = { \
    .mod = THIS_MODULE, \
    @@ -145,6 +145,41 @@ struct ddebug_class_param {
    const struct ddebug_class_map *map;
    };

    +/**
    + * DYNDBG_CLASSMAP_PARAM - wrap a dyndbg-classmap with a controlling sys-param
    + * @_name sysfs node name
    + * @_var name of the struct classmap var defining the controlled classes
    + * @_flags flags to be toggled, typically just 'p'
    + *
    + * Creates a sysfs-param to control the classes defined by the
    + * classmap. Keeps bits in a private/static
    + */
    +#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 dyndbg-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 struct classmap var defining the controlled classes
    + * @_flags flags to be toggled, typically just 'p'
    + *
    + * Creates a sysfs-param to control the classmap, keeping bitvec in user @_bits.
    + * This lets drm use __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, &param_ops_dyndbg_classes, \
    + &_name##_##_flags, 0600)
    +
    /*
    * pr_debug() and friends are globally enabled or modules have selectively
    * enabled them.
    diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
    index 23967071b60f..b3c6f90b9fe8 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@gmail.com>
    @@ -35,24 +36,8 @@ module_param_cb(do_prints, &param_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, &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.
    + * 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
    @@ -64,7 +49,7 @@ module_param_cb(do_prints, &param_ops_do_prints, NULL, 0600);
    * 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 all enums now, for different types
    */

    /* numeric input, independent bits */
    @@ -83,18 +68,15 @@ enum cat_disjoint_bits {
    /* numeric verbosity, V2 > V1 related */
    enum cat_level_num { V0 = 14, V1, V2, V3, V4, V5, V6, V7 };

    -/* named-symbolic input, independent bits */
    -enum cat_disjoint_names { LOW = 10, MID, HI };
    -
    -/* named-symbolic verbosity */
    -enum cat_level_names { L0 = 22, L1, L2, L3, L4, L5, L6, L7 };
    -
    -/* 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,
    D2_CORE,
    @@ -113,19 +95,18 @@ 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);

    #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);

    @@ -186,5 +167,6 @@ 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@gmail.com>");
    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@gmail.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@gmail.com>");
    +MODULE_LICENSE("GPL");
    --
    2.41.0
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