[PATCH 6/7] dyndbg: clone DECLARE_DYNDBG_CLASSMAP to REFERENCE_DYNDBG_CLASSMAP

[Jim Cromie]

DECLARE_DYNDBG_CLASSMAPs job is to allow modules to declare the debug
classes/categories they want dyndbg to >control.  Its args name the
class-names, and the sysfs interface style (usually a class-bitmap).
A separate module_param_cb wires the sysfs node to the classmap.

In DRM, multiple modules declare identical DRM_UT_* classmaps, so that
they are modified across those modules in a coordinated way, by either
explicit class DRM_UT_* queries to >control, or by writes to drm.debug
(/sys/module/drm/parameters/debug).

This coordination-by-identical-declarations is weird, so this patch
splits the macro into DECLARE and REFERENCE (USE?) flavors.  This
distinction improves the api; DECLARE is used once to specify the
classmap, and multiple users REFERENCE the single declaration
explicitly.

Currently the latter just reuses the former, and still needs all the
same args, but that can be tuned later; the DECLARE can initialize the
(extern/global) struct classmap, and REFERENCE can, well reference
that struct.

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
RFC: s/REFERENCE_/USE_/ ??
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c |  2 +-
 drivers/gpu/drm/display/drm_dp_helper.c |  2 +-
 drivers/gpu/drm/drm_crtc_helper.c       |  2 +-
 drivers/gpu/drm/i915/i915_params.c      |  2 +-
 drivers/gpu/drm/nouveau/nouveau_drm.c   |  2 +-
 include/linux/dynamic_debug.h           | 10 ++++++++++
 6 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 3c9fecdd6b2f..5c733d96fe4c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -188,7 +188,7 @@ int amdgpu_vcnfw_log;
 
 static void amdgpu_drv_delayed_reset_work_handler(struct work_struct *work);
 
-DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
+REFERENCE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
 			"DRM_UT_DRIVER",
 			"DRM_UT_KMS",
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 16565a0a5da6..1f20c1e721a4 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -41,7 +41,7 @@
 
 #include "drm_dp_helper_internal.h"
 
-DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
+REFERENCE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
 			"DRM_UT_DRIVER",
 			"DRM_UT_KMS",
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 7d86020b5244..4675c95c90b4 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -51,7 +51,7 @@
 
 #include "drm_crtc_helper_internal.h"
 
-DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
+REFERENCE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
 			"DRM_UT_DRIVER",
 			"DRM_UT_KMS",
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index d1e4d528cb17..14ebbbf53821 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -29,7 +29,7 @@
 #include "i915_params.h"
 #include "i915_drv.h"
 
-DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
+REFERENCE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
 			"DRM_UT_DRIVER",
 			"DRM_UT_KMS",
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index fd99ec0f4257..b943bf2a36fe 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -71,7 +71,7 @@
 #include "nouveau_svm.h"
 #include "nouveau_dmem.h"
 
-DECLARE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
+REFERENCE_DYNDBG_CLASSMAP(drm_debug_classes, DD_CLASS_TYPE_DISJOINT_BITS, 0,
 			"DRM_UT_CORE",
 			"DRM_UT_DRIVER",
 			"DRM_UT_KMS",
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 41682278d2e8..76430bac7f79 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -111,6 +111,16 @@ struct ddebug_class_map {
 #define NUM_TYPE_ARGS(eltype, ...)				\
         (sizeof((eltype[]){__VA_ARGS__}) / sizeof(eltype))
 
+/*
+ * refer to the classmap instantiated once, by the macro above.  This
+ * distinguishes the multiple users of drm.debug from the single
+ * definition, allowing them to specialize.  ATM its a pass-thru, but
+ * it should help regularize the admittedly wierd sharing by identical
+ * definitions.
+ */
+#define REFERENCE_DYNDBG_CLASSMAP(_var, _maptype, _base, ...)		\
+	DECLARE_DYNDBG_CLASSMAP(_var, _maptype, _base, __VA_ARGS__)
+
 /* encapsulate linker provided built-in (or module) dyndbg data */
 struct _ddebug_info {
 	struct _ddebug *descs;
-- 
2.38.1