[PATCH v2 05/27] dyndbg: add exclusive class_id to pr_debug callsites

[Jim Cromie <jim.cromie@xxxxxxxxx>]

DRM issues ~10 exclusive categories of debug messages; to represent
this directly in dyndbg, add a new field: struct _ddebug.class_id:5.

We only need 4 bits for drm, and with that reserved, we have 2 to
spare on 32 bit builds; lets take one extra (5 bits total), and keep a
spare bit.  32 classes-per-bitmap is a practical usability limit
anyway with a bitmap interface:

  #> echo 0x012345678 > /sys/module/drm/parameters/debug

All existing callsites are initialized with _DPRINTK_CLASS_DFLT, which
is 2^5-1.  This reserves 0-30 for use in new categorized/class'd
pr_debugs, which fits perfectly with natural enums (ints: 0..N).

To achieve this, DEFINE_DYNAMIC_DEBUG_METADATA_CLS(cls,...) is added,
and DEFINE_DYNAMIC_DEBUG_METADATA is altered to call it with the
default.  The factory macro chain between there and pr_debug is
adjusted similarly.

No behavior change.

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
 include/linux/dynamic_debug.h | 54 ++++++++++++++++++++++++++---------
 1 file changed, 41 insertions(+), 13 deletions(-)

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index dd20e825c36f..39550fefcf0f 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -6,6 +6,8 @@
 #include <linux/jump_label.h>
 #endif
 
+#include <linux/build_bug.h>
+
 /*
  * An instance of this structure is created in a special
  * ELF section at every dynamic debug callsite.  At runtime,
@@ -21,6 +23,9 @@ struct _ddebug {
 	const char *filename;
 	const char *format;
 	unsigned int lineno:18;
+#define CLS_BITS 5
+	unsigned int class_id:CLS_BITS;
+#define _DPRINTK_CLASS_DFLT		((1 << CLS_BITS) - 1)
 	/*
 	 * The flags field controls the behaviour at the callsite.
 	 * The bits here are changed dynamically when the user
@@ -84,7 +89,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 			 const struct ib_device *ibdev,
 			 const char *fmt, ...);
 
-#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)		\
+#define DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, cls, fmt)	\
 	static struct _ddebug  __aligned(8)			\
 	__section("__dyndbg") name = {				\
 		.modname = KBUILD_MODNAME,			\
@@ -93,8 +98,14 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 		.format = (fmt),				\
 		.lineno = __LINE__,				\
 		.flags = _DPRINTK_FLAGS_DEFAULT,		\
+		.class_id = cls,				\
 		_DPRINTK_KEY_INIT				\
-	}
+	};							\
+	BUILD_BUG_ON_MSG(cls > _DPRINTK_CLASS_DFLT,		\
+			 "classid value overflow")
+
+#define DEFINE_DYNAMIC_DEBUG_METADATA(name, fmt)		\
+	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(name, _DPRINTK_CLASS_DFLT, fmt)
 
 #ifdef CONFIG_JUMP_LABEL
 
@@ -125,18 +136,26 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
 
 #endif /* CONFIG_JUMP_LABEL */
 
-#define __dynamic_func_call(id, fmt, func, ...) do {	\
-	DEFINE_DYNAMIC_DEBUG_METADATA(id, fmt);		\
-	if (DYNAMIC_DEBUG_BRANCH(id))			\
-		func(&id, ##__VA_ARGS__);		\
+#define __dynamic_func_call_cls(id, cls, fmt, func, ...) do {	\
+	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);	\
+	if (DYNAMIC_DEBUG_BRANCH(id))				\
+		func(&id, ##__VA_ARGS__);			\
 } while (0)
 
-#define __dynamic_func_call_no_desc(id, fmt, func, ...) do {	\
-	DEFINE_DYNAMIC_DEBUG_METADATA(id, fmt);			\
-	if (DYNAMIC_DEBUG_BRANCH(id))				\
-		func(__VA_ARGS__);				\
+#define __dynamic_func_call_no_desc_cls(id, cls, fmt, func, ...) do {	\
+	DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt);		\
+	if (DYNAMIC_DEBUG_BRANCH(id))					\
+		func(__VA_ARGS__);					\
 } while (0)
 
+#define __dynamic_func_call(id, fmt, func, ...)				\
+	__dynamic_func_call_cls(id, _DPRINTK_CLASS_DFLT,		\
+				fmt, func, ##__VA_ARGS__)
+
+#define __dynamic_func_call_no_desc(id, fmt, func, ...)			\
+	__dynamic_func_call_no_desc_cls(id, _DPRINTK_CLASS_DFLT,	\
+					fmt, func, ##__VA_ARGS__)
+
 /*
  * "Factory macro" for generating a call to func, guarded by a
  * DYNAMIC_DEBUG_BRANCH. The dynamic debug descriptor will be
@@ -145,15 +164,24 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
  * the varargs. Note that fmt is repeated in invocations of this
  * macro.
  */
+#define _dynamic_func_call_cls(cls, fmt, func, ...)			\
+	__dynamic_func_call_cls(__UNIQUE_ID(ddebug), cls, fmt, func, ##__VA_ARGS__)
 #define _dynamic_func_call(fmt, func, ...)				\
-	__dynamic_func_call(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
+	_dynamic_func_call_cls(_DPRINTK_CLASS_DFLT, fmt, func, ##__VA_ARGS__)
+
 /*
  * A variant that does the same, except that the descriptor is not
  * passed as the first argument to the function; it is only called
  * with precisely the macro's varargs.
  */
-#define _dynamic_func_call_no_desc(fmt, func, ...)	\
-	__dynamic_func_call_no_desc(__UNIQUE_ID(ddebug), fmt, func, ##__VA_ARGS__)
+#define _dynamic_func_call_no_desc_cls(fmt, cat, func, ...)		\
+	__dynamic_func_call_no_desc_cls(__UNIQUE_ID(ddebug), cat,	\
+					fmt, func, ##__VA_ARGS__)
+
+#define _dynamic_func_call_no_desc(fmt, func, ...)			\
+	__dynamic_func_call_no_desc_cls(__UNIQUE_ID(ddebug),		\
+					_DPRINTK_CLASS_DFLT,	\
+					fmt, func, ##__VA_ARGS__)
 
 #define dynamic_pr_debug(fmt, ...)				\
 	_dynamic_func_call(fmt,	__dynamic_pr_debug,		\
-- 
2.35.3