wimax: debug macros and debug settings for the WiMAX stack

This file contains a simple debug framework that is used in the stack;
it allows the debug level to be controlled at compile-time (so the
debug code is optimized out) and at run-time (for what wasn't compiled
out).

This is eventually going to be moved to use dynamic_printk(). Just
need to find time to do it.

Signed-off-by: Inaky Perez-Gonzalez <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

include/linux/wimax/debug.h

···
+/*
+ * Linux WiMAX
+ * Collection of tools to manage debug operations.
+ *
+ *
+ * Copyright (C) 2005-2007 Intel Corporation
+ * Inaky Perez-Gonzalez <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ *
+ * Don't #include this file directly, read on!
+ *
+ *
+ * EXECUTING DEBUGGING ACTIONS OR NOT
+ *
+ * The main thing this framework provides is decission power to take a
+ * debug action (like printing a message) if the current debug level
+ * allows it.
+ *
+ * The decission power is at two levels: at compile-time (what does
+ * not make it is compiled out) and at run-time. The run-time
+ * selection is done per-submodule (as they are declared by the user
+ * of the framework).
+ *
+ * A call to d_test(L) (L being the target debug level) returns true
+ * if the action should be taken because the current debug levels
+ * allow it (both compile and run time).
+ *
+ * It follows that a call to d_test() that can be determined to be
+ * always false at compile time will get the code depending on it
+ * compiled out by optimization.
+ *
+ *
+ * DEBUG LEVELS
+ *
+ * It is up to the caller to define how much a debugging level is.
+ *
+ * Convention sets 0 as "no debug" (so an action marked as debug level 0
+ * will always be taken). The increasing debug levels are used for
+ * increased verbosity.
+ *
+ *
+ * USAGE
+ *
+ * Group the code in modules and submodules inside each module [which
+ * in most cases maps to Linux modules and .c files that compose
+ * those].
+ *
+ *
+ * For each module, there is:
+ *
+ *  - a MODULENAME (single word, legal C identifier)
+ *
+ *  - a debug-levels.h header file that declares the list of
+ *    submodules and that is included by all .c files that use
+ *    the debugging tools. The file name can be anything.
+ *
+ *  - some (optional) .c code to manipulate the runtime debug levels
+ *    through debugfs.
+ *
+ * The debug-levels.h file would look like:
+ *
+ *     #ifndef __debug_levels__h__
+ *     #define __debug_levels__h__
+ *
+ *     #define D_MODULENAME modulename
+ *     #define D_MASTER 10
+ *
+ *     #include <linux/wimax/debug.h>
+ *
+ *     enum d_module {
+ *             D_SUBMODULE_DECLARE(submodule_1),
+ *             D_SUBMODULE_DECLARE(submodule_2),
+ *             ...
+ *             D_SUBMODULE_DECLARE(submodule_N)
+ *     };
+ *
+ *     #endif
+ *
+ * D_MASTER is the maximum compile-time debug level; any debug actions
+ * above this will be out. D_MODULENAME is the module name (legal C
+ * identifier), which has to be unique for each module (to avoid
+ * namespace collisions during linkage). Note those #defines need to
+ * be done before #including debug.h
+ *
+ * We declare N different submodules whose debug level can be
+ * independently controlled during runtime.
+ *
+ * In a .c file of the module (and only in one of them), define the
+ * following code:
+ *
+ *     struct d_level D_LEVEL[] = {
+ *             D_SUBMODULE_DEFINE(submodule_1),
+ *             D_SUBMODULE_DEFINE(submodule_2),
+ *             ...
+ *             D_SUBMODULE_DEFINE(submodule_N),
+ *     };
+ *     size_t D_LEVEL_SIZE = ARRAY_SIZE(D_LEVEL);
+ *
+ * Externs for d_level_MODULENAME and d_level_size_MODULENAME are used
+ * and declared in this file using the D_LEVEL and D_LEVEL_SIZE macros
+ * #defined also in this file.
+ *
+ * To manipulate from user space the levels, create a debugfs dentry
+ * and then register each submodule with:
+ *
+ *     result = d_level_register_debugfs("PREFIX_", submodule_X, parent);
+ *     if (result < 0)
+ *            goto error;
+ *
+ * Where PREFIX_ is a name of your chosing. This will create debugfs
+ * file with a single numeric value that can be use to tweak it. To
+ * remove the entires, just use debugfs_remove_recursive() on 'parent'.
+ *
+ * NOTE: remember that even if this will show attached to some
+ *     particular instance of a device, the settings are *global*.
+ *
+ *
+ * On each submodule (for example, .c files), the debug infrastructure
+ * should be included like this:
+ *
+ *     #define D_SUBMODULE submodule_x     // matches one in debug-levels.h
+ *     #include "debug-levels.h"
+ *
+ * after #including all your include files.
+ *
+ *
+ * Now you can use the d_*() macros below [d_test(), d_fnstart(),
+ * d_fnend(), d_printf(), d_dump()].
+ *
+ * If their debug level is greater than D_MASTER, they will be
+ * compiled out.
+ *
+ * If their debug level is lower or equal than D_MASTER but greater
+ * than the current debug level of their submodule, they'll be
+ * ignored.
+ *
+ * Otherwise, the action will be performed.
+ */
+#ifndef __debug__h__
+#define __debug__h__
+
+#include <linux/types.h>
+#include <linux/device.h>
+
+
+/* Backend stuff */
+
+/*
+ * Debug backend: generate a message header from a 'struct device'
+ *
+ * @head: buffer where to place the header
+ * @head_size: length of @head
+ * @dev: pointer to device used to generate a header from. If NULL,
+ *     an empty ("") header is generated.
+ */
+static inline
+void __d_head(char *head, size_t head_size,
+	      struct device *dev)
+{
+	if (dev == NULL)
+		head[0] = 0;
+	else if ((unsigned long)dev < 4096) {
+		printk(KERN_ERR "E: Corrupt dev %p\n", dev);
+		WARN_ON(1);
+	} else
+		snprintf(head, head_size, "%s %s: ",
+			 dev_driver_string(dev), dev->bus_id);
+}
+
+
+/*
+ * Debug backend: log some message if debugging is enabled
+ *
+ * @l: intended debug level
+ * @tag: tag to prefix the message with
+ * @dev: 'struct device' associated to this message
+ * @f: printf-like format and arguments
+ *
+ * Note this is optimized out if it doesn't pass the compile-time
+ * check; however, it is *always* compiled. This is useful to make
+ * sure the printf-like formats and variables are always checked and
+ * they don't get bit rot if you have all the debugging disabled.
+ */
+#define _d_printf(l, tag, dev, f, a...)					\
+do {									\
+	char head[64];							\
+	if (!d_test(l))							\
+		break;							\
+	__d_head(head, sizeof(head), dev);				\
+	printk(KERN_ERR "%s%s%s: " f, head, __func__, tag, ##a);	\
+} while (0)
+
+
+/*
+ * CPP sintatic sugar to generate A_B like symbol names when one of
+ * the arguments is a a preprocessor #define.
+ */
+#define __D_PASTE__(varname, modulename) varname##_##modulename
+#define __D_PASTE(varname, modulename) (__D_PASTE__(varname, modulename))
+#define _D_SUBMODULE_INDEX(_name) (D_SUBMODULE_DECLARE(_name))
+
+
+/*
+ * Store a submodule's runtime debug level and name
+ */
+struct d_level {
+	u8 level;
+	const char *name;
+};
+
+
+/*
+ * List of available submodules and their debug levels
+ *
+ * We call them d_level_MODULENAME and d_level_size_MODULENAME; the
+ * macros D_LEVEL and D_LEVEL_SIZE contain the name already for
+ * convenience.
+ *
+ * This array and the size are defined on some .c file that is part of
+ * the current module.
+ */
+#define D_LEVEL __D_PASTE(d_level, D_MODULENAME)
+#define D_LEVEL_SIZE __D_PASTE(d_level_size, D_MODULENAME)
+
+extern struct d_level D_LEVEL[];
+extern size_t D_LEVEL_SIZE;
+
+
+/*
+ * Frontend stuff
+ *
+ *
+ * Stuff you need to declare prior to using the actual "debug" actions
+ * (defined below).
+ */
+
+#ifndef D_MODULENAME
+#error D_MODULENAME is not defined in your debug-levels.h file
+/**
+ * D_MODULE - Name of the current module
+ *
+ * #define in your module's debug-levels.h, making sure it is
+ * unique. This has to be a legal C identifier.
+ */
+#define D_MODULENAME undefined_modulename
+#endif
+
+
+#ifndef D_MASTER
+#warning D_MASTER not defined, but debug.h included! [see docs]
+/**
+ * D_MASTER - Compile time maximum debug level
+ *
+ * #define in your debug-levels.h file to the maximum debug level the
+ * runtime code will be allowed to have. This allows you to provide a
+ * main knob.
+ *
+ * Anything above that level will be optimized out of the compile.
+ *
+ * Defaults to zero (no debug code compiled in).
+ *
+ * Maximum one definition per module (at the debug-levels.h file).
+ */
+#define D_MASTER 0
+#endif
+
+#ifndef D_SUBMODULE
+#error D_SUBMODULE not defined, but debug.h included! [see docs]
+/**
+ * D_SUBMODULE - Name of the current submodule
+ *
+ * #define in your submodule .c file before #including debug-levels.h
+ * to the name of the current submodule as previously declared and
+ * defined with D_SUBMODULE_DECLARE() (in your module's
+ * debug-levels.h) and D_SUBMODULE_DEFINE().
+ *
+ * This is used to provide runtime-control over the debug levels.
+ *
+ * Maximum one per .c file! Can be shared among different .c files
+ * (meaning they belong to the same submodule categorization).
+ */
+#define D_SUBMODULE undefined_module
+#endif
+
+
+/**
+ * D_SUBMODULE_DECLARE - Declare a submodule for runtime debug level control
+ *
+ * @_name: name of the submodule, restricted to the chars that make up a
+ *     valid C identifier ([a-zA-Z0-9_]).
+ *
+ * Declare in the module's debug-levels.h header file as:
+ *
+ * enum d_module {
+ *         D_SUBMODULE_DECLARE(submodule_1),
+ *         D_SUBMODULE_DECLARE(submodule_2),
+ *         D_SUBMODULE_DECLARE(submodule_3),
+ * };
+ *
+ * Some corresponding .c file needs to have a matching
+ * D_SUBMODULE_DEFINE().
+ */
+#define D_SUBMODULE_DECLARE(_name) __D_SUBMODULE_##_name
+
+
+/**
+ * D_SUBMODULE_DEFINE - Define a submodule for runtime debug level control
+ *
+ * @_name: name of the submodule, restricted to the chars that make up a
+ *     valid C identifier ([a-zA-Z0-9_]).
+ *
+ * Use once per module (in some .c file) as:
+ *
+ * static
+ * struct d_level d_level_SUBMODULENAME[] = {
+ *         D_SUBMODULE_DEFINE(submodule_1),
+ *         D_SUBMODULE_DEFINE(submodule_2),
+ *         D_SUBMODULE_DEFINE(submodule_3),
+ * };
+ * size_t d_level_size_SUBDMODULENAME = ARRAY_SIZE(d_level_SUBDMODULENAME);
+ *
+ * Matching D_SUBMODULE_DECLARE()s have to be present in a
+ * debug-levels.h header file.
+ */
+#define D_SUBMODULE_DEFINE(_name)		\
+[__D_SUBMODULE_##_name] = {			\
+	.level = 0,				\
+	.name = #_name				\
+}
+
+
+
+/* The actual "debug" operations */
+
+
+/**
+ * d_test - Returns true if debugging should be enabled
+ *
+ * @l: intended debug level (unsigned)
+ *
+ * If the master debug switch is enabled and the current settings are
+ * higher or equal to the requested level, then debugging
+ * output/actions should be enabled.
+ *
+ * NOTE:
+ *
+ * This needs to be coded so that it can be evaluated in compile
+ * time; this is why the ugly BUG_ON() is placed in there, so the
+ * D_MASTER evaluation compiles all out if it is compile-time false.
+ */
+#define d_test(l)							\
+({									\
+	unsigned __l = l;	/* type enforcer */			\
+	(D_MASTER) >= __l						\
+	&& ({								\
+		BUG_ON(_D_SUBMODULE_INDEX(D_SUBMODULE) >= D_LEVEL_SIZE);\
+		D_LEVEL[_D_SUBMODULE_INDEX(D_SUBMODULE)].level >= __l;	\
+	});								\
+})
+
+
+/**
+ * d_fnstart - log message at function start if debugging enabled
+ *
+ * @l: intended debug level
+ * @_dev: 'struct device' pointer, NULL if none (for context)
+ * @f: printf-like format and arguments
+ */
+#define d_fnstart(l, _dev, f, a...) _d_printf(l, " FNSTART", _dev, f, ## a)
+
+
+/**
+ * d_fnend - log message at function end if debugging enabled
+ *
+ * @l: intended debug level
+ * @_dev: 'struct device' pointer, NULL if none (for context)
+ * @f: printf-like format and arguments
+ */
+#define d_fnend(l, _dev, f, a...) _d_printf(l, " FNEND", _dev, f, ## a)
+
+
+/**
+ * d_printf - log message if debugging enabled
+ *
+ * @l: intended debug level
+ * @_dev: 'struct device' pointer, NULL if none (for context)
+ * @f: printf-like format and arguments
+ */
+#define d_printf(l, _dev, f, a...) _d_printf(l, "", _dev, f, ## a)
+
+
+/**
+ * d_dump - log buffer hex dump if debugging enabled
+ *
+ * @l: intended debug level
+ * @_dev: 'struct device' pointer, NULL if none (for context)
+ * @f: printf-like format and arguments
+ */
+#define d_dump(l, dev, ptr, size)			\
+do {							\
+	char head[64];					\
+	if (!d_test(l))					\
+		break;					\
+	__d_head(head, sizeof(head), dev);		\
+	print_hex_dump(KERN_ERR, head, 0, 16, 1,	\
+		       ((void *) ptr), (size), 0);	\
+} while (0)
+
+
+/**
+ * Export a submodule's debug level over debugfs as PREFIXSUBMODULE
+ *
+ * @prefix: string to prefix the name with
+ * @submodule: name of submodule (not a string, just the name)
+ * @dentry: debugfs parent dentry
+ *
+ * Returns: 0 if ok, < 0 errno on error.
+ *
+ * For removing, just use debugfs_remove_recursive() on the parent.
+ */
+#define d_level_register_debugfs(prefix, name, parent)			\
+({									\
+	int rc;								\
+	struct dentry *fd;						\
+	struct dentry *verify_parent_type = parent;			\
+	fd = debugfs_create_u8(						\
+		prefix #name, 0600, verify_parent_type,			\
+		&(D_LEVEL[__D_SUBMODULE_ ## name].level));		\
+	rc = PTR_ERR(fd);						\
+	if (IS_ERR(fd) && rc != -ENODEV)				\
+		printk(KERN_ERR "%s: Can't create debugfs entry %s: "	\
+		       "%d\n", __func__, prefix #name, rc);		\
+	else								\
+		rc = 0;							\
+	rc;								\
+})
+
+
+#endif /* #ifndef __debug__h__ */

net/wimax/debug-levels.h

···
+/*
+ * Linux WiMAX Stack
+ * Debug levels control file for the wimax module
+ *
+ *
+ * Copyright (C) 2007-2008 Intel Corporation <[e-mail]>
+ * Inaky Perez-Gonzalez <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+#ifndef __debug_levels__h__
+#define __debug_levels__h__
+
+/* Maximum compile and run time debug level for all submodules */
+#define D_MODULENAME wimax
+#define D_MASTER CONFIG_WIMAX_DEBUG_LEVEL
+
+#include <linux/wimax/debug.h>
+
+/* List of all the enabled modules */
+enum d_module {
+	D_SUBMODULE_DECLARE(debugfs),
+	D_SUBMODULE_DECLARE(id_table),
+	D_SUBMODULE_DECLARE(op_msg),
+	D_SUBMODULE_DECLARE(op_reset),
+	D_SUBMODULE_DECLARE(op_rfkill),
+	D_SUBMODULE_DECLARE(stack),
+};
+
+#endif /* #ifndef __debug_levels__h__ */