debug printk infrastructure -base patch

Signed-off-by Jason Baron <[email protected]>

---
 include/asm-generic/vmlinux.lds.h |   14 ++-
 include/linux/device.h            |   16 ++
 include/linux/dynamic_printk.h    |   44 +++++
 include/linux/kernel.h            |   16 ++
 include/linux/module.h            |    5 +
 kernel/module.c                   |   20 +++
 lib/Kconfig.debug                 |   46 +++++
 lib/Makefile                      |    2 +
 lib/dynamic_printk.c              |  327 +++++++++++++++++++++++++++++++++++++
 9 files changed, 489 insertions(+), 1 deletions(-)
 create mode 100644 include/linux/dynamic_printk.h
 create mode 100644 lib/dynamic_printk.c

include/asm-generic/vmlinux.lds.h +5 -0

index f054778..9516de4 100644
@@ -168,6 +168,18 @@
 		*(__ksymtab_strings)					\
 	}								\
 									\
+	/* dynamic printk sections: strings */				\
+	__verbose_strings : AT(ADDR(__verbose_strings) - LOAD_OFFSET) { \
+		*(__verbose_strings)					\
+	}								\
+									\

include/linux/device.h +6 -0

index 1a06026..8f3ca1f 100644
@@ -595,6 +595,22 @@ extern const char *dev_driver_string(struct device *dev);
 #ifdef DEBUG
 #define dev_dbg(dev, format, arg...)		\
 	dev_printk(KERN_DEBUG , dev , format , ## arg)
+#elif defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
+#define dev_dbg(dev, format, ...) do {				    	     \
+	static char bar[]						     \
+	__attribute__((section("__verbose_strings")))			     \
+	 = KBUILD_MODNAME;						     \
+	static struct mod_debug foobar					     \

include/linux/device.h +0 -0

 #else
 #define dev_dbg(dev, format, arg...)		\
 	({ if (0) dev_printk(KERN_DEBUG, dev, format, ##arg); 0; })

include/linux/dynamic_printk.h new file +34 -0

new file mode 100644
index 0000000..b1afef3
@@ -0,0 +1,44 @@
+#ifndef _DYNAMIC_PRINTK_H
+#define _DYNAMIC_PRINTK_H
+
+#ifdef __KERNEL__
+
+#include <linux/string.h>
+
+#define DYNAMIC_HASH_BITS 5
+#define FILE_TABLE_SIZE (1 << DYNAMIC_HASH_BITS)
+
+struct mod_debug {
+	char *modname;
+};
+
+void add_module(char *);
+int remove_module(char *);
+
+extern int dynamic_printk_enabled[];
+extern void dynamic_printk(char *, char *, ...);
+
+static inline unsigned long
+dynamic_partial_name_hash(unsigned long c, unsigned long prevhash)
+{
+        return (prevhash + (c << 4) + (c >> 4)) * 11;
+}
+
+
+static inline unsigned int
+dynamic_full_name_hash(const unsigned char *name, unsigned int len)
+{
+        unsigned long hash = 0;
+        while (len--)
+                hash = dynamic_partial_name_hash(*name++, hash);
+        return hash;

include/linux/kernel.h +6 -0

index cd6d02c..8acf1fc 100644
@@ -14,6 +14,7 @@
 #include <linux/compiler.h>
 #include <linux/bitops.h>
 #include <linux/log2.h>
+#include <linux/dynamic_printk.h>
 #include <asm/byteorder.h>
 #include <asm/bug.h>
 

@@ -292,6 +293,21 @@ extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
 /* If you are writing a driver, please use dev_dbg instead */
 #define pr_debug(fmt, arg...) \
 	printk(KERN_DEBUG fmt, ##arg)
+#elif defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
+#define pr_debug(fmt, ...) do { \
+	static char bar[]	           		   	   \
+	__attribute__((section("__verbose_strings")))		   \
+	 = KBUILD_MODNAME;					   \

include/linux/kernel.h +0 -0

 #else
 #define pr_debug(fmt, arg...) \
 	({ if (0) printk(KERN_DEBUG fmt, ##arg); 0; })

include/linux/module.h +5 -0

index 819c4e8..5536f2d 100644
@@ -16,6 +16,7 @@
 #include <linux/kobject.h>
 #include <linux/moduleparam.h>
 #include <linux/marker.h>
+#include <linux/dynamic_printk.h>
 #include <asm/local.h>
 
 #include <asm/module.h>

@@ -359,6 +360,10 @@ struct module
 	struct marker *markers;
 	unsigned int num_markers;
 #endif
+#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
+	struct mod_debug *verbose;
+	unsigned int num_verbose;
+#endif
 };
 #ifndef MODULE_ARCH_INIT
 #define MODULE_ARCH_INIT {}

kernel/module.c +1 -0

index 8d6cccc..2dd2ef6 100644
@@ -42,6 +42,7 @@
 #include <linux/string.h>
 #include <linux/mutex.h>
 #include <linux/unwind.h>
+#include <linux/dynamic_printk.h>
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
 #include <linux/license.h>

kernel/module.c +4 -0

+	struct mod_debug *iter;
 	struct module *mod;
 	long err = 0;
 	void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */

@@ -1993,6 +2000,9 @@ static struct module *load_module(void __user *umod,
 	markersindex = find_sec(hdr, sechdrs, secstrings, "__markers");
  	markersstringsindex = find_sec(hdr, sechdrs, secstrings,
 					"__markers_strings");
+	verboseindex = find_sec(hdr, sechdrs, secstrings, "__verbose");
+	verbosestringsindex = find_sec(hdr, sechdrs, secstrings,
+					"__verbose_strings");
 
 	/* Now do relocations. */
 	for (i = 1; i < hdr->e_shnum; i++) {

kernel/module.c +3 -0

+	mod->num_verbose =
+		sechdrs[verboseindex].sh_size / sizeof(*mod->verbose);
+#endif
 
         /* Find duplicate symbols */
 	err = verify_export_symbols(mod);

kernel/module.c +0 -0

 	err = module_finalize(hdr, sechdrs, mod);
 	if (err < 0)
 		goto cleanup;

lib/Kconfig.debug +35 -0

index 623ef24..a6f6d8f 100644
@@ -632,6 +632,52 @@ config FIREWIRE_OHCI_REMOTE_DMA
 
 	  If unsure, say N.
 
+config PRINTK_DEBUG
+	bool "Enable centralized debug printk() call support"
+	default n
+	depends on PRINTK
+
+config DYNAMIC_PRINTK_DEBUG
+	bool "Enable dynamic printk() call support"
+	default n
+	depends on PRINTK
+	select PRINTK_DEBUG
+	help
+	  
+	  Allows pr_debug() and dev_dbg() calls to be dynamically enabled based
+	  upon their source module. Traditionally, these calls are only
+	  enabled if one set #define DEBUG and recompiled the kernel. This
+	  option obviates time consuming re-compiles.
+
+	  The impact of this compile option is a larger kerenl text size ~1%.
+	  However, if CONFIG_IMMEDIATE is set, the run-time impact is 
+	  negligible. Without CONFIG_IMMEDIATE set, a global variable is
+	  referenced for each pr_debug() and dev_dbg() calls.
+
+	  Usage:
+
+	  The printing of pr_debug() and dev_dbg() is controlled by the
+	  debugfs file, dynamic_printk/modules. This file contains a list of
+	  the active modules. To add and remove modules:
+
+		echo "add <module_name>" > dynamic_printk/modules
+		echo "remove <module_name>" > dynamic_printk/modules
+
+	  For example:
+
+		 echo "add kobject" > dynamic_printk/modules
+		 /sbin/modprobe <module>

lib/dynamic_printk.c new file +15 -0

@@ -0,0 +1,327 @@
+/*
+ * lib/dynamic_printk.c
+ *
+ * make pr_debug()/dev_dbg() calls runtime configurable based upon their
+ * their source module.
+ *
+ * Copyright (C) 2008 Red Hat, Inc., Jason Baron <[email protected]>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+#include <linux/fs.h>

lib/dynamic_printk.c new file +25 -0

+static int nr_entries;
+
+int dynamic_printk_enabled[NR_CPUS];
+EXPORT_SYMBOL_GPL(dynamic_printk_enabled);
+
+struct debug_name {
+	struct hlist_node hlist;
+	char *name;
+	unsigned int num_uses;
+	int enable;
+	int flags;
+	int level;
+	int ratelimit;
+};
+
+static struct debug_name *find_debug_file(char *module_name)
+{
+	int found = 0;
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct debug_name *element;
+
+	head = &module_table[dynamic_name_hash(module_name)];
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(element, node, head, hlist) {

lib/dynamic_printk.c new file +13 -0

+	/* add error checking */
+	down(&debug_list_mutex);
+	add_debug_file(module_name);
+	elem = find_debug_file(module_name);
+	elem->num_uses++;
+	up(&debug_list_mutex);
+}
+EXPORT_SYMBOL_GPL(add_module);
+
+int remove_debug_file(char *module_name)
+{
+	struct debug_name *element;
+

lib/dynamic_printk.c new file +9 -0

+{	
+	struct debug_name *e;
+	struct hlist_node *node;		
+	int i, cpu, enable_mask;
+
+	for (i = 0; i < FILE_TABLE_SIZE; i++) {
+		if (module_table[i].first != NULL) {
+			hlist_for_each_entry(e, node, &module_table[i], hlist) {
+				e->enable = enable;

lib/dynamic_printk.c new file +19 -0

+		disable_all();
+		num_enabled = 0;
+		err = 0;
+	} else if (!strncmp("enable ", buffer, 7)) {
+		s = strstrip(buffer + 7);
+		if (elem = find_debug_file(s)) {
+			if (elem->enable == 0) {
+				hash = dynamic_name_hash(s);
+				for (i = 0; i < NR_CPUS; i++)
+					dynamic_printk_enabled[i] |= (1 << hash);
+				elem->enable = 1;
+				num_enabled++;
+			}
+			err = 0;
+		}	
+	} else if (!strncmp("disable ", buffer, 8)) {
+		s = strstrip(buffer + 8);
+		if (elem = find_debug_file(s)) {
+			if (elem->enable == 1) {

lib/dynamic_printk.c new file +48 -0

+	return err;
+}
+
+static void *pr_debug_seq_start(struct seq_file *f, loff_t *pos)
+{
+	return (*pos < FILE_TABLE_SIZE) ? pos : NULL;
+}
+
+static void *pr_debug_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	(*pos)++;
+	if (*pos >= FILE_TABLE_SIZE)
+		return NULL;
+	return pos;
+}
+
+static void pr_debug_seq_stop(struct seq_file *s, void *v)
+{
+	/* Nothing to do */
+}
+
+static int pr_debug_seq_show(struct seq_file *s, void *v)
+{
+	struct hlist_head *head;
+	struct hlist_node *node;
+	struct debug_name *element;
+	unsigned int i = *(loff_t *) v;
+
+	rcu_read_lock();
+	head = &module_table[i];
+	hlist_for_each_entry_rcu(element, node, head, hlist)
+		seq_printf(s, "%s %d %d\n", element->name, element->enable,
+				 element->num_uses);
+	rcu_read_unlock();
+	return 0;
+}
+
+static struct seq_operations pr_debug_seq_ops = {
+	.start = pr_debug_seq_start,
+	.next  = pr_debug_seq_next,
+	.stop  = pr_debug_seq_stop,
+	.show  = pr_debug_seq_show
+};
+
+static int pr_debug_open(struct inode *inode, struct file *filp)
+{
+	return seq_open(filp, &pr_debug_seq_ops);
+}

lib/dynamic_printk.c new file +6 -0

+{
+	struct dentry *dir, *file;
+	struct mod_debug *iter;
+
+	dir = debugfs_create_dir("dynamic_printk", NULL);
+	if (!dir)