Re: [PATCH 1/7] dynamic debug v2 - infrastructure

Jason Baron
2008-08-12T20:49:13Z

On Tue, Aug 12, 2008 at 01:09:08PM -0700, Greg KH wrote:
> So close, can I have a good changelog comment with the patch so people
> know what it is when they look in the logs?
>
> Care to resend it with that?
>

Base infrastructure to enable per-module debug messages.

I've introduced CONFIG_DYNAMIC_PRINTK_DEBUG, which when enabled centralizes
control of debugging statements on a per-module basis in one /proc file,
currently, <debugfs>/dynamic_printk/modules. When, CONFIG_DYNAMIC_PRINTK_DEBUG,
is not set, debugging statements can still be enabled as before, often by
defining 'DEBUG' for the proper compilation unit. Thus, this patch set has no
affect when CONFIG_DYNAMIC_PRINTK_DEBUG is not set.

The infrastructure currently ties into all pr_debug() and dev_dbg() calls. That
is, if CONFIG_DYNAMIC_PRINTK_DEBUG is set, all pr_debug() and dev_dbg() calls
can be dynamically enabled/disabled on a per-module basis.

Future plans include extending this functionality to subsystems, that define
their own debug levels and flags.

Usage:

Dynamic debugging is controlled by the debugfs file,
<debugfs>/dynamic_printk/modules. This file contains a list of the modules that
can be enabled. The format of the file is as follows:

<module_name> <enabled=0/1>
.
.
.

<module_name> : Name of the module in which the debug call resides
<enabled=0/1> : whether the messages are enabled or not

For example:

snd_hda_intel enabled=0
fixup enabled=1
driver enabled=0

Enable a module:

$echo "set enabled=1 <module_name>" > dynamic_printk/modules

Disable a module:

$echo "set enabled=0 <module_name>" > dynamic_printk/modules

Enable all modules:

$echo "set enabled=1 all" > dynamic_printk/modules

Disable all modules:

$echo "set enabled=0 all" > dynamic_printk/modules

Finally, passing "dynamic_printk" at the command line enables
debugging for all modules. This mode can be turned off via the above
disable command.

Signed-off-by: Jason Baron <jbaron@redhat.com>

---

Documentation/kernel-parameters.txt | 5
include/asm-generic/vmlinux.lds.h | 10 +
include/linux/device.h | 6 -
include/linux/dynamic_printk.h | 96 ++++++++
include/linux/kernel.h | 7 +
include/linux/module.h | 4
kernel/module.c | 22 ++
lib/Kconfig.debug | 55 +++++
lib/Makefile | 2
lib/dynamic_printk.c | 413 +++++++++++++++++++++++++++++++++++
net/netfilter/nf_conntrack_pptp.c | 2
scripts/Makefile.lib | 11 +
scripts/basic/Makefile | 2
scripts/basic/hash.c | 64 +++++
14 files changed, 693 insertions(+), 6 deletions(-)
create mode 100644 include/linux/dynamic_printk.h
create mode 100644 lib/dynamic_printk.c
create mode 100644 scripts/basic/hash.c

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bf6303e..7c60e89 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1580,6 +1580,11 @@ and is between 256 and 4096 characters. It is defined in the file
autoconfiguration.
Ranges are in pairs (memory base and size).

+ dynamic_printk
+ Enables pr_debug()/dev_dbg() calls if
+ CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
+ be switched on/off via <debugfs>/dynamic_printk/modules
+
print-fatal-signals=
[KNL] debug: print fatal signals
print-fatal-signals=1: print segfault info to
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f054778..00804e0 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -249,7 +249,15 @@
CPU_DISCARD(init.data) \
CPU_DISCARD(init.rodata) \
MEM_DISCARD(init.data) \
- MEM_DISCARD(init.rodata)
+ MEM_DISCARD(init.rodata) \
+ /* implement dynamic printk debug */ \
+ VMLINUX_SYMBOL(__start___verbose_strings) = .; \
+ *(__verbose_strings) \
+ VMLINUX_SYMBOL(__stop___verbose_strings) = .; \
+ . = ALIGN(8); \
+ VMLINUX_SYMBOL(__start___verbose) = .; \
+ *(__verbose) \
+ VMLINUX_SYMBOL(__stop___verbose) = .;

#define INIT_TEXT \
*(.init.text) \
diff --git a/include/linux/device.h b/include/linux/device.h
index 1a06026..fb03dbc 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -592,7 +592,11 @@ extern const char *dev_driver_string(struct device *dev);
#define dev_info(dev, format, arg...) \
dev_printk(KERN_INFO , dev , format , ## arg)

-#ifdef DEBUG
+#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
+#define dev_dbg(dev, format, ...) do { \
+ dynamic_dev_dbg(dev, format, ##__VA_ARGS__); \
+ } while (0)
+#elif defined(DEBUG)
#define dev_dbg(dev, format, arg...) \
dev_printk(KERN_DEBUG , dev , format , ## arg)
#else
diff --git a/include/linux/dynamic_printk.h b/include/linux/dynamic_printk.h
new file mode 100644
index 0000000..210bf61
--- /dev/null
+++ b/include/linux/dynamic_printk.h
@@ -0,0 +1,96 @@
+#ifndef _DYNAMIC_PRINTK_H
+#define _DYNAMIC_PRINTK_H
+
+#include <linux/string.h>
+#include <linux/hash.h>
+
+#define DYNAMIC_DEBUG_HASH_BITS 6
+#define DEBUG_HASH_TABLE_SIZE (1 << DYNAMIC_DEBUG_HASH_BITS)
+
+#define TYPE_BOOLEAN 1
+
+#define DYNAMIC_ENABLED_ALL 0
+#define DYNAMIC_ENABLED_NONE 1
+#define DYNAMIC_ENABLED_SOME 2
+
+extern int dynamic_enabled;
+
+/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
+ * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
+ * use independent hash functions, to reduce the chance of false positives.
+ */
+extern long long dynamic_printk_enabled;
+extern long long dynamic_printk_enabled2;
+
+struct mod_debug {
+ char *modname;
+ char *logical_modname;
+ char *flag_names;
+ int type;
+ int hash;
+ int hash2;
+} __attribute__((aligned(8)));
+
+int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
+ char *flags, int hash, int hash2);
+
+#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
+extern int unregister_dynamic_debug_module(char *mod_name);
+extern int __dynamic_dbg_enabled_helper(char *modname, int type,
+ int value, int hash);
+
+#define __dynamic_dbg_enabled(module, type, value, level, hash) ({ \
+ int ret = 0; \
+ if (unlikely((dynamic_printk_enabled & (1LL << DEBUG_HASH)) && \
+ (dynamic_printk_enabled2 & (1LL << DEBUG_HASH2)))) \
+ ret = __dynamic_dbg_enabled_helper(module, type, \
+ value, hash);\
+ ret; })
+
+#define dynamic_pr_debug(fmt, ...) do { \
+ static char mod_name[] \
+ __attribute__((section("__verbose_strings"))) \
+ = KBUILD_MODNAME; \
+ static struct mod_debug descriptor \
+ __used \
+ __attribute__((section("__verbose"), aligned(8))) = \
+ { mod_name, mod_name, NULL, TYPE_BOOLEAN, DEBUG_HASH, DEBUG_HASH2 };\
+ if (__dynamic_dbg_enabled(KBUILD_MODNAME, TYPE_BOOLEAN, \
+ 0, 0, DEBUG_HASH)) \
+ printk(KERN_DEBUG KBUILD_MODNAME ":" fmt, \
+ ##__VA_ARGS__); \
+ } while (0)
+
+#define dynamic_dev_dbg(dev, format, ...) do { \
+ static char mod_name[] \
+ __attribute__((section("__verbose_strings"))) \
+ = KBUILD_MODNAME; \
+ static struct mod_debug descriptor \
+ __used \
+ __attribute__((section("__verbose"), aligned(8))) = \
+ { mod_name, mod_name, NULL, TYPE_BOOLEAN, DEBUG_HASH, DEBUG_HASH2 };\
+ if (__dynamic_dbg_enabled(KBUILD_MODNAME, TYPE_BOOLEAN, \
+ 0, 0, DEBUG_HASH)) \
+ dev_printk(KERN_DEBUG, dev, \
+ KBUILD_MODNAME ": " format, \
+ ##__VA_ARGS__); \
+ } while (0)
+
+#else
+
+static inline int unregister_dynamic_debug_module(const char *mod_name)
+{
+ return 0;
+}
+static inline int __dynamic_dbg_enabled_helper(char *modname, int type,
+ int value, int hash)
+{
+ return 0;
+}
+
+#define __dynamic_dbg_enabled(module, type, value, level, hash) ({ 0; })
+#define dynamic_pr_debug(fmt, ...) do { } while (0)
+#define dynamic_dev_dbg(dev, format, ...) do { } while (0)
+#endif
+
+#endif
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index cd6d02c..25d09b8 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -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>

@@ -288,8 +289,12 @@ extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
#define pr_info(fmt, arg...) \
printk(KERN_INFO fmt, ##arg)

-#ifdef DEBUG
/* If you are writing a driver, please use dev_dbg instead */
+#if defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
+#define pr_debug(fmt, ...) do { \
+ dynamic_pr_debug(fmt, ##__VA_ARGS__); \
+ } while (0)
+#elif defined(DEBUG)
#define pr_debug(fmt, arg...) \
printk(KERN_DEBUG fmt, ##arg)
#else
diff --git a/include/linux/module.h b/include/linux/module.h
index 819c4e8..74a2e32 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -359,6 +359,10 @@ struct module
struct marker *markers;
unsigned int num_markers;
#endif
+#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
+ struct mod_debug *start_verbose;
+ unsigned int num_verbose;
+#endif
};
#ifndef MODULE_ARCH_INIT
#define MODULE_ARCH_INIT {}
diff --git a/kernel/module.c b/kernel/module.c
index 8d6cccc..ad7a105 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -744,6 +744,7 @@ sys_delete_module(const char __user *name_user, unsigned int flags)
}
/* Store the name of the last unloaded module for diagnostic purposes */
strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
+ unregister_dynamic_debug_module(mod->name);
free_module(mod);

out:
@@ -1717,6 +1718,9 @@ static struct module *load_module(void __user *umod,
unsigned int unusedgplcrcindex;
unsigned int markersindex;
unsigned int markersstringsindex;
+ unsigned int verboseindex;
+ struct mod_debug *iter;
+ unsigned long value;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -1993,6 +1997,7 @@ 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");

/* Now do relocations. */
for (i = 1; i < hdr->e_shnum; i++) {
@@ -2020,6 +2025,11 @@ static struct module *load_module(void __user *umod,
mod->num_markers =
sechdrs[markersindex].sh_size / sizeof(*mod->markers);
#endif
+#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
+ mod->start_verbose = (void *)sechdrs[verboseindex].sh_addr;
+ mod->num_verbose = sechdrs[verboseindex].sh_size /
+ sizeof(*mod->start_verbose);
+#endif

/* Find duplicate symbols */
err = verify_export_symbols(mod);
@@ -2043,6 +2053,18 @@ static struct module *load_module(void __user *umod,
marker_update_probe_range(mod->markers,
mod->markers + mod->num_markers);
#endif
+#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
+ for (value = (unsigned long)mod->start_verbose;
+ value < (unsigned long)mod->start_verbose +
+ (unsigned long)(mod->num_verbose * sizeof(struct mod_debug));
+ value += sizeof(struct mod_debug)) {
+ iter = (struct mod_debug *)value;
+ register_dynamic_debug_module(iter->modname,
+ iter->type,
+ iter->logical_modname,
+ iter->flag_names, iter->hash, iter->hash2);
+ }
+#endif
err = module_finalize(hdr, sechdrs, mod);
if (err < 0)
goto cleanup;
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 623ef24..01b2a23 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -632,6 +632,61 @@ config FIREWIRE_OHCI_REMOTE_DMA

If unsure, say N.

+config DYNAMIC_PRINTK_DEBUG
+ bool "Enable dynamic printk() call support"
+ default n
+ depends on PRINTK
+ select PRINTK_DEBUG
+ help
+
+ Compiles debug level messages into the kernel, which would not
+ otherwise be available at runtime. These messages can then be
+ enabled/disabled on a per module basis. This mechanism implicitly
+ enables all pr_debug() and dev_dbg() calls. The impact of this
+ compile option is a larger kernel text size of about 2%.
+
+ Usage:
+
+ Dynamic debugging is controlled by the debugfs file,
+ dynamic_printk/modules. This file contains a list of the modules that
+ can be enabled. The format of the file is the module name, followed
+ by a set of flags that can be enabled. The first flag is always the
+ 'enabled' flag. For example:
+
+ <module_name> <enabled=0/1>
+ .
+ .
+ .
+
+ <module_name> : Name of the module in which the debug call resides
+ <enabled=0/1> : whether the messages are enabled or not
+
+ From a live system:
+
+ snd_hda_intel enabled=0
+ fixup enabled=0
+ driver enabled=0
+
+ Enable a module:
+
+ $echo "set enabled=1 <module_name>" > dynamic_printk/modules
+
+ Disable a module:
+
+ $echo "set enabled=0 <module_name>" > dynamic_printk/modules
+
+ Enable all modules:
+
+ $echo "set enabled=1 all" > dynamic_printk/modules
+
+ Disable all modules:
+
+ $echo "set enabled=0 all" > dynamic_printk/modules
+
+ Finally, passing "dynamic_printk" at the command line enables
+ debugging for all modules. This mode can be turned off via the above
+ disable command.
+
source "samples/Kconfig"

source "lib/Kconfig.kgdb"
diff --git a/lib/Makefile b/lib/Makefile
index bf8000f..78ab656 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -70,6 +70,8 @@ lib-$(CONFIG_GENERIC_BUG) += bug.o

obj-$(CONFIG_HAVE_LMB) += lmb.o

+obj-$(CONFIG_DYNAMIC_PRINTK_DEBUG) += dynamic_printk.o
+
hostprogs-y := gen_crc32table
clean-files := crc32table.h

diff --git a/lib/dynamic_printk.c b/lib/dynamic_printk.c
new file mode 100644
index 0000000..ea679ec
--- /dev/null
+++ b/lib/dynamic_printk.c
@@ -0,0 +1,413 @@
+/*
+ * 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 <jbaron@redhat.com>
+ */
+
+#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>
+
+extern struct mod_debug __start___verbose[];
+extern struct mod_debug __stop___verbose[];
+
+struct debug_name {
+ struct hlist_node hlist;
+ struct hlist_node hlist2;
+ int hash1;
+ int hash2;
+ char *name;
+ int enable;
+ int type;
+};
+
+static int nr_entries;
+static int num_enabled;
+int dynamic_enabled = DYNAMIC_ENABLED_NONE;
+static struct hlist_head module_table[DEBUG_HASH_TABLE_SIZE] =
+ { [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
+static struct hlist_head module_table2[DEBUG_HASH_TABLE_SIZE] =
+ { [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
+static DECLARE_MUTEX(debug_list_mutex);
+
+/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
+ * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
+ * use independent hash functions, to reduce the chance of false positives.
+ */
+long long dynamic_printk_enabled;
+EXPORT_SYMBOL_GPL(dynamic_printk_enabled);
+long long dynamic_printk_enabled2;
+EXPORT_SYMBOL_GPL(dynamic_printk_enabled2);
+
+/* returns the debug module pointer. */
+static struct debug_name *find_debug_module(char *module_name)
+{
+ int i;
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct debug_name *element;
+
+ element = NULL;
+ for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
+ head = &module_table[i];
+ hlist_for_each_entry_rcu(element, node, head, hlist)
+ if (!strcmp(element->name, module_name))
+ return element;
+ }
+ return NULL;
+}
+
+/* returns the debug module pointer. */
+static struct debug_name *find_debug_module_hash(char *module_name, int hash)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct debug_name *element;
+
+ element = NULL;
+ head = &module_table[hash];
+ hlist_for_each_entry_rcu(element, node, head, hlist)
+ if (!strcmp(element->name, module_name))
+ return element;
+ return NULL;
+}
+
+/* caller must hold mutex*/
+static int __add_debug_module(char *mod_name, int hash, int hash2)
+{
+ struct debug_name *new;
+ char *module_name;
+ int ret = 0;
+
+ if (find_debug_module(mod_name)) {
+ ret = -EINVAL;
+ goto out;
+ }
+ module_name = kmalloc(strlen(mod_name) + 1, GFP_KERNEL);
+ if (!module_name) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ module_name = strcpy(module_name, mod_name);
+ module_name[strlen(mod_name)] = '\0';
+ new = kzalloc(sizeof(struct debug_name), GFP_KERNEL);
+ if (!new) {
+ kfree(module_name);
+ ret = -ENOMEM;
+ goto out;
+ }
+ INIT_HLIST_NODE(&new->hlist);
+ INIT_HLIST_NODE(&new->hlist2);
+ new->name = module_name;
+ new->hash1 = hash;
+ new->hash2 = hash2;
+ hlist_add_head_rcu(&new->hlist, &module_table[hash]);
+ hlist_add_head_rcu(&new->hlist2, &module_table2[hash2]);
+ nr_entries++;
+out:
+ return ret;
+}
+
+int unregister_dynamic_debug_module(char *mod_name)
+{
+ struct debug_name *element;
+ int ret = 0;
+
+ down(&debug_list_mutex);
+ element = find_debug_module(mod_name);
+ if (!element) {
+ ret = -EINVAL;
+ goto out;
+ }
+ hlist_del_rcu(&element->hlist);
+ hlist_del_rcu(&element->hlist2);
+ synchronize_rcu();
+ if (element->name)
+ kfree(element->name);
+ if (element->enable)
+ num_enabled--;
+ kfree(element);
+ nr_entries--;
+out:
+ up(&debug_list_mutex);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(unregister_dynamic_debug_module);
+
+int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
+ char *flags, int hash, int hash2)
+{
+ struct debug_name *elem;
+ int ret = 0;
+
+ down(&debug_list_mutex);
+ elem = find_debug_module(mod_name);
+ if (!elem) {
+ if (__add_debug_module(mod_name, hash, hash2))
+ goto out;
+ elem = find_debug_module(mod_name);
+ if (dynamic_enabled == DYNAMIC_ENABLED_ALL &&
+ !strcmp(mod_name, share_name)) {
+ elem->enable = true;
+ num_enabled++;
+ }
+ }
+ elem->type |= type;
+out:
+ up(&debug_list_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(register_dynamic_debug_module);
+
+int __dynamic_dbg_enabled_helper(char *mod_name, int type, int value, int hash)
+{
+ struct debug_name *elem;
+ int ret = 0;
+
+ if (dynamic_enabled == DYNAMIC_ENABLED_ALL)
+ return 1;
+ rcu_read_lock();
+ elem = find_debug_module_hash(mod_name, hash);
+ if (elem && elem->enable)
+ ret = 1;
+ rcu_read_unlock();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(__dynamic_dbg_enabled_helper);
+
+static void set_all(bool enable)
+{
+ struct debug_name *e;
+ struct hlist_node *node;
+ int i;
+ long long enable_mask;
+
+ for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
+ if (module_table[i].first != NULL) {
+ hlist_for_each_entry(e, node, &module_table[i], hlist) {
+ e->enable = enable;
+ }
+ }
+ }
+ if (enable)
+ enable_mask = ULLONG_MAX;
+ else
+ enable_mask = 0;
+ dynamic_printk_enabled = enable_mask;
+ dynamic_printk_enabled2 = enable_mask;
+}
+
+static int disabled_hash(int i, bool first_table)
+{
+ struct debug_name *e;
+ struct hlist_node *node;
+
+ if (first_table) {
+ hlist_for_each_entry(e, node, &module_table[i], hlist) {
+ if (e->enable)
+ return 0;
+ }
+ } else {
+ hlist_for_each_entry(e, node, &module_table2[i], hlist2) {
+ if (e->enable)
+ return 0;
+ }
+ }
+ return 1;
+}
+
+static ssize_t pr_debug_write(struct file *file, const char __user *buf,
+ size_t length, loff_t *ppos)
+{
+ char *buffer, *s, *value_str, *setting_str;
+ int err, value;
+ struct debug_name *elem = NULL;
+ int all = 0;
+
+ if (length > PAGE_SIZE || length < 0)
+ return -EINVAL;
+
+ buffer = (char *)__get_free_page(GFP_KERNEL);
+ if (!buffer)
+ return -ENOMEM;
+
+ err = -EFAULT;
+ if (copy_from_user(buffer, buf, length))
+ goto out;
+
+ err = -EINVAL;
+ if (length < PAGE_SIZE)
+ buffer[length] = '\0';
+ else if (buffer[PAGE_SIZE-1])
+ goto out;
+
+ err = -EINVAL;
+ down(&debug_list_mutex);
+
+ if (strncmp("set", buffer, 3))
+ goto out_up;
+ s = buffer + 3;
+ setting_str = strsep(&s, "=");
+ if (s == NULL)
+ goto out_up;
+ setting_str = strstrip(setting_str);
+ value_str = strsep(&s, " ");
+ if (s == NULL)
+ goto out_up;
+ s = strstrip(s);
+ if (!strncmp(s, "all", 3))
+ all = 1;
+ else
+ elem = find_debug_module(s);
+ if (!strncmp(setting_str, "enable", 6)) {
+ value = !!simple_strtol(value_str, NULL, 10);
+ if (all) {
+ if (value) {
+ set_all(true);
+ num_enabled = nr_entries;
+ dynamic_enabled = DYNAMIC_ENABLED_ALL;
+ } else {
+ set_all(false);
+ num_enabled = 0;
+ dynamic_enabled = DYNAMIC_ENABLED_NONE;
+ }
+ err = 0;
+ } else {
+ if (elem) {
+ if (value && (elem->enable == 0)) {
+ dynamic_printk_enabled |=
+ (1LL << elem->hash1);
+ dynamic_printk_enabled2 |=
+ (1LL << elem->hash2);
+ elem->enable = 1;
+ num_enabled++;
+ dynamic_enabled = DYNAMIC_ENABLED_SOME;
+ err = 0;
+ } else if (!value && (elem->enable == 1)) {
+ elem->enable = 0;
+ num_enabled--;
+ if (disabled_hash(elem->hash1, true))
+ dynamic_printk_enabled &=
+ ~(1LL << elem->hash1);
+ if (disabled_hash(elem->hash2, false))
+ dynamic_printk_enabled2 &=
+ ~(1LL << elem->hash2);
+ if (num_enabled)
+ dynamic_enabled =
+ DYNAMIC_ENABLED_SOME;
+ else
+ dynamic_enabled =
+ DYNAMIC_ENABLED_NONE;
+ err = 0;
+ }
+ }
+ }
+ }
+ if (!err)
+ err = length;
+out_up:
+ up(&debug_list_mutex);
+out:
+ free_page((unsigned long)buffer);
+ return err;
+}
+
+static void *pr_debug_seq_start(struct seq_file *f, loff_t *pos)
+{
+ return (*pos < DEBUG_HASH_TABLE_SIZE) ? pos : NULL;
+}
+
+static void *pr_debug_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ (*pos)++;
+ if (*pos >= DEBUG_HASH_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 *elem;
+ unsigned int i = *(loff_t *) v;
+
+ rcu_read_lock();
+ head = &module_table[i];
+ hlist_for_each_entry_rcu(elem, node, head, hlist) {
+ seq_printf(s, "%s enabled=%d", elem->name, elem->enable);
+ seq_printf(s, "\n");
+ }
+ 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);
+}
+
+static const struct file_operations pr_debug_operations = {
+ .open = pr_debug_open,
+ .read = seq_read,
+ .write = pr_debug_write,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+int __init dynamic_printk_init(void)
+{
+ struct dentry *dir, *file;
+ struct mod_debug *iter;
+ unsigned long value;
+
+ dir = debugfs_create_dir("dynamic_printk", NULL);
+ if (!dir)
+ return -ENOMEM;
+ file = debugfs_create_file("modules", 0644, dir, NULL,
+ &pr_debug_operations);
+ if (!file) {
+ debugfs_remove(dir);
+ return -ENOMEM;
+ }
+ for (value = (unsigned long)__start___verbose;
+ value < (unsigned long)__stop___verbose;
+ value += sizeof(struct mod_debug)) {
+ iter = (struct mod_debug *)value;
+ register_dynamic_debug_module(iter->modname,
+ iter->type,
+ iter->logical_modname,
+ iter->flag_names, iter->hash, iter->hash2);
+ }
+ return 0;
+}
+module_init(dynamic_printk_init);
+/* may want to move this earlier so we can get traces as early as possible */
+
+static int __init dynamic_printk_setup(char *str)
+{
+ if (str)
+ return -ENOENT;
+ set_all(true);
+ return 0;
+}
+/* Use early_param(), so we can get debug output as early as possible */
+early_param("dynamic_printk", dynamic_printk_setup);
diff --git a/net/netfilter/nf_conntrack_pptp.c b/net/netfilter/nf_conntrack_pptp.c
index 97e54b0..7fea304 100644
--- a/net/netfilter/nf_conntrack_pptp.c
+++ b/net/netfilter/nf_conntrack_pptp.c
@@ -65,7 +65,7 @@ void
struct nf_conntrack_expect *exp) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_pptp_hook_expectfn);

-#ifdef DEBUG
+#if defined(DEBUG) || defined(CONFIG_DYNAMIC_PRINTK_DEBUG)
/* PptpControlMessageType names */
const char *const pptp_msg_name[] = {
"UNKNOWN_MESSAGE",
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 8e44023..1e393cf 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -96,6 +96,14 @@ basename_flags = -D"KBUILD_BASENAME=KBUILD_STR($(call name-fix,$(basetarget)))"
modname_flags = $(if $(filter 1,$(words $(modname))),\
-D"KBUILD_MODNAME=KBUILD_STR($(call name-fix,$(modname)))")

+#hash values
+ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
+debug_flags = -D"DEBUG_HASH=$(shell ./scripts/basic/hash djb2 $(@D)$(modname))"\
+ -D"DEBUG_HASH2=$(shell ./scripts/basic/hash r5 $(@D)$(modname))"
+else
+debug_flags =
+endif
+
_c_flags = $(KBUILD_CFLAGS) $(ccflags-y) $(CFLAGS_$(basetarget).o)
_a_flags = $(KBUILD_AFLAGS) $(asflags-y) $(AFLAGS_$(basetarget).o)
_cpp_flags = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(@F))
@@ -120,7 +128,8 @@ endif

c_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) \
$(__c_flags) $(modkern_cflags) \
- -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags)
+ -D"KBUILD_STR(s)=\#s" $(basename_flags) $(modname_flags) \
+ $(debug_flags)

a_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) \
$(__a_flags) $(modkern_aflags)
diff --git a/scripts/basic/Makefile b/scripts/basic/Makefile
index 4c324a1..0955995 100644
--- a/scripts/basic/Makefile
+++ b/scripts/basic/Makefile
@@ -9,7 +9,7 @@
# fixdep: Used to generate dependency information during build process
# docproc: Used in Documentation/DocBook

-hostprogs-y := fixdep docproc
+hostprogs-y := fixdep docproc hash
always := $(hostprogs-y)

# fixdep is needed to compile other host programs
diff --git a/scripts/basic/hash.c b/scripts/basic/hash.c
new file mode 100644
index 0000000..3299ad7
--- /dev/null
+++ b/scripts/basic/hash.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DYNAMIC_DEBUG_HASH_BITS 6
+
+static const char *program;
+
+static void usage(void)
+{
+ printf("Usage: %s <djb2|r5> <modname>\n", program);
+ exit(1);
+}
+
+/* djb2 hashing algorithm by Dan Bernstein. From:
+ * http://www.cse.yorku.ca/~oz/hash.html
+ */
+
+unsigned int djb2_hash(char *str)
+{
+ unsigned long hash = 5381;
+ int c;
+
+ c = *str;
+ while (c) {
+ hash = ((hash << 5) + hash) + c;
+ c = *++str;
+ }
+ return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
+}
+
+unsigned int r5_hash(char *str)
+{
+ unsigned long hash = 0;
+ int c;
+
+ c = *str;
+ while (c) {
+ hash = (hash + (c << 4) + (c >> 4)) * 11;
+ c = *++str;
+ }
+ return (unsigned int)(hash & ((1 << DYNAMIC_DEBUG_HASH_BITS) - 1));
+}
+
+int main(int argc, char *argv[])
+{
+ program = argv[0];
+
+ if (argc != 3)
+ usage();
+ if (!strcmp(argv[1], "djb2"))
+ printf("%d\n", djb2_hash(argv[2]));
+ else if (!strcmp(argv[1], "r5"))
+ printf("%d\n", r5_hash(argv[2]));
+ else
+ usage();
+ exit(0);
+}
+