From 346e15beb5343c2eb8216d820f2ed8f150822b08 Mon Sep 17 00:00:00 2001 From: Jason Baron Date: Tue, 12 Aug 2008 16:46:19 -0400 Subject: driver core: basic infrastructure for per-module dynamic debug messages 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, /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, /dynamic_printk/modules. This file contains a list of the modules that can be enabled. The format of the file is as follows: . . . : Name of the module in which the debug call resides : 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 " > dynamic_printk/modules Disable a module: $echo "set enabled=0 " > 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. [gkh: minor cleanups and tweaks to make the build work quietly] Signed-off-by: Jason Baron Signed-off-by: Greg Kroah-Hartman --- lib/Kconfig.debug | 55 +++++++ lib/Makefile | 2 + lib/dynamic_printk.c | 418 +++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 475 insertions(+) create mode 100644 lib/dynamic_printk.c (limited to 'lib') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index aa81d284844..31d784dd80d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -807,6 +807,61 @@ menuconfig BUILD_DOCSRC Say N if you are unsure. +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: + + + . + . + . + + : Name of the module in which the debug call resides + : 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 " > dynamic_printk/modules + + Disable a module: + + $echo "set enabled=0 " > dynamic_printk/modules + + Enable all modules: + + $echo "set enabled=1 all" > dynamic_printk/modules + + Disable all modules: + + $echo "set enabled=0 all" > dynamic_printk/modules + + Finally, passing "dynamic_printk" at the command line enables + debugging for all modules. This mode can be turned off via the above + disable command. + source "samples/Kconfig" source "lib/Kconfig.kgdb" diff --git a/lib/Makefile b/lib/Makefile index 44001af76a7..16feaab057b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -81,6 +81,8 @@ obj-$(CONFIG_HAVE_LMB) += lmb.o obj-$(CONFIG_HAVE_ARCH_TRACEHOOK) += syscall.o +obj-$(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 00000000000..d640f87bdc9 --- /dev/null +++ b/lib/dynamic_printk.c @@ -0,0 +1,418 @@ +/* + * 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 + */ + +#include +#include +#include +#include +#include +#include + +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(); + 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; + printk(KERN_DEBUG + "debugging enabled for module %s", + elem->name); + } 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; + printk(KERN_DEBUG + "debugging disabled for module " + "%s", elem->name); + } + } + } + } + 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, +}; + +static 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); -- cgit v1.2.3 From 030c1d2bfcc2187650fb975456ca0b61a5bb77f4 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 8 May 2008 14:41:00 -0700 Subject: kobject: Fix kobject_rename and !CONFIG_SYSFS When looking at kobject_rename I found two bugs with that exist when sysfs support is disabled in the kernel. kobject_rename does not change the name on the kobject when sysfs support is not compiled in. kobject_rename without locking attempts to check the validity of a rename operation, which the kobject layer simply does not have the infrastructure to do. This patch documents the previously unstated requirement of kobject_rename that is the responsibility of the caller to provide mutual exclusion and to be certain that the new_name for the kobject is valid. This patch modifies sysfs_rename_dir in !CONFIG_SYSFS case to call kobject_set_name to actually change the kobject_name. This patch removes the bogus and misleading check in kobject_rename that attempts to see if a rename is valid. The check is bogus because we do not have the proper locking. The check is misleading because it looks like we can and do perform checking at the kobject level that we don't. Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- lib/kobject.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) (limited to 'lib') diff --git a/lib/kobject.c b/lib/kobject.c index fbf0ae28237..ae6bb900bfb 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -387,6 +387,11 @@ EXPORT_SYMBOL_GPL(kobject_init_and_add); * kobject_rename - change the name of an object * @kobj: object in question. * @new_name: object's new name + * + * It is the responsibility of the caller to provide mutual + * exclusion between two different calls of kobject_rename + * on the same kobject and to ensure that new_name is valid and + * won't conflict with other kobjects. */ int kobject_rename(struct kobject *kobj, const char *new_name) { @@ -401,19 +406,6 @@ int kobject_rename(struct kobject *kobj, const char *new_name) if (!kobj->parent) return -EINVAL; - /* see if this name is already in use */ - if (kobj->kset) { - struct kobject *temp_kobj; - temp_kobj = kset_find_obj(kobj->kset, new_name); - if (temp_kobj) { - printk(KERN_WARNING "kobject '%s' cannot be renamed " - "to '%s' as '%s' is already in existence.\n", - kobject_name(kobj), new_name, new_name); - kobject_put(temp_kobj); - return -EINVAL; - } - } - devpath = kobject_get_path(kobj, GFP_KERNEL); if (!devpath) { error = -ENOMEM; -- cgit v1.2.3 From 0b4a4fea253e1296222603ccc55430ed7cd9413a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Thu, 3 Jul 2008 18:05:28 -0700 Subject: kobject: Cleanup kobject_rename and !CONFIG_SYSFS It finally dawned on me what the clean fix to sysfs_rename_dir calling kobject_set_name is. Move the work into kobject_rename where it belongs. The callers serialize us anyway so this is safe. Signed-off-by: Eric W. Biederman Acked-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- lib/kobject.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) (limited to 'lib') diff --git a/lib/kobject.c b/lib/kobject.c index ae6bb900bfb..0487d1f6480 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -397,6 +397,7 @@ int kobject_rename(struct kobject *kobj, const char *new_name) { int error = 0; const char *devpath = NULL; + const char *dup_name = NULL, *name; char *devpath_string = NULL; char *envp[2]; @@ -420,15 +421,27 @@ int kobject_rename(struct kobject *kobj, const char *new_name) envp[0] = devpath_string; envp[1] = NULL; + name = dup_name = kstrdup(new_name, GFP_KERNEL); + if (!name) { + error = -ENOMEM; + goto out; + } + error = sysfs_rename_dir(kobj, new_name); + if (error) + goto out; + + /* Install the new kobject name */ + dup_name = kobj->name; + kobj->name = name; /* This function is mostly/only used for network interface. * Some hotplug package track interfaces by their name and * therefore want to know when the name is changed by the user. */ - if (!error) - kobject_uevent_env(kobj, KOBJ_MOVE, envp); + kobject_uevent_env(kobj, KOBJ_MOVE, envp); out: + kfree(dup_name); kfree(devpath_string); kfree(devpath); kobject_put(kobj); -- cgit v1.2.3