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![Wu Fengguang](/assets/img/avatar_default.png)
Cleanup pr_debug_write() to reduce one level of indentation. Cc: Marcel Holtmann <marcel@holtmann.org> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
414 lines
9.5 KiB
C
414 lines
9.5 KiB
C
/*
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* lib/dynamic_printk.c
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*
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* make pr_debug()/dev_dbg() calls runtime configurable based upon their
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* their source module.
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*
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* Copyright (C) 2008 Red Hat, Inc., Jason Baron <jbaron@redhat.com>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/seq_file.h>
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#include <linux/debugfs.h>
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#include <linux/fs.h>
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extern struct mod_debug __start___verbose[];
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extern struct mod_debug __stop___verbose[];
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struct debug_name {
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struct hlist_node hlist;
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struct hlist_node hlist2;
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int hash1;
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int hash2;
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char *name;
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int enable;
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int type;
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};
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static int nr_entries;
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static int num_enabled;
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int dynamic_enabled = DYNAMIC_ENABLED_NONE;
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static struct hlist_head module_table[DEBUG_HASH_TABLE_SIZE] =
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{ [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
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static struct hlist_head module_table2[DEBUG_HASH_TABLE_SIZE] =
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{ [0 ... DEBUG_HASH_TABLE_SIZE-1] = HLIST_HEAD_INIT };
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static DECLARE_MUTEX(debug_list_mutex);
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/* dynamic_printk_enabled, and dynamic_printk_enabled2 are bitmasks in which
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* bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
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* use independent hash functions, to reduce the chance of false positives.
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*/
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long long dynamic_printk_enabled;
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EXPORT_SYMBOL_GPL(dynamic_printk_enabled);
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long long dynamic_printk_enabled2;
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EXPORT_SYMBOL_GPL(dynamic_printk_enabled2);
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/* returns the debug module pointer. */
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static struct debug_name *find_debug_module(char *module_name)
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{
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int i;
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struct hlist_head *head;
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struct hlist_node *node;
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struct debug_name *element;
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element = NULL;
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for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
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head = &module_table[i];
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hlist_for_each_entry_rcu(element, node, head, hlist)
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if (!strcmp(element->name, module_name))
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return element;
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}
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return NULL;
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}
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/* returns the debug module pointer. */
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static struct debug_name *find_debug_module_hash(char *module_name, int hash)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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struct debug_name *element;
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element = NULL;
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head = &module_table[hash];
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hlist_for_each_entry_rcu(element, node, head, hlist)
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if (!strcmp(element->name, module_name))
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return element;
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return NULL;
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}
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/* caller must hold mutex*/
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static int __add_debug_module(char *mod_name, int hash, int hash2)
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{
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struct debug_name *new;
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char *module_name;
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int ret = 0;
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if (find_debug_module(mod_name)) {
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ret = -EINVAL;
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goto out;
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}
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module_name = kmalloc(strlen(mod_name) + 1, GFP_KERNEL);
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if (!module_name) {
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ret = -ENOMEM;
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goto out;
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}
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module_name = strcpy(module_name, mod_name);
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module_name[strlen(mod_name)] = '\0';
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new = kzalloc(sizeof(struct debug_name), GFP_KERNEL);
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if (!new) {
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kfree(module_name);
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ret = -ENOMEM;
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goto out;
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}
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INIT_HLIST_NODE(&new->hlist);
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INIT_HLIST_NODE(&new->hlist2);
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new->name = module_name;
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new->hash1 = hash;
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new->hash2 = hash2;
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hlist_add_head_rcu(&new->hlist, &module_table[hash]);
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hlist_add_head_rcu(&new->hlist2, &module_table2[hash2]);
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nr_entries++;
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out:
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return ret;
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}
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int unregister_dynamic_debug_module(char *mod_name)
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{
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struct debug_name *element;
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int ret = 0;
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down(&debug_list_mutex);
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element = find_debug_module(mod_name);
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if (!element) {
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ret = -EINVAL;
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goto out;
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}
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hlist_del_rcu(&element->hlist);
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hlist_del_rcu(&element->hlist2);
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synchronize_rcu();
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kfree(element->name);
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if (element->enable)
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num_enabled--;
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kfree(element);
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nr_entries--;
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out:
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up(&debug_list_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(unregister_dynamic_debug_module);
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int register_dynamic_debug_module(char *mod_name, int type, char *share_name,
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char *flags, int hash, int hash2)
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{
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struct debug_name *elem;
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int ret = 0;
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down(&debug_list_mutex);
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elem = find_debug_module(mod_name);
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if (!elem) {
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if (__add_debug_module(mod_name, hash, hash2))
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goto out;
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elem = find_debug_module(mod_name);
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if (dynamic_enabled == DYNAMIC_ENABLED_ALL &&
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!strcmp(mod_name, share_name)) {
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elem->enable = true;
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num_enabled++;
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}
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}
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elem->type |= type;
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out:
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up(&debug_list_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_dynamic_debug_module);
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int __dynamic_dbg_enabled_helper(char *mod_name, int type, int value, int hash)
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{
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struct debug_name *elem;
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int ret = 0;
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if (dynamic_enabled == DYNAMIC_ENABLED_ALL)
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return 1;
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rcu_read_lock();
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elem = find_debug_module_hash(mod_name, hash);
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if (elem && elem->enable)
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ret = 1;
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL_GPL(__dynamic_dbg_enabled_helper);
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static void set_all(bool enable)
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{
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struct debug_name *e;
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struct hlist_node *node;
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int i;
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long long enable_mask;
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for (i = 0; i < DEBUG_HASH_TABLE_SIZE; i++) {
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if (module_table[i].first != NULL) {
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hlist_for_each_entry(e, node, &module_table[i], hlist) {
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e->enable = enable;
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}
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}
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}
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if (enable)
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enable_mask = ULLONG_MAX;
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else
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enable_mask = 0;
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dynamic_printk_enabled = enable_mask;
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dynamic_printk_enabled2 = enable_mask;
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}
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static int disabled_hash(int i, bool first_table)
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{
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struct debug_name *e;
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struct hlist_node *node;
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if (first_table) {
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hlist_for_each_entry(e, node, &module_table[i], hlist) {
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if (e->enable)
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return 0;
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}
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} else {
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hlist_for_each_entry(e, node, &module_table2[i], hlist2) {
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if (e->enable)
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return 0;
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}
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}
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return 1;
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}
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static ssize_t pr_debug_write(struct file *file, const char __user *buf,
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size_t length, loff_t *ppos)
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{
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char *buffer, *s, *value_str, *setting_str;
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int err, value;
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struct debug_name *elem = NULL;
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int all = 0;
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if (length > PAGE_SIZE || length < 0)
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return -EINVAL;
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buffer = (char *)__get_free_page(GFP_KERNEL);
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if (!buffer)
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return -ENOMEM;
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err = -EFAULT;
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if (copy_from_user(buffer, buf, length))
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goto out;
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err = -EINVAL;
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if (length < PAGE_SIZE)
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buffer[length] = '\0';
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else if (buffer[PAGE_SIZE-1])
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goto out;
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err = -EINVAL;
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down(&debug_list_mutex);
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if (strncmp("set", buffer, 3))
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goto out_up;
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s = buffer + 3;
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setting_str = strsep(&s, "=");
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if (s == NULL)
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goto out_up;
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setting_str = strstrip(setting_str);
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value_str = strsep(&s, " ");
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if (s == NULL)
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goto out_up;
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s = strstrip(s);
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if (!strncmp(s, "all", 3))
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all = 1;
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else
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elem = find_debug_module(s);
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if (!strncmp(setting_str, "enable", 6)) {
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value = !!simple_strtol(value_str, NULL, 10);
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if (all) {
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if (value) {
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set_all(true);
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num_enabled = nr_entries;
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dynamic_enabled = DYNAMIC_ENABLED_ALL;
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} else {
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set_all(false);
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num_enabled = 0;
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dynamic_enabled = DYNAMIC_ENABLED_NONE;
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}
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err = 0;
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} else if (elem) {
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if (value && (elem->enable == 0)) {
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dynamic_printk_enabled |= (1LL << elem->hash1);
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dynamic_printk_enabled2 |= (1LL << elem->hash2);
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elem->enable = 1;
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num_enabled++;
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dynamic_enabled = DYNAMIC_ENABLED_SOME;
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err = 0;
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printk(KERN_DEBUG
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"debugging enabled for module %s\n",
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elem->name);
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} else if (!value && (elem->enable == 1)) {
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elem->enable = 0;
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num_enabled--;
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if (disabled_hash(elem->hash1, true))
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dynamic_printk_enabled &=
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~(1LL << elem->hash1);
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if (disabled_hash(elem->hash2, false))
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dynamic_printk_enabled2 &=
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~(1LL << elem->hash2);
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if (num_enabled)
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dynamic_enabled = DYNAMIC_ENABLED_SOME;
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else
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dynamic_enabled = DYNAMIC_ENABLED_NONE;
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err = 0;
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printk(KERN_DEBUG
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"debugging disabled for module %s\n",
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elem->name);
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}
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}
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}
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if (!err)
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err = length;
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out_up:
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up(&debug_list_mutex);
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out:
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free_page((unsigned long)buffer);
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return err;
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}
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static void *pr_debug_seq_start(struct seq_file *f, loff_t *pos)
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{
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return (*pos < DEBUG_HASH_TABLE_SIZE) ? pos : NULL;
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}
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static void *pr_debug_seq_next(struct seq_file *s, void *v, loff_t *pos)
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{
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(*pos)++;
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if (*pos >= DEBUG_HASH_TABLE_SIZE)
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return NULL;
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return pos;
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}
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static void pr_debug_seq_stop(struct seq_file *s, void *v)
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{
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/* Nothing to do */
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}
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static int pr_debug_seq_show(struct seq_file *s, void *v)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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struct debug_name *elem;
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unsigned int i = *(loff_t *) v;
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rcu_read_lock();
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head = &module_table[i];
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hlist_for_each_entry_rcu(elem, node, head, hlist) {
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seq_printf(s, "%s enabled=%d", elem->name, elem->enable);
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seq_printf(s, "\n");
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}
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rcu_read_unlock();
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return 0;
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}
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static struct seq_operations pr_debug_seq_ops = {
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.start = pr_debug_seq_start,
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.next = pr_debug_seq_next,
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.stop = pr_debug_seq_stop,
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.show = pr_debug_seq_show
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};
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static int pr_debug_open(struct inode *inode, struct file *filp)
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{
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return seq_open(filp, &pr_debug_seq_ops);
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}
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static const struct file_operations pr_debug_operations = {
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.open = pr_debug_open,
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.read = seq_read,
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.write = pr_debug_write,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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static int __init dynamic_printk_init(void)
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{
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struct dentry *dir, *file;
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struct mod_debug *iter;
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unsigned long value;
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dir = debugfs_create_dir("dynamic_printk", NULL);
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if (!dir)
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return -ENOMEM;
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file = debugfs_create_file("modules", 0644, dir, NULL,
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&pr_debug_operations);
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if (!file) {
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debugfs_remove(dir);
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return -ENOMEM;
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}
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for (value = (unsigned long)__start___verbose;
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value < (unsigned long)__stop___verbose;
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value += sizeof(struct mod_debug)) {
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iter = (struct mod_debug *)value;
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register_dynamic_debug_module(iter->modname,
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iter->type,
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iter->logical_modname,
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iter->flag_names, iter->hash, iter->hash2);
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}
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if (dynamic_enabled == DYNAMIC_ENABLED_ALL)
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set_all(true);
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return 0;
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}
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module_init(dynamic_printk_init);
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/* may want to move this earlier so we can get traces as early as possible */
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static int __init dynamic_printk_setup(char *str)
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{
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if (str)
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return -ENOENT;
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dynamic_enabled = DYNAMIC_ENABLED_ALL;
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return 0;
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}
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/* Use early_param(), so we can get debug output as early as possible */
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early_param("dynamic_printk", dynamic_printk_setup);
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