linux-kernel - [PATCH 07/10] module: _

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Date:	Wed, 24 Feb 2010 21:04:03 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	paulmck@...ux.vnet.ibm.com
Cc:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-kernel@...r.kernel.org, mingo@...e.hu, laijs@...fujitsu.com,
	dipankar@...ibm.com, akpm@...ux-foundation.org,
	josh@...htriplett.org, dvhltc@...ibm.com, niv@...ibm.com,
	tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
	Valdis.Kletnieks@...edu, dhowells@...hat.com
Subject: [PATCH 07/10] module: __rcu annotations

These are partial, because the modules list is used
inconsistently with RCU. We actually pass a list_head
of an RCU protected list into another function.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 include/linux/module.h |    4 ++--
 kernel/module.c        |   20 +++++++++++++-------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 6cb1a3c..94ce22e 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -6,7 +6,7 @@
  * Rewritten by Richard Henderson <rth@...u.edu> Dec 1996
  * Rewritten again by Rusty Russell, 2002
  */
-#include <linux/list.h>
+#include <linux/rculist.h>
 #include <linux/stat.h>
 #include <linux/compiler.h>
 #include <linux/cache.h>
@@ -238,7 +238,7 @@ struct module
 	enum module_state state;
 
 	/* Member of list of modules */
-	struct list_head list;
+	struct rcu_list_head list;
 
 	/* Unique handle for this module */
 	char name[MODULE_NAME_LEN];
diff --git a/kernel/module.c b/kernel/module.c
index f82386b..d8b7603 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -78,7 +78,7 @@ EXPORT_TRACEPOINT_SYMBOL(module_get);
  * (delete uses stop_machine/add uses RCU list operations). */
 DEFINE_MUTEX(module_mutex);
 EXPORT_SYMBOL_GPL(module_mutex);
-static LIST_HEAD(modules);
+static LIST_HEAD_RCU(modules);
 
 /* Block module loading/unloading? */
 int modules_disabled = 0;
@@ -360,10 +360,12 @@ struct module *find_module(const char *name)
 {
 	struct module *mod;
 
-	list_for_each_entry(mod, &modules, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(mod, &modules, list) {
 		if (strcmp(mod->name, name) == 0)
 			return mod;
 	}
+	rcu_read_unlock();
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(find_module);
@@ -544,7 +546,8 @@ static void module_unload_free(struct module *mod)
 {
 	struct module *i;
 
-	list_for_each_entry(i, &modules, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(i, &modules, list) {
 		struct module_use *use;
 
 		list_for_each_entry(use, &i->modules_which_use_me, list) {
@@ -559,6 +562,7 @@ static void module_unload_free(struct module *mod)
 			}
 		}
 	}
+	rcu_read_unlock();
 }
 
 #ifdef CONFIG_MODULE_FORCE_UNLOAD
@@ -1368,7 +1372,7 @@ static void mod_kobject_remove(struct module *mod)
 static int __unlink_module(void *_mod)
 {
 	struct module *mod = _mod;
-	list_del(&mod->list);
+	list_del_rcu(&mod->list);
 	return 0;
 }
 
@@ -2718,7 +2722,8 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
 	unsigned int i;
 	int ret;
 
-	list_for_each_entry(mod, &modules, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(mod, &modules, list) {
 		for (i = 0; i < mod->num_symtab; i++) {
 			ret = fn(data, mod->strtab + mod->symtab[i].st_name,
 				 mod, mod->symtab[i].st_value);
@@ -2726,6 +2731,7 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
 				return ret;
 		}
 	}
+	rcu_read_unlock();
 	return 0;
 }
 #endif /* CONFIG_KALLSYMS */
@@ -2768,12 +2774,12 @@ static char *module_flags(struct module *mod, char *buf)
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
 	mutex_lock(&module_mutex);
-	return seq_list_start(&modules, *pos);
+	return seq_list_start((struct list_head *)&modules, *pos);
 }
 
 static void *m_next(struct seq_file *m, void *p, loff_t *pos)
 {
-	return seq_list_next(p, &modules, pos);
+	return seq_list_next(p, (struct list_head *)&modules, pos);
 }
 
 static void m_stop(struct seq_file *m, void *p)
-- 
1.6.3.3

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