lkml.org 
[lkml]   [2012]   [Mar]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/7] module: take rcu_read_lock_sched for find_module
Date
Similar to find_symbol(), find_module() also iterates module list,
should use list_for_each_entry_rcu() too, thus its callers should
hold rcu_read_lock_sched before calling it.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
kernel/module.c | 42 +++++++++++++++++++++++-------------------
1 files changed, 23 insertions(+), 19 deletions(-)
diff --git a/kernel/module.c b/kernel/module.c
index b31b23f..f210d74 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -413,7 +413,7 @@ struct module *find_module(const char *name)
{
struct module *mod;

- list_for_each_entry(mod, &modules, list) {
+ list_for_each_entry_rcu(mod, &modules, list) {
if (strcmp(mod->name, name) == 0)
return mod;
}
@@ -778,14 +778,16 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
return -EFAULT;
name[MODULE_NAME_LEN-1] = '\0';

- if (mutex_lock_interruptible(&module_mutex) != 0)
- return -EINTR;
-
+ rcu_read_lock_sched();
mod = find_module(name);
if (!mod) {
- ret = -ENOENT;
- goto out;
+ rcu_read_unlock_sched();
+ return -ENOENT;
}
+ rcu_read_unlock_sched();
+
+ if (mutex_lock_interruptible(&module_mutex) != 0)
+ return -EINTR;

if (!list_empty(&mod->source_list)) {
/* Other modules depend on us: get rid of them first. */
@@ -2899,18 +2901,13 @@ static struct module *load_module(void __user *umod,
/* Mark state as coming so strong_try_module_get() ignores us. */
mod->state = MODULE_STATE_COMING;

- /* Now sew it into the lists so we can get lockdep and oops
- * info during argument parsing. No one should access us, since
- * strong_try_module_get() will fail.
- * lockdep/oops can run asynchronous, so use the RCU list insertion
- * function to insert in a way safe to concurrent readers.
- * The mutex protects against concurrent writers.
- */
- mutex_lock(&module_mutex);
+ rcu_read_lock_sched();
if (find_module(mod->name)) {
err = -EEXIST;
- goto unlock;
+ rcu_read_unlock_sched();
+ goto free_args;
}
+ rcu_read_unlock_sched();

/* This has to be done once we're sure module name is unique. */
dynamic_debug_setup(info.debug, info.num_debug);
@@ -2920,6 +2917,14 @@ static struct module *load_module(void __user *umod,
if (err < 0)
goto ddebug;

+ /* Now sew it into the lists so we can get lockdep and oops
+ * info during argument parsing. No one should access us, since
+ * strong_try_module_get() will fail.
+ * lockdep/oops can run asynchronous, so use the RCU list insertion
+ * function to insert in a way safe to concurrent readers.
+ * The mutex protects against concurrent writers.
+ */
+ mutex_lock(&module_mutex);
module_bug_finalize(info.hdr, info.sechdrs, mod);
list_add_rcu(&mod->list, &modules);
mutex_unlock(&module_mutex);
@@ -2946,12 +2951,11 @@ static struct module *load_module(void __user *umod,
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
module_bug_cleanup(mod);
-
- ddebug:
- dynamic_debug_remove(info.debug);
- unlock:
mutex_unlock(&module_mutex);
synchronize_sched();
+ ddebug:
+ dynamic_debug_remove(info.debug);
+ free_args:
kfree(mod->args);
free_arch_cleanup:
module_arch_cleanup(mod);
--
1.7.7.6


\
 
 \ /
  Last update: 2012-03-15 15:53    [from the cache]
©2003-2011 Jasper Spaans