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authorLinus Torvalds <torvalds@linux-foundation.org>2010-06-05 11:17:36 -0600
committerRusty Russell <rusty@rustcorp.com.au>2010-06-05 11:17:37 +0930
commit3bafeb6247042dcbb72b0141ec7c7107de9f0b99 (patch)
treef9b8f2437455332cd64d94bedb0836ac0f2b6fd9 /kernel/module.c
parent75676500f8298f0ee89db12db97294883c4b768e (diff)
module: move find_module check to end
I think Rusty may have made the lock a bit _too_ finegrained there, and didn't add it to some places that needed it. It looks, for example, like PATCH 1/2 actually drops the lock in places where it's needed ("find_module()" is documented to need it, but now load_module() didn't hold it at all when it did the find_module()). Rather than adding a new "module_loading" list, I think we should be able to just use the existing "modules" list, and just fix up the locking a bit. In fact, maybe we could just move the "look up existing module" a bit later - optimistically assuming that the module doesn't exist, and then just undoing the work if it turns out that we were wrong, just before adding ourselves to the list. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel/module.c')
-rw-r--r--kernel/module.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/module.c b/kernel/module.c
index d293c213c22c..28450047852a 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2226,11 +2226,6 @@ static noinline struct module *load_module(void __user *umod,
goto free_mod;
}
- if (find_module(mod->name)) {
- err = -EEXIST;
- goto free_mod;
- }
-
mod->state = MODULE_STATE_COMING;
/* Allow arches to frob section contents and sizes. */
@@ -2509,6 +2504,12 @@ static noinline struct module *load_module(void __user *umod,
* The mutex protects against concurrent writers.
*/
mutex_lock(&module_mutex);
+ if (find_module(mod->name)) {
+ err = -EEXIST;
+ /* This will also unlock the mutex */
+ goto already_exists;
+ }
+
list_add_rcu(&mod->list, &modules);
mutex_unlock(&module_mutex);
@@ -2535,6 +2536,7 @@ static noinline struct module *load_module(void __user *umod,
mutex_lock(&module_mutex);
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
+ already_exists:
mutex_unlock(&module_mutex);
synchronize_sched();
module_arch_cleanup(mod);

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