module: fix symbol waiting when module fails before init (6f13909f) · Commits · 戴 / test

We use resolve_symbol_wait(), which blocks if the module containing the symbol is still loading. However: 1) The module_wq we use is only woken after calling the modules' init function, but there are other failure paths after the module is placed in the linked list where we need to do the same thing. 2) wake_up() only wakes one waiter, and our waitqueue is shared by all modules, so we need to wake them all. 3) wake_up_all() doesn't imply a memory barrier: I feel happier calling it after we've grabbed and dropped the module_mutex, not just after the state assignment. Signed-off-by:

Rusty Russell <rusty@rustcorp.com.au>

kernel/module.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -2959,7 +2959,7 @@ static struct module load_module(void __user umod,
		/* Unlink carefully: kallsyms could be walking list. */
		list_del_rcu(&mod->list);
		module_bug_cleanup(mod);

		wake_up_all(&module_wq);
		ddebug:
		dynamic_debug_remove(info.debug);
		unlock:
		@@ -3034,7 +3034,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
		blocking_notifier_call_chain(&module_notify_list,
		MODULE_STATE_GOING, mod);
		free_module(mod);
		wake_up(&module_wq);
		wake_up_all(&module_wq);
		return ret;
		}
		if (ret > 0) {
		@@ -3046,9 +3046,8 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
		dump_stack();
		}

		/* Now it's a first class citizen! Wake up anyone waiting for it. */
		/* Now it's a first class citizen! */
		mod->state = MODULE_STATE_LIVE;
		wake_up(&module_wq);
		blocking_notifier_call_chain(&module_notify_list,
		MODULE_STATE_LIVE, mod);

		@@ -3071,6 +3070,7 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
		mod->init_ro_size = 0;
		mod->init_text_size = 0;
		mutex_unlock(&module_mutex);
		wake_up_all(&module_wq);

		return 0;
		}

Admin message