module: fix symbol waiting when module fails before init

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>

diff --git a/kernel/module.c b/kernel/module.c
index 7f2ee45f362c5a59de4c07a24ff52507451421ce..63cf6e7f1394aa9e64fa14216911d56b7d03473e 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -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;
 }