module.c: allow modules to enter themselves during mod init

kernel/module.c

@@ -1058,6 +1058,15 @@ sys_init_module(void *umod,
 	list_add(&mod->extable.list, &extables);
 	spin_unlock_irq(&modlist_lock);
 
+	/* Note, setting the mod->live to 1 here is safe because we haven't
+	 * linked the module into the system's kernel symbol table yet,
+	 * which means that the only way any other kernel code can call
+	 * into this module right now is if this module hands out entry
+	 * pointers to the other code.  We assume that no module hands out
+	 * entry pointers to the rest of the kernel unless it is ready to
+	 * have them used.
+	 */
+	mod->live = 1;
 	/* Start the module */
 	ret = mod->init ? mod->init() : 0;
 	if (ret < 0) {
@@ -1070,9 +1079,10 @@ sys_init_module(void *umod,
 			/* Mark it "live" so that they can force
 			   deletion later, and we don't keep getting
 			   woken on every decrement. */
-			mod->live = 1;
-		} else
+		} else {
+			mod->live = 0;
 			free_module(mod);
+		}
 		up(&module_mutex);
 		return ret;
 	}
@@ -1087,7 +1097,6 @@ sys_init_module(void *umod,
 	mod->module_init = NULL;
 
 	/* All ok! */
-	mod->live = 1;
 	up(&module_mutex);
 	return 0;
 }