module: refactor load_module part 4

Allocate references inside module_unload_init(), clean up inside
module_unload_free().

This version fixed to do allocation before __this_cpu_write, thanks to
bug reports from linux-next from Dave Young <hidave.darkstar@gmail.com>
and Stephen Rothwell <sfr@canb.auug.org.au>.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/kernel/module.c b/kernel/module.c
index d8faf35..241bc41 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -524,8 +524,12 @@ static char last_unloaded_module[MODULE_NAME_LEN+1];
 EXPORT_TRACEPOINT_SYMBOL(module_get);
 
 /* Init the unload section of the module. */
-static void module_unload_init(struct module *mod)
+static int module_unload_init(struct module *mod)
 {
+       mod->refptr = alloc_percpu(struct module_ref);
+       if (!mod->refptr)
+               return -ENOMEM;
+
        INIT_LIST_HEAD(&mod->source_list);
        INIT_LIST_HEAD(&mod->target_list);
 
@@ -533,6 +537,8 @@ static void module_unload_init(struct module *mod)
        __this_cpu_write(mod->refptr->incs, 1);
        /* Backwards compatibility macros put refcount during init. */
        mod->waiter = current;
+
+       return 0;
 }
 
 /* Does a already use b? */
@@ -612,6 +618,8 @@ static void module_unload_free(struct module *mod)
                kfree(use);
        }
        mutex_unlock(&module_mutex);
+
+       free_percpu(mod->refptr);
 }
 
 #ifdef CONFIG_MODULE_FORCE_UNLOAD
@@ -885,8 +893,9 @@ int ref_module(struct module *a, struct module *b)
 }
 EXPORT_SYMBOL_GPL(ref_module);
 
-static inline void module_unload_init(struct module *mod)
+static inline int module_unload_init(struct module *mod)
 {
+       return 0;
 }
 #endif /* CONFIG_MODULE_UNLOAD */
 
@@ -1559,10 +1568,7 @@ static void free_module(struct module *mod)
        module_free(mod, mod->module_init);
        kfree(mod->args);
        percpu_modfree(mod);
-#if defined(CONFIG_MODULE_UNLOAD)
-       if (mod->refptr)
-               free_percpu(mod->refptr);
-#endif
+
        /* Free lock-classes: */
        lockdep_free_key_range(mod->module_core, mod->core_size);
 
@@ -2442,15 +2448,10 @@ static noinline struct module *load_module(void __user *umod,
                goto free_percpu;
        }
 
-#if defined(CONFIG_MODULE_UNLOAD)
-       mod->refptr = alloc_percpu(struct module_ref);
-       if (!mod->refptr) {
-               err = -ENOMEM;
-               goto free_init;
-       }
-#endif
        /* Now we've moved module, initialize linked lists, etc. */
-       module_unload_init(mod);
+       err = module_unload_init(mod);
+       if (err)
+               goto free_init;
 
        /* Set up license info based on the info section */
        set_license(mod, get_modinfo(sechdrs, infoindex, "license"));
@@ -2619,10 +2620,7 @@ static noinline struct module *load_module(void __user *umod,
  cleanup:
        free_modinfo(mod);
        module_unload_free(mod);
-#if defined(CONFIG_MODULE_UNLOAD)
-       free_percpu(mod->refptr);
  free_init:
-#endif
        module_free(mod, mod->module_init);
        module_free(mod, mod->module_core);
        /* mod will be freed with core. Don't access it beyond this line! */