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kmod/core: account for failing modules in notifier #816

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Merged
joe-lawrence merged 1 commit into from
Apr 11, 2018
Merged

kmod/core: account for failing modules in notifier #816

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77 changes: 68 additions & 9 deletions kmod/core/core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -330,7 +330,7 @@ static inline void post_patch_callback(struct kpatch_object *object)
(*object->post_patch_callback)(object);
}

static inline void pre_unpatch_callbacks(struct kpatch_object *object)
static inline void pre_unpatch_callback(struct kpatch_object *object)
{
if (kpatch_object_linked(object) &&
object->pre_unpatch_callback &&
Expand Down Expand Up @@ -424,7 +424,7 @@ static int kpatch_remove_patch(void *data)

/* run any user-defined pre-unpatch callbacks */
list_for_each_entry(object, &kpmod->objects, list)
pre_unpatch_callbacks(object);
pre_unpatch_callback(object);

/* Check if any inconsistent NMI has happened while updating */
ret = kpatch_state_finish(KPATCH_STATE_SUCCESS);
Expand Down Expand Up @@ -783,8 +783,10 @@ static int kpatch_unlink_object(struct kpatch_object *object)
}
}

if (object->mod)
if (object->mod) {
module_put(object->mod);
object->mod = NULL;
}

return 0;
}
Expand Down Expand Up @@ -861,8 +863,8 @@ static int kpatch_link_object(struct kpatch_module *kpmod,
return ret;
}

static int kpatch_module_notify(struct notifier_block *nb, unsigned long action,
void *data)
static int kpatch_module_notify_coming(struct notifier_block *nb,
unsigned long action, void *data)
{
struct module *mod = data;
struct kpatch_module *kpmod;
Expand Down Expand Up @@ -917,6 +919,53 @@ static int kpatch_module_notify(struct notifier_block *nb, unsigned long action,
/* no way to stop the module load on error */
WARN(ret, "error (%d) patching newly loaded module '%s'\n", ret,
object->name);

return 0;
}

static int kpatch_module_notify_going(struct notifier_block *nb,
unsigned long action, void *data)
{
struct module *mod = data;
struct kpatch_module *kpmod;
struct kpatch_object *object;
struct kpatch_func *func;
bool found = false;

if (action != MODULE_STATE_GOING)
return 0;

down(&kpatch_mutex);

list_for_each_entry(kpmod, &kpmod_list, list) {
list_for_each_entry(object, &kpmod->objects, list) {
if (!kpatch_object_linked(object))
continue;
if (!strcmp(object->name, mod->name)) {
found = true;
goto done;
}
}
}
done:
if (!found)
goto out;

/* run user-defined pre-unpatch callback */
pre_unpatch_callback(object);

/* remove from the global func hash */
list_for_each_entry(func, &object->funcs, list)
hash_del_rcu(&func->node);

/* run user-defined pre-unpatch callback */
post_unpatch_callback(object);

kpatch_unlink_object(object);

out:
up(&kpatch_mutex);

return 0;
}

Expand Down Expand Up @@ -1164,10 +1213,14 @@ int kpatch_unregister(struct kpatch_module *kpmod)
EXPORT_SYMBOL(kpatch_unregister);


static struct notifier_block kpatch_module_nb = {
.notifier_call = kpatch_module_notify,
static struct notifier_block kpatch_module_nb_coming = {
.notifier_call = kpatch_module_notify_coming,
.priority = INT_MIN, /* called last */
};
static struct notifier_block kpatch_module_nb_going = {
.notifier_call = kpatch_module_notify_going,
.priority = INT_MAX, /* called first */
};

static int kpatch_init(void)
{
Expand All @@ -1189,12 +1242,17 @@ static int kpatch_init(void)
if (!kpatch_root_kobj)
return -ENOMEM;

ret = register_module_notifier(&kpatch_module_nb);
ret = register_module_notifier(&kpatch_module_nb_coming);
if (ret)
goto err_root_kobj;
ret = register_module_notifier(&kpatch_module_nb_going);
if (ret)
goto err_unregister_coming;

return 0;

err_unregister_coming:
WARN_ON(unregister_module_notifier(&kpatch_module_nb_coming));
err_root_kobj:
kobject_put(kpatch_root_kobj);
return ret;
Expand All @@ -1205,7 +1263,8 @@ static void kpatch_exit(void)
rcu_barrier();

WARN_ON(kpatch_num_patched != 0);
WARN_ON(unregister_module_notifier(&kpatch_module_nb));
WARN_ON(unregister_module_notifier(&kpatch_module_nb_coming));
WARN_ON(unregister_module_notifier(&kpatch_module_nb_going));
kobject_put(kpatch_root_kobj);
}

Expand Down