livepatch: Remove custom kobject state handling

kobject_init() always succeeds and sets the reference count to 1.
It allows to always free the structures via kobject_put() and
the related release callback.

Note that the custom kobject state handling was used only
because we did not know that kobject_put() can and actually
should get called even when kobject_init_and_add() fails.

The patch should not change the existing behavior.

Suggested-by: "Tobin C. Harding" <tobin@kernel.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 53551f4707223af3933e3f2a4f58eee926d82091..a14bab1a0a3e979a105674785cba7853e09fe0eb 100644 (file)
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -86,7 +86,6 @@ struct klp_func {
        struct list_head node;
        struct list_head stack_node;
        unsigned long old_size, new_size;
-       bool kobj_added;
        bool nop;
        bool patched;
        bool transition;
@@ -141,7 +140,6 @@ struct klp_object {
        struct list_head func_list;
        struct list_head node;
        struct module *mod;
-       bool kobj_added;
        bool dynamic;
        bool patched;
 };
@@ -170,7 +168,6 @@ struct klp_patch {
        struct list_head list;
        struct kobject kobj;
        struct list_head obj_list;
-       bool kobj_added;
        bool enabled;
        bool forced;
        struct work_struct free_work;

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 14f33ab6c583ced8362e94b008893fdc7d075794..42385f23252a258b50d424c1ae749f8b225483ba 100644 (file)
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -426,6 +426,9 @@ static void klp_free_object_dynamic(struct klp_object *obj)
        kfree(obj);
 }
 
+static struct kobj_type klp_ktype_object;
+static struct kobj_type klp_ktype_func;
+
 static struct klp_object *klp_alloc_object_dynamic(const char *name)
 {
        struct klp_object *obj;
@@ -443,6 +446,7 @@ static struct klp_object *klp_alloc_object_dynamic(const char *name)
        }
 
        INIT_LIST_HEAD(&obj->func_list);
+       kobject_init(&obj->kobj, &klp_ktype_object);
        obj->dynamic = true;
 
        return obj;
@@ -471,6 +475,7 @@ static struct klp_func *klp_alloc_func_nop(struct klp_func *old_func,
                }
        }
 
+       kobject_init(&func->kobj, &klp_ktype_func);
        /*
         * func->new_func is same as func->old_func. These addresses are
         * set when the object is loaded, see klp_init_object_loaded().
@@ -588,13 +593,7 @@ static void __klp_free_funcs(struct klp_object *obj, bool nops_only)
                        continue;
 
                list_del(&func->node);
-
-               /* Might be called from klp_init_patch() error path. */
-               if (func->kobj_added) {
-                       kobject_put(&func->kobj);
-               } else if (func->nop) {
-                       klp_free_func_nop(func);
-               }
+               kobject_put(&func->kobj);
        }
 }
 
@@ -624,13 +623,7 @@ static void __klp_free_objects(struct klp_patch *patch, bool nops_only)
                        continue;
 
                list_del(&obj->node);
-
-               /* Might be called from klp_init_patch() error path. */
-               if (obj->kobj_added) {
-                       kobject_put(&obj->kobj);
-               } else if (obj->dynamic) {
-                       klp_free_object_dynamic(obj);
-               }
+               kobject_put(&obj->kobj);
        }
 }
 
@@ -675,10 +668,8 @@ static void klp_free_patch_finish(struct klp_patch *patch)
         * this is called when the patch gets disabled and it
         * cannot get enabled again.
         */
-       if (patch->kobj_added) {
-               kobject_put(&patch->kobj);
-               wait_for_completion(&patch->finish);
-       }
+       kobject_put(&patch->kobj);
+       wait_for_completion(&patch->finish);
 
        /* Put the module after the last access to struct klp_patch. */
        if (!patch->forced)
@@ -700,8 +691,6 @@ static void klp_free_patch_work_fn(struct work_struct *work)
 
 static int klp_init_func(struct klp_object *obj, struct klp_func *func)
 {
-       int ret;
-
        if (!func->old_name)
                return -EINVAL;
 
@@ -724,13 +713,9 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
         * object. If the user selects 0 for old_sympos, then 1 will be used
         * since a unique symbol will be the first occurrence.
         */
-       ret = kobject_init_and_add(&func->kobj, &klp_ktype_func,
-                                  &obj->kobj, "%s,%lu", func->old_name,
-                                  func->old_sympos ? func->old_sympos : 1);
-       if (!ret)
-               func->kobj_added = true;
-
-       return ret;
+       return kobject_add(&func->kobj, &obj->kobj, "%s,%lu",
+                          func->old_name,
+                          func->old_sympos ? func->old_sympos : 1);
 }
 
 /* Arches may override this to finish any remaining arch-specific tasks */
@@ -801,11 +786,9 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
        klp_find_object_module(obj);
 
        name = klp_is_module(obj) ? obj->name : "vmlinux";
-       ret = kobject_init_and_add(&obj->kobj, &klp_ktype_object,
-                                  &patch->kobj, "%s", name);
+       ret = kobject_add(&obj->kobj, &patch->kobj, "%s", name);
        if (ret)
                return ret;
-       obj->kobj_added = true;
 
        klp_for_each_func(obj, func) {
                ret = klp_init_func(obj, func);
@@ -829,7 +812,7 @@ static int klp_init_patch_early(struct klp_patch *patch)
 
        INIT_LIST_HEAD(&patch->list);
        INIT_LIST_HEAD(&patch->obj_list);
-       patch->kobj_added = false;
+       kobject_init(&patch->kobj, &klp_ktype_patch);
        patch->enabled = false;
        patch->forced = false;
        INIT_WORK(&patch->free_work, klp_free_patch_work_fn);
@@ -840,11 +823,11 @@ static int klp_init_patch_early(struct klp_patch *patch)
                        return -EINVAL;
 
                INIT_LIST_HEAD(&obj->func_list);
-               obj->kobj_added = false;
+               kobject_init(&obj->kobj, &klp_ktype_object);
                list_add_tail(&obj->node, &patch->obj_list);
 
                klp_for_each_func_static(obj, func) {
-                       func->kobj_added = false;
+                       kobject_init(&func->kobj, &klp_ktype_func);
                        list_add_tail(&func->node, &obj->func_list);
                }
        }
@@ -860,11 +843,9 @@ static int klp_init_patch(struct klp_patch *patch)
        struct klp_object *obj;
        int ret;
 
-       ret = kobject_init_and_add(&patch->kobj, &klp_ktype_patch,
-                                  klp_root_kobj, "%s", patch->mod->name);
+       ret = kobject_add(&patch->kobj, klp_root_kobj, "%s", patch->mod->name);
        if (ret)
                return ret;
-       patch->kobj_added = true;
 
        if (patch->replace) {
                ret = klp_add_nops(patch);
@@ -926,9 +907,6 @@ static int __klp_enable_patch(struct klp_patch *patch)
        if (WARN_ON(patch->enabled))
                return -EINVAL;
 
-       if (!patch->kobj_added)
-               return -EINVAL;
-
        pr_notice("enabling patch '%s'\n", patch->mod->name);
 
        klp_init_transition(patch, KLP_PATCHED);