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livepatch: Remove custom kobject state handling

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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>
This commit is contained in:
Petr Mladek 2019-05-03 15:26:24 +02:00 committed by Jiri Kosina
parent 31adf2308f
commit 4d141ab341
2 changed files with 17 additions and 42 deletions
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3
include/linux/livepatch.h
View File

@ -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;

56
kernel/livepatch/core.c
View File

@ -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);