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" <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>
---
include/linux/livepatch.h | 3 ---
kernel/livepatch/core.c | 56 ++++++++++++++---------------------------------
2 files changed, 17 insertions(+), 42 deletions(-)
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 53551f470722..a14bab1a0a3e 100644
--- 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 eb0ee10a1981..1ff91f7cbafb 100644
--- 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);
--
2.16.4
On Fri, May 03, 2019 at 03:26:24PM +0200, Petr Mladek wrote:
> 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" <[email protected]>
> Signed-off-by: Petr Mladek <[email protected]>
> ---
> include/linux/livepatch.h | 3 ---
> kernel/livepatch/core.c | 56 ++++++++++++++---------------------------------
> 2 files changed, 17 insertions(+), 42 deletions(-)
>
> diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
> index 53551f470722..a14bab1a0a3e 100644
> --- 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;
Minor nitpick, the description of kobj_added needs to be removed from
structure descriptions.
Reviewed-by: Kamalesh Babulal <[email protected]>
--
Kamalesh
On Fri, 3 May 2019, Petr Mladek wrote:
> 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.
Pity that the changelog does not describe the change from
kobject_init_and_add() to two-stage kobject init (separate kobject_init()
and kobject_add()).
Petr changed it, because now each member of new dynamic lists (created in
klp_init_patch_early()) is initialized with kobject_init(), so we do not
have to worry about calling kobject_put() (this is slightly different from
kobj_added).
It would also be possible to retain kobject_init_and_add() and move it to
klp_init_patch_early(), but it would be uglier in my opinion.
Miroslav
On Tue, May 07, 2019 at 02:32:57PM +0200, Miroslav Benes wrote:
> On Fri, 3 May 2019, Petr Mladek wrote:
>
> > 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.
>
> Pity that the changelog does not describe the change from
> kobject_init_and_add() to two-stage kobject init (separate kobject_init()
> and kobject_add()).
>
> Petr changed it, because now each member of new dynamic lists (created in
> klp_init_patch_early()) is initialized with kobject_init(), so we do not
> have to worry about calling kobject_put() (this is slightly different from
> kobj_added).
>
> It would also be possible to retain kobject_init_and_add() and move it to
> klp_init_patch_early(), but it would be uglier in my opinion.
kobject_init_and_add() is only there for the "simple" use cases.
There's no problem with doing the two-stage process on your own like
this, that's exactly what it is there for :)
thanks,
greg k-h