[PATCH v1 19/19] livepatch: Remove obsolete per-object callbacks

[Petr Mladek <pmladek@suse.com>]

This commit removes the obsolete per-object callbacks from the livepatch
framework.  All selftests have been migrated to the new per-state
callbacks, making the per-object callbacks redundant.

Instead, use the new per-state callbacks. They offer improved semantics
by associating callbacks and shadow variables with a specific state,
enabling better lifetime management of changes.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 include/linux/livepatch.h     | 26 --------------------------
 kernel/livepatch/core.c       | 29 -----------------------------
 kernel/livepatch/core.h       | 33 ---------------------------------
 kernel/livepatch/transition.c |  9 ---------
 4 files changed, 97 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index d02d7a616338..428300181af3 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -77,35 +77,10 @@ struct klp_func {
 	bool transition;
 };
 
-struct klp_object;
-
-/**
- * struct klp_callbacks - pre/post live-(un)patch callback structure
- * @pre_patch:		executed before code patching
- * @post_patch:		executed after code patching
- * @pre_unpatch:	executed before code unpatching
- * @post_unpatch:	executed after code unpatching
- * @post_unpatch_enabled:	flag indicating if post-unpatch callback
- * 				should run
- *
- * All callbacks are optional.  Only the pre-patch callback, if provided,
- * will be unconditionally executed.  If the parent klp_object fails to
- * patch for any reason, including a non-zero error status returned from
- * the pre-patch callback, no further callbacks will be executed.
- */
-struct klp_callbacks {
-	int (*pre_patch)(struct klp_object *obj);
-	void (*post_patch)(struct klp_object *obj);
-	void (*pre_unpatch)(struct klp_object *obj);
-	void (*post_unpatch)(struct klp_object *obj);
-	bool post_unpatch_enabled;
-};
-
 /**
  * struct klp_object - kernel object structure for live patching
  * @name:	module name (or NULL for vmlinux)
  * @funcs:	function entries for functions to be patched in the object
- * @callbacks:	functions to be executed pre/post (un)patching
  * @kobj:	kobject for sysfs resources
  * @func_list:	dynamic list of the function entries
  * @node:	list node for klp_patch obj_list
@@ -118,7 +93,6 @@ struct klp_object {
 	/* external */
 	const char *name;
 	struct klp_func *funcs;
-	struct klp_callbacks callbacks;
 
 	/* internal */
 	struct kobject kobj;
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 4d244eef0e53..3d6b8edb3e2b 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -983,8 +983,6 @@ static int klp_init_patch(struct klp_patch *patch)
 
 static int __klp_disable_patch(struct klp_patch *patch)
 {
-	struct klp_object *obj;
-
 	if (WARN_ON(!patch->enabled))
 		return -EINVAL;
 
@@ -995,10 +993,6 @@ static int __klp_disable_patch(struct klp_patch *patch)
 
 	klp_states_pre_unpatch(patch);
 
-	klp_for_each_object(patch, obj)
-		if (obj->patched)
-			klp_pre_unpatch_callback(obj);
-
 	/*
 	 * Enforce the order of the func->transition writes in
 	 * klp_init_transition() and the TIF_PATCH_PENDING writes in
@@ -1050,13 +1044,6 @@ static int __klp_enable_patch(struct klp_patch *patch)
 		if (!klp_is_object_loaded(obj))
 			continue;
 
-		ret = klp_pre_patch_callback(obj);
-		if (ret) {
-			pr_warn("pre-patch callback failed for object '%s'\n",
-				klp_is_module(obj) ? obj->name : "vmlinux");
-			goto err;
-		}
-
 		ret = klp_patch_object(obj);
 		if (ret) {
 			pr_warn("failed to patch object '%s'\n",
@@ -1226,14 +1213,10 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
 			if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
 				continue;
 
-			if (patch != klp_transition_patch)
-				klp_pre_unpatch_callback(obj);
-
 			pr_notice("reverting patch '%s' on unloading module '%s'\n",
 				  patch->mod->name, obj->mod->name);
 			klp_unpatch_object(obj);
 
-			klp_post_unpatch_callback(obj);
 			klp_clear_object_relocs(patch, obj);
 			klp_free_object_loaded(obj);
 			break;
@@ -1280,25 +1263,13 @@ int klp_module_coming(struct module *mod)
 			pr_notice("applying patch '%s' to loading module '%s'\n",
 				  patch->mod->name, obj->mod->name);
 
-			ret = klp_pre_patch_callback(obj);
-			if (ret) {
-				pr_warn("pre-patch callback failed for object '%s'\n",
-					obj->name);
-				goto err;
-			}
-
 			ret = klp_patch_object(obj);
 			if (ret) {
 				pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
 					patch->mod->name, obj->mod->name, ret);
-
-				klp_post_unpatch_callback(obj);
 				goto err;
 			}
 
-			if (patch != klp_transition_patch)
-				klp_post_patch_callback(obj);
-
 			break;
 		}
 	}
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index 38209c7361b6..02b8364f6779 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -23,37 +23,4 @@ static inline bool klp_is_object_loaded(struct klp_object *obj)
 	return !obj->name || obj->mod;
 }
 
-static inline int klp_pre_patch_callback(struct klp_object *obj)
-{
-	int ret = 0;
-
-	if (obj->callbacks.pre_patch)
-		ret = (*obj->callbacks.pre_patch)(obj);
-
-	obj->callbacks.post_unpatch_enabled = !ret;
-
-	return ret;
-}
-
-static inline void klp_post_patch_callback(struct klp_object *obj)
-{
-	if (obj->callbacks.post_patch)
-		(*obj->callbacks.post_patch)(obj);
-}
-
-static inline void klp_pre_unpatch_callback(struct klp_object *obj)
-{
-	if (obj->callbacks.pre_unpatch)
-		(*obj->callbacks.pre_unpatch)(obj);
-}
-
-static inline void klp_post_unpatch_callback(struct klp_object *obj)
-{
-	if (obj->callbacks.post_unpatch_enabled &&
-	    obj->callbacks.post_unpatch)
-		(*obj->callbacks.post_unpatch)(obj);
-
-	obj->callbacks.post_unpatch_enabled = false;
-}
-
 #endif /* _LIVEPATCH_CORE_H */
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index f3dce9fe9897..c5e9dcf3e453 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -155,15 +155,6 @@ static void klp_complete_transition(void)
 		klp_states_post_unpatch(klp_transition_patch);
 	}
 
-	klp_for_each_object(klp_transition_patch, obj) {
-		if (!klp_is_object_loaded(obj))
-			continue;
-		if (klp_target_state == KLP_TRANSITION_PATCHED)
-			klp_post_patch_callback(obj);
-		else if (klp_target_state == KLP_TRANSITION_UNPATCHED)
-			klp_post_unpatch_callback(obj);
-	}
-
 	pr_notice("'%s': %s complete\n", klp_transition_patch->mod->name,
 		  klp_target_state == KLP_TRANSITION_PATCHED ? "patching" : "unpatching");
 
-- 
2.47.1