Merge branch 'for-5.1/atomic-replace' into for-linus

The atomic replace allows to create cumulative patches. They are useful when
you maintain many livepatches and want to remove one that is lower on the
stack. In addition it is very useful when more patches touch the same function
and there are dependencies between them.

It's also a feature some of the distros are using already to distribute
their patches.

3 files changed, 18 insertions, 26 deletions

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index fe1993399823..eb0ee10a1981 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -522,7 +522,7 @@ static int klp_add_nops(struct klp_patch *patch)
 	struct klp_patch *old_patch;
 	struct klp_object *old_obj;
 
-	list_for_each_entry(old_patch, &klp_patches, list) {
+	klp_for_each_patch(old_patch) {
 		klp_for_each_object(old_patch, old_obj) {
 			int err;
 
@@ -1004,7 +1004,7 @@ int klp_enable_patch(struct klp_patch *patch)
 
 	if (!klp_have_reliable_stack()) {
 		pr_err("This architecture doesn't have support for the livepatch consistency model.\n");
-		return -ENOSYS;
+		return -EOPNOTSUPP;
 	}
 
 
@@ -1057,7 +1057,7 @@ void klp_discard_replaced_patches(struct klp_patch *new_patch)
 {
 	struct klp_patch *old_patch, *tmp_patch;
 
-	list_for_each_entry_safe(old_patch, tmp_patch, &klp_patches, list) {
+	klp_for_each_patch_safe(old_patch, tmp_patch) {
 		if (old_patch == new_patch)
 			return;
 
@@ -1101,7 +1101,7 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
 	struct klp_patch *patch;
 	struct klp_object *obj;
 
-	list_for_each_entry(patch, &klp_patches, list) {
+	klp_for_each_patch(patch) {
 		if (patch == limit)
 			break;
 
@@ -1109,21 +1109,14 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
 			if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
 				continue;
 
-			/*
-			 * Only unpatch the module if the patch is enabled or
-			 * is in transition.
-			 */
-			if (patch->enabled || patch == klp_transition_patch) {
-
-				if (patch != klp_transition_patch)
-					klp_pre_unpatch_callback(obj);
+			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);
+			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_post_unpatch_callback(obj);
 
 			klp_free_object_loaded(obj);
 			break;
@@ -1148,7 +1141,7 @@ int klp_module_coming(struct module *mod)
 	 */
 	mod->klp_alive = true;
 
-	list_for_each_entry(patch, &klp_patches, list) {
+	klp_for_each_patch(patch) {
 		klp_for_each_object(patch, obj) {
 			if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
 				continue;
@@ -1162,13 +1155,6 @@ int klp_module_coming(struct module *mod)
 				goto err;
 			}
 
-			/*
-			 * Only patch the module if the patch is enabled or is
-			 * in transition.
-			 */
-			if (!patch->enabled && patch != klp_transition_patch)
-				break;
-
 			pr_notice("applying patch '%s' to loading module '%s'\n",
 				  patch->mod->name, obj->mod->name);
 
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index e6200f38701f..ec43a40b853f 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -7,6 +7,12 @@
 extern struct mutex klp_mutex;
 extern struct list_head klp_patches;
 
+#define klp_for_each_patch_safe(patch, tmp_patch)		\
+	list_for_each_entry_safe(patch, tmp_patch, &klp_patches, list)
+
+#define klp_for_each_patch(patch)	\
+	list_for_each_entry(patch, &klp_patches, list)
+
 void klp_free_patch_start(struct klp_patch *patch);
 void klp_discard_replaced_patches(struct klp_patch *new_patch);
 void klp_discard_nops(struct klp_patch *new_patch);
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 183b2086ba03..9c89ae8b337a 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -652,6 +652,6 @@ void klp_force_transition(void)
 	for_each_possible_cpu(cpu)
 		klp_update_patch_state(idle_task(cpu));
 
-	list_for_each_entry(patch, &klp_patches, list)
+	klp_for_each_patch(patch)
 		patch->forced = true;
 }