Merge branch 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching

Pull livepatching updates from Jiri Kosina:

 - shadow variables support, allowing livepatches to associate new
   "shadow" fields to existing data structures, from Joe Lawrence

 - pre/post patch callbacks API, allowing livepatch writers to register
   callbacks to be called before and after patch application, from Joe
   Lawrence

* 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: __klp_disable_patch() should never be called for disabled patches
  livepatch: Correctly call klp_post_unpatch_callback() in error paths
  livepatch: add transition notices
  livepatch: move transition "complete" notice into klp_complete_transition()
  livepatch: add (un)patch callbacks
  livepatch: Small shadow variable documentation fixes
  livepatch: __klp_shadow_get_or_alloc() is local to shadow.c
  livepatch: introduce shadow variable API

1 files changed, 38 insertions, 7 deletions

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index b004a1fb6032..56add6327736 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -82,6 +82,10 @@ static void klp_complete_transition(void)
 	unsigned int cpu;
 	bool immediate_func = false;
 
+	pr_debug("'%s': completing %s transition\n",
+		 klp_transition_patch->mod->name,
+		 klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
+
 	if (klp_target_state == KLP_UNPATCHED) {
 		/*
 		 * All tasks have transitioned to KLP_UNPATCHED so we can now
@@ -109,9 +113,6 @@ static void klp_complete_transition(void)
 		}
 	}
 
-	if (klp_target_state == KLP_UNPATCHED && !immediate_func)
-		module_put(klp_transition_patch->mod);
-
 	/* Prevent klp_ftrace_handler() from seeing KLP_UNDEFINED state */
 	if (klp_target_state == KLP_PATCHED)
 		klp_synchronize_transition();
@@ -130,6 +131,27 @@ static void klp_complete_transition(void)
 	}
 
 done:
+	klp_for_each_object(klp_transition_patch, obj) {
+		if (!klp_is_object_loaded(obj))
+			continue;
+		if (klp_target_state == KLP_PATCHED)
+			klp_post_patch_callback(obj);
+		else if (klp_target_state == KLP_UNPATCHED)
+			klp_post_unpatch_callback(obj);
+	}
+
+	pr_notice("'%s': %s complete\n", klp_transition_patch->mod->name,
+		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
+
+	/*
+	 * See complementary comment in __klp_enable_patch() for why we
+	 * keep the module reference for immediate patches.
+	 */
+	if (!klp_transition_patch->immediate && !immediate_func &&
+	    klp_target_state == KLP_UNPATCHED) {
+		module_put(klp_transition_patch->mod);
+	}
+
 	klp_target_state = KLP_UNDEFINED;
 	klp_transition_patch = NULL;
 }
@@ -145,6 +167,9 @@ void klp_cancel_transition(void)
 	if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED))
 		return;
 
+	pr_debug("'%s': canceling patching transition, going to unpatch\n",
+		 klp_transition_patch->mod->name);
+
 	klp_target_state = KLP_UNPATCHED;
 	klp_complete_transition();
 }
@@ -408,9 +433,6 @@ void klp_try_complete_transition(void)
 	}
 
 success:
-	pr_notice("'%s': %s complete\n", klp_transition_patch->mod->name,
-		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
-
 	/* we're done, now cleanup the data structures */
 	klp_complete_transition();
 }
@@ -426,7 +448,8 @@ void klp_start_transition(void)
 
 	WARN_ON_ONCE(klp_target_state == KLP_UNDEFINED);
 
-	pr_notice("'%s': %s...\n", klp_transition_patch->mod->name,
+	pr_notice("'%s': starting %s transition\n",
+		  klp_transition_patch->mod->name,
 		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
 
 	/*
@@ -482,6 +505,9 @@ void klp_init_transition(struct klp_patch *patch, int state)
 	 */
 	klp_target_state = state;
 
+	pr_debug("'%s': initializing %s transition\n", patch->mod->name,
+		 klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
+
 	/*
 	 * If the patch can be applied or reverted immediately, skip the
 	 * per-task transitions.
@@ -547,6 +573,11 @@ void klp_reverse_transition(void)
 	unsigned int cpu;
 	struct task_struct *g, *task;
 
+	pr_debug("'%s': reversing transition from %s\n",
+		 klp_transition_patch->mod->name,
+		 klp_target_state == KLP_PATCHED ? "patching to unpatching" :
+						   "unpatching to patching");
+
 	klp_transition_patch->enabled = !klp_transition_patch->enabled;
 
 	klp_target_state = !klp_target_state;