Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fixes from Thomas Gleixner:
 "Two small fixes for kprobes and perf:

   - Prevent a deadlock in kprobe_optimizer() causes by reverse lock
     ordering

   - Fix a comment typo"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kprobes: Fix potential deadlock in kprobe_optimizer()
  perf/x86: Fix typo in comment

arch/x86/events/core.c

@@ -1236,7 +1236,7 @@ void x86_pmu_enable_event(struct perf_event *event)
  * Add a single event to the PMU.
  *
  * The event is added to the group of enabled events
- * but only if it can be scehduled with existing events.
+ * but only if it can be scheduled with existing events.
  */
 static int x86_pmu_add(struct perf_event *event, int flags)
 {

kernel/kprobes.c

@@ -470,6 +470,7 @@ static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
  */
 static void do_optimize_kprobes(void)
 {
+	lockdep_assert_held(&text_mutex);
 	/*
 	 * The optimization/unoptimization refers online_cpus via
 	 * stop_machine() and cpu-hotplug modifies online_cpus.
@@ -487,9 +488,7 @@ static void do_optimize_kprobes(void)
 	    list_empty(&optimizing_list))
 		return;
 
-	mutex_lock(&text_mutex);
 	arch_optimize_kprobes(&optimizing_list);
-	mutex_unlock(&text_mutex);
 }
 
 /*
@@ -500,6 +499,7 @@ static void do_unoptimize_kprobes(void)
 {
 	struct optimized_kprobe *op, *tmp;
 
+	lockdep_assert_held(&text_mutex);
 	/* See comment in do_optimize_kprobes() */
 	lockdep_assert_cpus_held();
 
@@ -507,7 +507,6 @@ static void do_unoptimize_kprobes(void)
 	if (list_empty(&unoptimizing_list))
 		return;
 
-	mutex_lock(&text_mutex);
 	arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
 	/* Loop free_list for disarming */
 	list_for_each_entry_safe(op, tmp, &freeing_list, list) {
@@ -524,7 +523,6 @@ static void do_unoptimize_kprobes(void)
 		} else
 			list_del_init(&op->list);
 	}
-	mutex_unlock(&text_mutex);
 }
 
 /* Reclaim all kprobes on the free_list */
@@ -556,6 +554,7 @@ static void kprobe_optimizer(struct work_struct *work)
 {
 	mutex_lock(&kprobe_mutex);
 	cpus_read_lock();
+	mutex_lock(&text_mutex);
 	/* Lock modules while optimizing kprobes */
 	mutex_lock(&module_mutex);
 
@@ -583,6 +582,7 @@ static void kprobe_optimizer(struct work_struct *work)
 	do_free_cleaned_kprobes();
 
 	mutex_unlock(&module_mutex);
+	mutex_unlock(&text_mutex);
 	cpus_read_unlock();
 	mutex_unlock(&kprobe_mutex);