Merge branch 'perf/core' into perf/uprobes

Merge in latest upstream (and the latest perf development tree),
to prepare for tooling changes, and also to pick up v3.4 MM
changes that the uprobes code needs to take care of.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 60 insertions, 17 deletions

diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index 9cb1ae4aabd..22ecea0dfb6 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -132,6 +132,7 @@ static struct rcu_preempt_ctrlblk rcu_preempt_ctrlblk = {
 	RCU_TRACE(.rcb.name = "rcu_preempt")
 };
 
+static void rcu_read_unlock_special(struct task_struct *t);
 static int rcu_preempted_readers_exp(void);
 static void rcu_report_exp_done(void);
 
@@ -146,6 +147,16 @@ static int rcu_cpu_blocking_cur_gp(void)
 /*
  * Check for a running RCU reader.  Because there is only one CPU,
  * there can be but one running RCU reader at a time.  ;-)
+ *
+ * Returns zero if there are no running readers.  Returns a positive
+ * number if there is at least one reader within its RCU read-side
+ * critical section.  Returns a negative number if an outermost reader
+ * is in the midst of exiting from its RCU read-side critical section
+ *
+ * Returns zero if there are no running readers.  Returns a positive
+ * number if there is at least one reader within its RCU read-side
+ * critical section.  Returns a negative number if an outermost reader
+ * is in the midst of exiting from its RCU read-side critical section.
  */
 static int rcu_preempt_running_reader(void)
 {
@@ -307,7 +318,6 @@ static int rcu_boost(void)
 	t = container_of(tb, struct task_struct, rcu_node_entry);
 	rt_mutex_init_proxy_locked(&mtx, t);
 	t->rcu_boost_mutex = &mtx;
-	t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BOOSTED;
 	raw_local_irq_restore(flags);
 	rt_mutex_lock(&mtx);
 	rt_mutex_unlock(&mtx);  /* Keep lockdep happy. */
@@ -475,7 +485,7 @@ void rcu_preempt_note_context_switch(void)
 	unsigned long flags;
 
 	local_irq_save(flags); /* must exclude scheduler_tick(). */
-	if (rcu_preempt_running_reader() &&
+	if (rcu_preempt_running_reader() > 0 &&
 	    (t->rcu_read_unlock_special & RCU_READ_UNLOCK_BLOCKED) == 0) {
 
 		/* Possibly blocking in an RCU read-side critical section. */
@@ -494,6 +504,13 @@ void rcu_preempt_note_context_switch(void)
 		list_add(&t->rcu_node_entry, &rcu_preempt_ctrlblk.blkd_tasks);
 		if (rcu_cpu_blocking_cur_gp())
 			rcu_preempt_ctrlblk.gp_tasks = &t->rcu_node_entry;
+	} else if (rcu_preempt_running_reader() < 0 &&
+		   t->rcu_read_unlock_special) {
+		/*
+		 * Complete exit from RCU read-side critical section on
+		 * behalf of preempted instance of __rcu_read_unlock().
+		 */
+		rcu_read_unlock_special(t);
 	}
 
 	/*
@@ -526,12 +543,15 @@ EXPORT_SYMBOL_GPL(__rcu_read_lock);
  * notify RCU core processing or task having blocked during the RCU
  * read-side critical section.
  */
-static void rcu_read_unlock_special(struct task_struct *t)
+static noinline void rcu_read_unlock_special(struct task_struct *t)
 {
 	int empty;
 	int empty_exp;
 	unsigned long flags;
 	struct list_head *np;
+#ifdef CONFIG_RCU_BOOST
+	struct rt_mutex *rbmp = NULL;
+#endif /* #ifdef CONFIG_RCU_BOOST */
 	int special;
 
 	/*
@@ -552,7 +572,7 @@ static void rcu_read_unlock_special(struct task_struct *t)
 		rcu_preempt_cpu_qs();
 
 	/* Hardware IRQ handlers cannot block. */
-	if (in_irq()) {
+	if (in_irq() || in_serving_softirq()) {
 		local_irq_restore(flags);
 		return;
 	}
@@ -597,10 +617,10 @@ static void rcu_read_unlock_special(struct task_struct *t)
 	}
 #ifdef CONFIG_RCU_BOOST
 	/* Unboost self if was boosted. */
-	if (special & RCU_READ_UNLOCK_BOOSTED) {
-		t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_BOOSTED;
-		rt_mutex_unlock(t->rcu_boost_mutex);
+	if (t->rcu_boost_mutex != NULL) {
+		rbmp = t->rcu_boost_mutex;
 		t->rcu_boost_mutex = NULL;
+		rt_mutex_unlock(rbmp);
 	}
 #endif /* #ifdef CONFIG_RCU_BOOST */
 	local_irq_restore(flags);
@@ -618,13 +638,22 @@ void __rcu_read_unlock(void)
 	struct task_struct *t = current;
 
 	barrier();  /* needed if we ever invoke rcu_read_unlock in rcutiny.c */
-	--t->rcu_read_lock_nesting;
-	barrier();  /* decrement before load of ->rcu_read_unlock_special */
-	if (t->rcu_read_lock_nesting == 0 &&
-	    unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
-		rcu_read_unlock_special(t);
+	if (t->rcu_read_lock_nesting != 1)
+		--t->rcu_read_lock_nesting;
+	else {
+		t->rcu_read_lock_nesting = INT_MIN;
+		barrier();  /* assign before ->rcu_read_unlock_special load */
+		if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
+			rcu_read_unlock_special(t);
+		barrier();  /* ->rcu_read_unlock_special load before assign */
+		t->rcu_read_lock_nesting = 0;
+	}
 #ifdef CONFIG_PROVE_LOCKING
-	WARN_ON_ONCE(t->rcu_read_lock_nesting < 0);
+	{
+		int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting);
+
+		WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2);
+	}
 #endif /* #ifdef CONFIG_PROVE_LOCKING */
 }
 EXPORT_SYMBOL_GPL(__rcu_read_unlock);
@@ -649,7 +678,7 @@ static void rcu_preempt_check_callbacks(void)
 		invoke_rcu_callbacks();
 	if (rcu_preempt_gp_in_progress() &&
 	    rcu_cpu_blocking_cur_gp() &&
-	    rcu_preempt_running_reader())
+	    rcu_preempt_running_reader() > 0)
 		t->rcu_read_unlock_special |= RCU_READ_UNLOCK_NEED_QS;
 }
 
@@ -706,6 +735,11 @@ EXPORT_SYMBOL_GPL(call_rcu);
  */
 void synchronize_rcu(void)
 {
+	rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map) &&
+			   !lock_is_held(&rcu_lock_map) &&
+			   !lock_is_held(&rcu_sched_lock_map),
+			   "Illegal synchronize_rcu() in RCU read-side critical section");
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	if (!rcu_scheduler_active)
 		return;
@@ -882,7 +916,8 @@ static void rcu_preempt_process_callbacks(void)
 static void invoke_rcu_callbacks(void)
 {
 	have_rcu_kthread_work = 1;
-	wake_up(&rcu_kthread_wq);
+	if (rcu_kthread_task != NULL)
+		wake_up(&rcu_kthread_wq);
 }
 
 #ifdef CONFIG_RCU_TRACE
@@ -943,12 +978,16 @@ early_initcall(rcu_spawn_kthreads);
 
 #else /* #ifdef CONFIG_RCU_BOOST */
 
+/* Hold off callback invocation until early_initcall() time. */
+static int rcu_scheduler_fully_active __read_mostly;
+
 /*
  * Start up softirq processing of callbacks.
  */
 void invoke_rcu_callbacks(void)
 {
-	raise_softirq(RCU_SOFTIRQ);
+	if (rcu_scheduler_fully_active)
+		raise_softirq(RCU_SOFTIRQ);
 }
 
 #ifdef CONFIG_RCU_TRACE
@@ -963,10 +1002,14 @@ static bool rcu_is_callbacks_kthread(void)
 
 #endif /* #ifdef CONFIG_RCU_TRACE */
 
-void rcu_init(void)
+static int __init rcu_scheduler_really_started(void)
 {
+	rcu_scheduler_fully_active = 1;
 	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+	raise_softirq(RCU_SOFTIRQ);  /* Invoke any callbacks from early boot. */
+	return 0;
 }
+early_initcall(rcu_scheduler_really_started);
 
 #endif /* #else #ifdef CONFIG_RCU_BOOST */