Merge branches 'doc.2018.08.30a', 'dynticks.2018.08.30b', 'srcu.2018.08.30b' and 'torture.2018.08.29a' into HEAD

doc.2018.08.30a: Documentation updates
dynticks.2018.08.30b: RCU flavor consolidation updates and cleanups
srcu.2018.08.30b: SRCU updates
torture.2018.08.29a: Torture-test updates

kernel/rcu/update.c

@@ -203,11 +203,7 @@ void rcu_test_sync_prims(void)
 	if (!IS_ENABLED(CONFIG_PROVE_RCU))
 		return;
 	synchronize_rcu();
-	synchronize_rcu_bh();
-	synchronize_sched();
 	synchronize_rcu_expedited();
-	synchronize_rcu_bh_expedited();
-	synchronize_sched_expedited();
 }
 
 #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU)
@@ -298,7 +294,7 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_held);
  *
  * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
  *
- * Note that rcu_read_lock() is disallowed if the CPU is either idle or
+ * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or
  * offline from an RCU perspective, so check for those as well.
  */
 int rcu_read_lock_bh_held(void)
@@ -336,7 +332,7 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
 	int i;
 	int j;
 
-	/* Initialize and register callbacks for each flavor specified. */
+	/* Initialize and register callbacks for each crcu_array element. */
 	for (i = 0; i < n; i++) {
 		if (checktiny &&
 		    (crcu_array[i] == call_rcu ||
@@ -472,6 +468,7 @@ int rcu_jiffies_till_stall_check(void)
 	}
 	return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
 }
+EXPORT_SYMBOL_GPL(rcu_jiffies_till_stall_check);
 
 void rcu_sysrq_start(void)
 {
@@ -701,19 +698,19 @@ static int __noreturn rcu_tasks_kthread(void *arg)
 
 		/*
 		 * Wait for all pre-existing t->on_rq and t->nvcsw
-		 * transitions to complete.  Invoking synchronize_sched()
+		 * transitions to complete.  Invoking synchronize_rcu()
 		 * suffices because all these transitions occur with
-		 * interrupts disabled.  Without this synchronize_sched(),
+		 * interrupts disabled.  Without this synchronize_rcu(),
 		 * a read-side critical section that started before the
 		 * grace period might be incorrectly seen as having started
 		 * after the grace period.
 		 *
-		 * This synchronize_sched() also dispenses with the
+		 * This synchronize_rcu() also dispenses with the
 		 * need for a memory barrier on the first store to
 		 * ->rcu_tasks_holdout, as it forces the store to happen
 		 * after the beginning of the grace period.
 		 */
-		synchronize_sched();
+		synchronize_rcu();
 
 		/*
 		 * There were callbacks, so we need to wait for an
@@ -740,7 +737,7 @@ static int __noreturn rcu_tasks_kthread(void *arg)
 		 * This does only part of the job, ensuring that all
 		 * tasks that were previously exiting reach the point
 		 * where they have disabled preemption, allowing the
-		 * later synchronize_sched() to finish the job.
+		 * later synchronize_rcu() to finish the job.
 		 */
 		synchronize_srcu(&tasks_rcu_exit_srcu);
 
@@ -790,20 +787,20 @@ static int __noreturn rcu_tasks_kthread(void *arg)
 		 * cause their RCU-tasks read-side critical sections to
 		 * extend past the end of the grace period.  However,
 		 * because these ->nvcsw updates are carried out with
-		 * interrupts disabled, we can use synchronize_sched()
+		 * interrupts disabled, we can use synchronize_rcu()
 		 * to force the needed ordering on all such CPUs.
 		 *
-		 * This synchronize_sched() also confines all
+		 * This synchronize_rcu() also confines all
 		 * ->rcu_tasks_holdout accesses to be within the grace
 		 * period, avoiding the need for memory barriers for
 		 * ->rcu_tasks_holdout accesses.
 		 *
-		 * In addition, this synchronize_sched() waits for exiting
+		 * In addition, this synchronize_rcu() waits for exiting
 		 * tasks to complete their final preempt_disable() region
 		 * of execution, cleaning up after the synchronize_srcu()
 		 * above.
 		 */
-		synchronize_sched();
+		synchronize_rcu();
 
 		/* Invoke the callbacks. */
 		while (list) {
@@ -870,15 +867,10 @@ static void __init rcu_tasks_bootup_oddness(void)
 #ifdef CONFIG_PROVE_RCU
 
 /*
- * Early boot self test parameters, one for each flavor
+ * Early boot self test parameters.
  */
 static bool rcu_self_test;
-static bool rcu_self_test_bh;
-static bool rcu_self_test_sched;
-
 module_param(rcu_self_test, bool, 0444);
-module_param(rcu_self_test_bh, bool, 0444);
-module_param(rcu_self_test_sched, bool, 0444);
 
 static int rcu_self_test_counter;
 
@@ -888,25 +880,16 @@ static void test_callback(struct rcu_head *r)
 	pr_info("RCU test callback executed %d\n", rcu_self_test_counter);
 }
 
+DEFINE_STATIC_SRCU(early_srcu);
+
 static void early_boot_test_call_rcu(void)
 {
 	static struct rcu_head head;
+	static struct rcu_head shead;
 
 	call_rcu(&head, test_callback);
-}
-
-static void early_boot_test_call_rcu_bh(void)
-{
-	static struct rcu_head head;
-
-	call_rcu_bh(&head, test_callback);
-}
-
-static void early_boot_test_call_rcu_sched(void)
-{
-	static struct rcu_head head;
-
-	call_rcu_sched(&head, test_callback);
+	if (IS_ENABLED(CONFIG_SRCU))
+		call_srcu(&early_srcu, &shead, test_callback);
 }
 
 void rcu_early_boot_tests(void)
@@ -915,10 +898,6 @@ void rcu_early_boot_tests(void)
 
 	if (rcu_self_test)
 		early_boot_test_call_rcu();
-	if (rcu_self_test_bh)
-		early_boot_test_call_rcu_bh();
-	if (rcu_self_test_sched)
-		early_boot_test_call_rcu_sched();
 	rcu_test_sync_prims();
 }
 
@@ -930,16 +909,11 @@ static int rcu_verify_early_boot_tests(void)
 	if (rcu_self_test) {
 		early_boot_test_counter++;
 		rcu_barrier();
+		if (IS_ENABLED(CONFIG_SRCU)) {
+			early_boot_test_counter++;
+			srcu_barrier(&early_srcu);
+		}
 	}
-	if (rcu_self_test_bh) {
-		early_boot_test_counter++;
-		rcu_barrier_bh();
-	}
-	if (rcu_self_test_sched) {
-		early_boot_test_counter++;
-		rcu_barrier_sched();
-	}
-
 	if (rcu_self_test_counter != early_boot_test_counter) {
 		WARN_ON(1);
 		ret = -1;