~hc/RK356X_SDK_RELEASE.git

..	..	@@ -1,26 +1,13 @@
	1	+// SPDX-License-Identifier: GPL-2.0+
1	2	/*
2	3	* Read-Copy Update mechanism for mutual exclusion
3		- *
4		- * This program is free software; you can redistribute it and/or modify
5		- * it under the terms of the GNU General Public License as published by
6		- * the Free Software Foundation; either version 2 of the License, or
7		- * (at your option) any later version.
8		- *
9		- * This program is distributed in the hope that it will be useful,
10		- * but WITHOUT ANY WARRANTY; without even the implied warranty of
11		- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12		- * GNU General Public License for more details.
13		- *
14		- * You should have received a copy of the GNU General Public License
15		- * along with this program; if not, you can access it online at
16		- * http://www.gnu.org/licenses/gpl-2.0.html.
17	4	*
18	5	* Copyright IBM Corporation, 2001
19	6	*
20	7	* Authors: Dipankar Sarma <dipankar@in.ibm.com>
21	8	* Manfred Spraul <manfred@colorfullife.com>
22	9	*
23		- * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
	10	+ * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
24	11	* and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
25	12	* Papers:
26	13	* http://www.rdrop.com/users/paulmck/paper/rclockpdcsproof.pdf
..	..	@@ -53,6 +40,9 @@
53	40	#include <linux/rcupdate_wait.h>
54	41	#include <linux/sched/isolation.h>
55	42	#include <linux/kprobes.h>
	43	+#include <linux/slab.h>
	44	+#include <linux/irq_work.h>
	45	+#include <linux/rcupdate_trace.h>
56	46
57	47	#define CREATE_TRACE_POINTS
58	48
..	..	@@ -64,9 +54,7 @@
64	54	#define MODULE_PARAM_PREFIX "rcupdate."
65	55
66	56	#ifndef CONFIG_TINY_RCU
67		-extern int rcu_expedited; /* from sysctl */
68	57	module_param(rcu_expedited, int, 0);
69		-extern int rcu_normal; /* from sysctl */
70	58	module_param(rcu_normal, int, 0);
71	59	static int rcu_normal_after_boot;
72	60	module_param(rcu_normal_after_boot, int, 0);
..	..	@@ -74,9 +62,15 @@
74	62
75	63	#ifdef CONFIG_DEBUG_LOCK_ALLOC
76	64	/**
77		- * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
	65	+ * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section?
	66	+ * @ret: Best guess answer if lockdep cannot be relied on
78	67	*
79		- * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
	68	+ * Returns true if lockdep must be ignored, in which case ``*ret`` contains
	69	+ * the best guess described below. Otherwise returns false, in which
	70	+ * case ``*ret`` tells the caller nothing and the caller should instead
	71	+ * consult lockdep.
	72	+ *
	73	+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an
80	74	* RCU-sched read-side critical section. In absence of
81	75	* CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
82	76	* critical section unless it can prove otherwise. Note that disabling
..	..	@@ -88,35 +82,45 @@
88	82	* Check debug_lockdep_rcu_enabled() to prevent false positives during boot
89	83	* and while lockdep is disabled.
90	84	*
91		- * Note that if the CPU is in the idle loop from an RCU point of
92		- * view (ie: that we are in the section between rcu_idle_enter() and
93		- * rcu_idle_exit()) then rcu_read_lock_held() returns false even if the CPU
94		- * did an rcu_read_lock(). The reason for this is that RCU ignores CPUs
95		- * that are in such a section, considering these as in extended quiescent
96		- * state, so such a CPU is effectively never in an RCU read-side critical
97		- * section regardless of what RCU primitives it invokes. This state of
98		- * affairs is required --- we need to keep an RCU-free window in idle
99		- * where the CPU may possibly enter into low power mode. This way we can
100		- * notice an extended quiescent state to other CPUs that started a grace
101		- * period. Otherwise we would delay any grace period as long as we run in
102		- * the idle task.
	85	+ * Note that if the CPU is in the idle loop from an RCU point of view (ie:
	86	+ * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
	87	+ * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an
	88	+ * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are
	89	+ * in such a section, considering these as in extended quiescent state,
	90	+ * so such a CPU is effectively never in an RCU read-side critical section
	91	+ * regardless of what RCU primitives it invokes. This state of affairs is
	92	+ * required --- we need to keep an RCU-free window in idle where the CPU may
	93	+ * possibly enter into low power mode. This way we can notice an extended
	94	+ * quiescent state to other CPUs that started a grace period. Otherwise
	95	+ * we would delay any grace period as long as we run in the idle task.
103	96	*
104		- * Similarly, we avoid claiming an SRCU read lock held if the current
	97	+ * Similarly, we avoid claiming an RCU read lock held if the current
105	98	* CPU is offline.
106	99	*/
	100	+static bool rcu_read_lock_held_common(bool *ret)
	101	+{
	102	+ if (!debug_lockdep_rcu_enabled()) {
	103	+ *ret = true;
	104	+ return true;
	105	+ }
	106	+ if (!rcu_is_watching()) {
	107	+ *ret = false;
	108	+ return true;
	109	+ }
	110	+ if (!rcu_lockdep_current_cpu_online()) {
	111	+ *ret = false;
	112	+ return true;
	113	+ }
	114	+ return false;
	115	+}
	116	+
107	117	int rcu_read_lock_sched_held(void)
108	118	{
109		- int lockdep_opinion = 0;
	119	+ bool ret;
110	120
111		- if (!debug_lockdep_rcu_enabled())
112		- return 1;
113		- if (!rcu_is_watching())
114		- return 0;
115		- if (!rcu_lockdep_current_cpu_online())
116		- return 0;
117		- if (debug_locks)
118		- lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
119		- return lockdep_opinion \|\| !preemptible();
	121	+ if (rcu_read_lock_held_common(&ret))
	122	+ return ret;
	123	+ return lock_is_held(&rcu_sched_lock_map) \|\| !preemptible();
120	124	}
121	125	EXPORT_SYMBOL(rcu_read_lock_sched_held);
122	126	#endif
..	..	@@ -149,8 +153,7 @@
149	153	*/
150	154	bool rcu_gp_is_expedited(void)
151	155	{
152		- return rcu_expedited \|\| atomic_read(&rcu_expedited_nesting) \|\|
153		- rcu_scheduler_active == RCU_SCHEDULER_INIT;
	156	+ return rcu_expedited \|\| atomic_read(&rcu_expedited_nesting);
154	157	}
155	158	EXPORT_SYMBOL_GPL(rcu_gp_is_expedited);
156	159
..	..	@@ -182,6 +185,8 @@
182	185	}
183	186	EXPORT_SYMBOL_GPL(rcu_unexpedite_gp);
184	187
	188	+static bool rcu_boot_ended __read_mostly;
	189	+
185	190	/*
186	191	* Inform RCU of the end of the in-kernel boot sequence.
187	192	*/
..	..	@@ -190,7 +195,17 @@
190	195	rcu_unexpedite_gp();
191	196	if (rcu_normal_after_boot)
192	197	WRITE_ONCE(rcu_normal, 1);
	198	+ rcu_boot_ended = true;
193	199	}
	200	+
	201	+/*
	202	+ * Let rcutorture know when it is OK to turn it up to eleven.
	203	+ */
	204	+bool rcu_inkernel_boot_has_ended(void)
	205	+{
	206	+ return rcu_boot_ended;
	207	+}
	208	+EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended);
194	209
195	210	#endif /* #ifndef CONFIG_TINY_RCU */
196	211
..	..	@@ -204,11 +219,7 @@
204	219	if (!IS_ENABLED(CONFIG_PROVE_RCU))
205	220	return;
206	221	synchronize_rcu();
207		- synchronize_rcu_bh();
208		- synchronize_sched();
209	222	synchronize_rcu_expedited();
210		- synchronize_rcu_bh_expedited();
211		- synchronize_sched_expedited();
212	223	}
213	224
214	225	#if !defined(CONFIG_TINY_RCU) \|\| defined(CONFIG_SRCU)
..	..	@@ -220,6 +231,7 @@
220	231	{
221	232	rcu_test_sync_prims();
222	233	rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
	234	+ kfree_rcu_scheduler_running();
223	235	rcu_test_sync_prims();
224	236	return 0;
225	237	}
..	..	@@ -229,32 +241,44 @@
229	241
230	242	#ifdef CONFIG_DEBUG_LOCK_ALLOC
231	243	static struct lock_class_key rcu_lock_key;
232		-struct lockdep_map rcu_lock_map =
233		- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
	244	+struct lockdep_map rcu_lock_map = {
	245	+ .name = "rcu_read_lock",
	246	+ .key = &rcu_lock_key,
	247	+ .wait_type_outer = LD_WAIT_FREE,
	248	+ .wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */
	249	+};
234	250	EXPORT_SYMBOL_GPL(rcu_lock_map);
235	251
236	252	static struct lock_class_key rcu_bh_lock_key;
237		-struct lockdep_map rcu_bh_lock_map =
238		- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
	253	+struct lockdep_map rcu_bh_lock_map = {
	254	+ .name = "rcu_read_lock_bh",
	255	+ .key = &rcu_bh_lock_key,
	256	+ .wait_type_outer = LD_WAIT_FREE,
	257	+ .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */
	258	+};
239	259	EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
240	260
241	261	static struct lock_class_key rcu_sched_lock_key;
242		-struct lockdep_map rcu_sched_lock_map =
243		- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
	262	+struct lockdep_map rcu_sched_lock_map = {
	263	+ .name = "rcu_read_lock_sched",
	264	+ .key = &rcu_sched_lock_key,
	265	+ .wait_type_outer = LD_WAIT_FREE,
	266	+ .wait_type_inner = LD_WAIT_SPIN,
	267	+};
244	268	EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
245	269
	270	+// Tell lockdep when RCU callbacks are being invoked.
246	271	static struct lock_class_key rcu_callback_key;
247	272	struct lockdep_map rcu_callback_map =
248	273	STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key);
249	274	EXPORT_SYMBOL_GPL(rcu_callback_map);
250	275
251		-int notrace debug_lockdep_rcu_enabled(void)
	276	+noinstr int notrace debug_lockdep_rcu_enabled(void)
252	277	{
253		- return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks &&
	278	+ return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) &&
254	279	current->lockdep_recursion == 0;
255	280	}
256	281	EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
257		-NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
258	282
259	283	/**
260	284	* rcu_read_lock_held() - might we be in RCU read-side critical section?
..	..	@@ -278,12 +302,10 @@
278	302	*/
279	303	int rcu_read_lock_held(void)
280	304	{
281		- if (!debug_lockdep_rcu_enabled())
282		- return 1;
283		- if (!rcu_is_watching())
284		- return 0;
285		- if (!rcu_lockdep_current_cpu_online())
286		- return 0;
	305	+ bool ret;
	306	+
	307	+ if (rcu_read_lock_held_common(&ret))
	308	+ return ret;
287	309	return lock_is_held(&rcu_lock_map);
288	310	}
289	311	EXPORT_SYMBOL_GPL(rcu_read_lock_held);
..	..	@@ -300,20 +322,32 @@
300	322	*
301	323	* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
302	324	*
303		- * Note that rcu_read_lock() is disallowed if the CPU is either idle or
	325	+ * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or
304	326	* offline from an RCU perspective, so check for those as well.
305	327	*/
306	328	int rcu_read_lock_bh_held(void)
307	329	{
308		- if (!debug_lockdep_rcu_enabled())
309		- return 1;
310		- if (!rcu_is_watching())
311		- return 0;
312		- if (!rcu_lockdep_current_cpu_online())
313		- return 0;
	330	+ bool ret;
	331	+
	332	+ if (rcu_read_lock_held_common(&ret))
	333	+ return ret;
314	334	return in_softirq() \|\| irqs_disabled();
315	335	}
316	336	EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
	337	+
	338	+int rcu_read_lock_any_held(void)
	339	+{
	340	+ bool ret;
	341	+
	342	+ if (rcu_read_lock_held_common(&ret))
	343	+ return ret;
	344	+ if (lock_is_held(&rcu_lock_map) \|\|
	345	+ lock_is_held(&rcu_bh_lock_map) \|\|
	346	+ lock_is_held(&rcu_sched_lock_map))
	347	+ return 1;
	348	+ return !preemptible();
	349	+}
	350	+EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
317	351
318	352	#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
319	353
..	..	@@ -338,35 +372,35 @@
338	372	int i;
339	373	int j;
340	374
341		- /* Initialize and register callbacks for each flavor specified. */
	375	+ /* Initialize and register callbacks for each crcu_array element. */
342	376	for (i = 0; i < n; i++) {
343	377	if (checktiny &&
344		- (crcu_array[i] == call_rcu \|\|
345		- crcu_array[i] == call_rcu_bh)) {
	378	+ (crcu_array[i] == call_rcu)) {
346	379	might_sleep();
347	380	continue;
348	381	}
349		- init_rcu_head_on_stack(&rs_array[i].head);
350		- init_completion(&rs_array[i].completion);
351	382	for (j = 0; j < i; j++)
352	383	if (crcu_array[j] == crcu_array[i])
353	384	break;
354		- if (j == i)
	385	+ if (j == i) {
	386	+ init_rcu_head_on_stack(&rs_array[i].head);
	387	+ init_completion(&rs_array[i].completion);
355	388	(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
	389	+ }
356	390	}
357	391
358	392	/* Wait for all callbacks to be invoked. */
359	393	for (i = 0; i < n; i++) {
360	394	if (checktiny &&
361		- (crcu_array[i] == call_rcu \|\|
362		- crcu_array[i] == call_rcu_bh))
	395	+ (crcu_array[i] == call_rcu))
363	396	continue;
364	397	for (j = 0; j < i; j++)
365	398	if (crcu_array[j] == crcu_array[i])
366	399	break;
367		- if (j == i)
	400	+ if (j == i) {
368	401	wait_for_completion(&rs_array[i].completion);
369		- destroy_rcu_head_on_stack(&rs_array[i].head);
	402	+ destroy_rcu_head_on_stack(&rs_array[i].head);
	403	+ }
370	404	}
371	405	}
372	406	EXPORT_SYMBOL_GPL(__wait_rcu_gp);
..	..	@@ -422,14 +456,14 @@
422	456	}
423	457	EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
424	458
425		-struct debug_obj_descr rcuhead_debug_descr = {
	459	+const struct debug_obj_descr rcuhead_debug_descr = {
426	460	.name = "rcu_head",
427	461	.is_static_object = rcuhead_is_static_object,
428	462	};
429	463	EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
430	464	#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
431	465
432		-#if defined(CONFIG_TREE_RCU) \|\| defined(CONFIG_PREEMPT_RCU) \|\| defined(CONFIG_RCU_TRACE)
	466	+#if defined(CONFIG_TREE_RCU) \|\| defined(CONFIG_RCU_TRACE)
433	467	void do_trace_rcu_torture_read(const char rcutorturename, struct rcu_head rhp,
434	468	unsigned long secs,
435	469	unsigned long c_old, unsigned long c)
..	..	@@ -442,445 +476,42 @@
442	476	do { } while (0)
443	477	#endif
444	478
445		-#ifdef CONFIG_RCU_STALL_COMMON
	479	+#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) \|\| IS_MODULE(CONFIG_RCU_TORTURE_TEST)
	480	+/* Get rcutorture access to sched_setaffinity(). */
	481	+long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
	482	+{
	483	+ int ret;
446	484
447		-#ifdef CONFIG_PROVE_RCU
448		-#define RCU_STALL_DELAY_DELTA (5 * HZ)
449		-#else
450		-#define RCU_STALL_DELAY_DELTA 0
	485	+ ret = sched_setaffinity(pid, in_mask);
	486	+ WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret);
	487	+ return ret;
	488	+}
	489	+EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity);
451	490	#endif
452	491
453		-int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
	492	+#ifdef CONFIG_RCU_STALL_COMMON
	493	+int rcu_cpu_stall_ftrace_dump __read_mostly;
	494	+module_param(rcu_cpu_stall_ftrace_dump, int, 0644);
	495	+int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings.
454	496	EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
455		-static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
456		-
457	497	module_param(rcu_cpu_stall_suppress, int, 0644);
	498	+int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
458	499	module_param(rcu_cpu_stall_timeout, int, 0644);
459		-
460		-int rcu_jiffies_till_stall_check(void)
461		-{
462		- int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout);
463		-
464		- /*
465		- * Limit check must be consistent with the Kconfig limits
466		- * for CONFIG_RCU_CPU_STALL_TIMEOUT.
467		- */
468		- if (till_stall_check < 3) {
469		- WRITE_ONCE(rcu_cpu_stall_timeout, 3);
470		- till_stall_check = 3;
471		- } else if (till_stall_check > 300) {
472		- WRITE_ONCE(rcu_cpu_stall_timeout, 300);
473		- till_stall_check = 300;
474		- }
475		- return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
476		-}
477		-
478		-void rcu_sysrq_start(void)
479		-{
480		- if (!rcu_cpu_stall_suppress)
481		- rcu_cpu_stall_suppress = 2;
482		-}
483		-
484		-void rcu_sysrq_end(void)
485		-{
486		- if (rcu_cpu_stall_suppress == 2)
487		- rcu_cpu_stall_suppress = 0;
488		-}
489		-
490		-static int rcu_panic(struct notifier_block this, unsigned long ev, void ptr)
491		-{
492		- rcu_cpu_stall_suppress = 1;
493		- return NOTIFY_DONE;
494		-}
495		-
496		-static struct notifier_block rcu_panic_block = {
497		- .notifier_call = rcu_panic,
498		-};
499		-
500		-static int __init check_cpu_stall_init(void)
501		-{
502		- atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
503		- return 0;
504		-}
505		-early_initcall(check_cpu_stall_init);
506		-
507	500	#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
508	501
509		-#ifdef CONFIG_TASKS_RCU
510		-
511		-/*
512		- * Simple variant of RCU whose quiescent states are voluntary context
513		- * switch, cond_resched_rcu_qs(), user-space execution, and idle.
514		- * As such, grace periods can take one good long time. There are no
515		- * read-side primitives similar to rcu_read_lock() and rcu_read_unlock()
516		- * because this implementation is intended to get the system into a safe
517		- * state for some of the manipulations involved in tracing and the like.
518		- * Finally, this implementation does not support high call_rcu_tasks()
519		- * rates from multiple CPUs. If this is required, per-CPU callback lists
520		- * will be needed.
521		- */
522		-
523		-/* Global list of callbacks and associated lock. */
524		-static struct rcu_head *rcu_tasks_cbs_head;
525		-static struct rcu_head **rcu_tasks_cbs_tail = &rcu_tasks_cbs_head;
526		-static DECLARE_WAIT_QUEUE_HEAD(rcu_tasks_cbs_wq);
527		-static DEFINE_RAW_SPINLOCK(rcu_tasks_cbs_lock);
528		-
529		-/* Track exiting tasks in order to allow them to be waited for. */
530		-DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu);
531		-
532		-/* Control stall timeouts. Disable with <= 0, otherwise jiffies till stall. */
533		-#define RCU_TASK_STALL_TIMEOUT (HZ * 60 * 10)
534		-static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT;
535		-module_param(rcu_task_stall_timeout, int, 0644);
536		-
537		-static struct task_struct *rcu_tasks_kthread_ptr;
538		-
539		-/**
540		- * call_rcu_tasks() - Queue an RCU for invocation task-based grace period
541		- * @rhp: structure to be used for queueing the RCU updates.
542		- * @func: actual callback function to be invoked after the grace period
543		- *
544		- * The callback function will be invoked some time after a full grace
545		- * period elapses, in other words after all currently executing RCU
546		- * read-side critical sections have completed. call_rcu_tasks() assumes
547		- * that the read-side critical sections end at a voluntary context
548		- * switch (not a preemption!), cond_resched_rcu_qs(), entry into idle,
549		- * or transition to usermode execution. As such, there are no read-side
550		- * primitives analogous to rcu_read_lock() and rcu_read_unlock() because
551		- * this primitive is intended to determine that all tasks have passed
552		- * through a safe state, not so much for data-strcuture synchronization.
553		- *
554		- * See the description of call_rcu() for more detailed information on
555		- * memory ordering guarantees.
556		- */
557		-void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
558		-{
559		- unsigned long flags;
560		- bool needwake;
561		-
562		- rhp->next = NULL;
563		- rhp->func = func;
564		- raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags);
565		- needwake = !rcu_tasks_cbs_head;
566		- *rcu_tasks_cbs_tail = rhp;
567		- rcu_tasks_cbs_tail = &rhp->next;
568		- raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
569		- /* We can't create the thread unless interrupts are enabled. */
570		- if (needwake && READ_ONCE(rcu_tasks_kthread_ptr))
571		- wake_up(&rcu_tasks_cbs_wq);
572		-}
573		-EXPORT_SYMBOL_GPL(call_rcu_tasks);
574		-
575		-/**
576		- * synchronize_rcu_tasks - wait until an rcu-tasks grace period has elapsed.
577		- *
578		- * Control will return to the caller some time after a full rcu-tasks
579		- * grace period has elapsed, in other words after all currently
580		- * executing rcu-tasks read-side critical sections have elapsed. These
581		- * read-side critical sections are delimited by calls to schedule(),
582		- * cond_resched_tasks_rcu_qs(), idle execution, userspace execution, calls
583		- * to synchronize_rcu_tasks(), and (in theory, anyway) cond_resched().
584		- *
585		- * This is a very specialized primitive, intended only for a few uses in
586		- * tracing and other situations requiring manipulation of function
587		- * preambles and profiling hooks. The synchronize_rcu_tasks() function
588		- * is not (yet) intended for heavy use from multiple CPUs.
589		- *
590		- * Note that this guarantee implies further memory-ordering guarantees.
591		- * On systems with more than one CPU, when synchronize_rcu_tasks() returns,
592		- * each CPU is guaranteed to have executed a full memory barrier since the
593		- * end of its last RCU-tasks read-side critical section whose beginning
594		- * preceded the call to synchronize_rcu_tasks(). In addition, each CPU
595		- * having an RCU-tasks read-side critical section that extends beyond
596		- * the return from synchronize_rcu_tasks() is guaranteed to have executed
597		- * a full memory barrier after the beginning of synchronize_rcu_tasks()
598		- * and before the beginning of that RCU-tasks read-side critical section.
599		- * Note that these guarantees include CPUs that are offline, idle, or
600		- * executing in user mode, as well as CPUs that are executing in the kernel.
601		- *
602		- * Furthermore, if CPU A invoked synchronize_rcu_tasks(), which returned
603		- * to its caller on CPU B, then both CPU A and CPU B are guaranteed
604		- * to have executed a full memory barrier during the execution of
605		- * synchronize_rcu_tasks() -- even if CPU A and CPU B are the same CPU
606		- * (but again only if the system has more than one CPU).
607		- */
608		-void synchronize_rcu_tasks(void)
609		-{
610		- /* Complain if the scheduler has not started. */
611		- RCU_LOCKDEP_WARN(rcu_scheduler_active == RCU_SCHEDULER_INACTIVE,
612		- "synchronize_rcu_tasks called too soon");
613		-
614		- /* Wait for the grace period. */
615		- wait_rcu_gp(call_rcu_tasks);
616		-}
617		-EXPORT_SYMBOL_GPL(synchronize_rcu_tasks);
618		-
619		-/**
620		- * rcu_barrier_tasks - Wait for in-flight call_rcu_tasks() callbacks.
621		- *
622		- * Although the current implementation is guaranteed to wait, it is not
623		- * obligated to, for example, if there are no pending callbacks.
624		- */
625		-void rcu_barrier_tasks(void)
626		-{
627		- /* There is only one callback queue, so this is easy. ;-) */
628		- synchronize_rcu_tasks();
629		-}
630		-EXPORT_SYMBOL_GPL(rcu_barrier_tasks);
631		-
632		-/* See if tasks are still holding out, complain if so. */
633		-static void check_holdout_task(struct task_struct *t,
634		- bool needreport, bool *firstreport)
635		-{
636		- int cpu;
637		-
638		- if (!READ_ONCE(t->rcu_tasks_holdout) \|\|
639		- t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) \|\|
640		- !READ_ONCE(t->on_rq) \|\|
641		- (IS_ENABLED(CONFIG_NO_HZ_FULL) &&
642		- !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
643		- WRITE_ONCE(t->rcu_tasks_holdout, false);
644		- list_del_init(&t->rcu_tasks_holdout_list);
645		- put_task_struct(t);
646		- return;
647		- }
648		- rcu_request_urgent_qs_task(t);
649		- if (!needreport)
650		- return;
651		- if (*firstreport) {
652		- pr_err("INFO: rcu_tasks detected stalls on tasks:\n");
653		- *firstreport = false;
654		- }
655		- cpu = task_cpu(t);
656		- pr_alert("%p: %c%c nvcsw: %lu/%lu holdout: %d idle_cpu: %d/%d\n",
657		- t, ".I"[is_idle_task(t)],
658		- "N."[cpu < 0 \|\| !tick_nohz_full_cpu(cpu)],
659		- t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout,
660		- t->rcu_tasks_idle_cpu, cpu);
661		- sched_show_task(t);
662		-}
663		-
664		-/* RCU-tasks kthread that detects grace periods and invokes callbacks. */
665		-static int __noreturn rcu_tasks_kthread(void *arg)
666		-{
667		- unsigned long flags;
668		- struct task_struct g, t;
669		- unsigned long lastreport;
670		- struct rcu_head *list;
671		- struct rcu_head *next;
672		- LIST_HEAD(rcu_tasks_holdouts);
673		- int fract;
674		-
675		- /* Run on housekeeping CPUs by default. Sysadm can move if desired. */
676		- housekeeping_affine(current, HK_FLAG_RCU);
677		-
678		- /*
679		- * Each pass through the following loop makes one check for
680		- * newly arrived callbacks, and, if there are some, waits for
681		- * one RCU-tasks grace period and then invokes the callbacks.
682		- * This loop is terminated by the system going down. ;-)
683		- */
684		- for (;;) {
685		-
686		- /* Pick up any new callbacks. */
687		- raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags);
688		- list = rcu_tasks_cbs_head;
689		- rcu_tasks_cbs_head = NULL;
690		- rcu_tasks_cbs_tail = &rcu_tasks_cbs_head;
691		- raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
692		-
693		- /* If there were none, wait a bit and start over. */
694		- if (!list) {
695		- wait_event_interruptible(rcu_tasks_cbs_wq,
696		- rcu_tasks_cbs_head);
697		- if (!rcu_tasks_cbs_head) {
698		- WARN_ON(signal_pending(current));
699		- schedule_timeout_interruptible(HZ/10);
700		- }
701		- continue;
702		- }
703		-
704		- /*
705		- * Wait for all pre-existing t->on_rq and t->nvcsw
706		- * transitions to complete. Invoking synchronize_sched()
707		- * suffices because all these transitions occur with
708		- * interrupts disabled. Without this synchronize_sched(),
709		- * a read-side critical section that started before the
710		- * grace period might be incorrectly seen as having started
711		- * after the grace period.
712		- *
713		- * This synchronize_sched() also dispenses with the
714		- * need for a memory barrier on the first store to
715		- * ->rcu_tasks_holdout, as it forces the store to happen
716		- * after the beginning of the grace period.
717		- */
718		- synchronize_sched();
719		-
720		- /*
721		- * There were callbacks, so we need to wait for an
722		- * RCU-tasks grace period. Start off by scanning
723		- * the task list for tasks that are not already
724		- * voluntarily blocked. Mark these tasks and make
725		- * a list of them in rcu_tasks_holdouts.
726		- */
727		- rcu_read_lock();
728		- for_each_process_thread(g, t) {
729		- if (t != current && READ_ONCE(t->on_rq) &&
730		- !is_idle_task(t)) {
731		- get_task_struct(t);
732		- t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw);
733		- WRITE_ONCE(t->rcu_tasks_holdout, true);
734		- list_add(&t->rcu_tasks_holdout_list,
735		- &rcu_tasks_holdouts);
736		- }
737		- }
738		- rcu_read_unlock();
739		-
740		- /*
741		- * Wait for tasks that are in the process of exiting.
742		- * This does only part of the job, ensuring that all
743		- * tasks that were previously exiting reach the point
744		- * where they have disabled preemption, allowing the
745		- * later synchronize_sched() to finish the job.
746		- */
747		- synchronize_srcu(&tasks_rcu_exit_srcu);
748		-
749		- /*
750		- * Each pass through the following loop scans the list
751		- * of holdout tasks, removing any that are no longer
752		- * holdouts. When the list is empty, we are done.
753		- */
754		- lastreport = jiffies;
755		-
756		- /* Start off with HZ/10 wait and slowly back off to 1 HZ wait*/
757		- fract = 10;
758		-
759		- for (;;) {
760		- bool firstreport;
761		- bool needreport;
762		- int rtst;
763		- struct task_struct *t1;
764		-
765		- if (list_empty(&rcu_tasks_holdouts))
766		- break;
767		-
768		- /* Slowly back off waiting for holdouts */
769		- schedule_timeout_interruptible(HZ/fract);
770		-
771		- if (fract > 1)
772		- fract--;
773		-
774		- rtst = READ_ONCE(rcu_task_stall_timeout);
775		- needreport = rtst > 0 &&
776		- time_after(jiffies, lastreport + rtst);
777		- if (needreport)
778		- lastreport = jiffies;
779		- firstreport = true;
780		- WARN_ON(signal_pending(current));
781		- list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts,
782		- rcu_tasks_holdout_list) {
783		- check_holdout_task(t, needreport, &firstreport);
784		- cond_resched();
785		- }
786		- }
787		-
788		- /*
789		- * Because ->on_rq and ->nvcsw are not guaranteed
790		- * to have a full memory barriers prior to them in the
791		- * schedule() path, memory reordering on other CPUs could
792		- * cause their RCU-tasks read-side critical sections to
793		- * extend past the end of the grace period. However,
794		- * because these ->nvcsw updates are carried out with
795		- * interrupts disabled, we can use synchronize_sched()
796		- * to force the needed ordering on all such CPUs.
797		- *
798		- * This synchronize_sched() also confines all
799		- * ->rcu_tasks_holdout accesses to be within the grace
800		- * period, avoiding the need for memory barriers for
801		- * ->rcu_tasks_holdout accesses.
802		- *
803		- * In addition, this synchronize_sched() waits for exiting
804		- * tasks to complete their final preempt_disable() region
805		- * of execution, cleaning up after the synchronize_srcu()
806		- * above.
807		- */
808		- synchronize_sched();
809		-
810		- /* Invoke the callbacks. */
811		- while (list) {
812		- next = list->next;
813		- local_bh_disable();
814		- list->func(list);
815		- local_bh_enable();
816		- list = next;
817		- cond_resched();
818		- }
819		- /* Paranoid sleep to keep this from entering a tight loop */
820		- schedule_timeout_uninterruptible(HZ/10);
821		- }
822		-}
823		-
824		-/* Spawn rcu_tasks_kthread() at core_initcall() time. */
825		-static int __init rcu_spawn_tasks_kthread(void)
826		-{
827		- struct task_struct *t;
828		-
829		- t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
830		- BUG_ON(IS_ERR(t));
831		- smp_mb(); /* Ensure others see full kthread. */
832		- WRITE_ONCE(rcu_tasks_kthread_ptr, t);
833		- return 0;
834		-}
835		-core_initcall(rcu_spawn_tasks_kthread);
836		-
837		-/* Do the srcu_read_lock() for the above synchronize_srcu(). */
838		-void exit_tasks_rcu_start(void)
839		-{
840		- preempt_disable();
841		- current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
842		- preempt_enable();
843		-}
844		-
845		-/* Do the srcu_read_unlock() for the above synchronize_srcu(). */
846		-void exit_tasks_rcu_finish(void)
847		-{
848		- preempt_disable();
849		- __srcu_read_unlock(&tasks_rcu_exit_srcu, current->rcu_tasks_idx);
850		- preempt_enable();
851		-}
852		-
853		-#endif /* #ifdef CONFIG_TASKS_RCU */
854		-
855		-#ifndef CONFIG_TINY_RCU
856		-
857		-/*
858		- * Print any non-default Tasks RCU settings.
859		- */
860		-static void __init rcu_tasks_bootup_oddness(void)
861		-{
862		-#ifdef CONFIG_TASKS_RCU
863		- if (rcu_task_stall_timeout != RCU_TASK_STALL_TIMEOUT)
864		- pr_info("\tTasks-RCU CPU stall warnings timeout set to %d (rcu_task_stall_timeout).\n", rcu_task_stall_timeout);
865		- else
866		- pr_info("\tTasks RCU enabled.\n");
867		-#endif /* #ifdef CONFIG_TASKS_RCU */
868		-}
869		-
870		-#endif /* #ifndef CONFIG_TINY_RCU */
	502	+// Suppress boot-time RCU CPU stall warnings and rcutorture writer stall
	503	+// warnings. Also used by rcutorture even if stall warnings are excluded.
	504	+int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls.
	505	+EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot);
	506	+module_param(rcu_cpu_stall_suppress_at_boot, int, 0444);
871	507
872	508	#ifdef CONFIG_PROVE_RCU
873	509
874	510	/*
875		- * Early boot self test parameters, one for each flavor
	511	+ * Early boot self test parameters.
876	512	*/
877	513	static bool rcu_self_test;
878		-static bool rcu_self_test_bh;
879		-static bool rcu_self_test_sched;
880		-
881	514	module_param(rcu_self_test, bool, 0444);
882		-module_param(rcu_self_test_bh, bool, 0444);
883		-module_param(rcu_self_test_sched, bool, 0444);
884	515
885	516	static int rcu_self_test_counter;
886	517
..	..	@@ -890,25 +521,24 @@
890	521	pr_info("RCU test callback executed %d\n", rcu_self_test_counter);
891	522	}
892	523
	524	+DEFINE_STATIC_SRCU(early_srcu);
	525	+
	526	+struct early_boot_kfree_rcu {
	527	+ struct rcu_head rh;
	528	+};
	529	+
893	530	static void early_boot_test_call_rcu(void)
894	531	{
895	532	static struct rcu_head head;
	533	+ static struct rcu_head shead;
	534	+ struct early_boot_kfree_rcu *rhp;
896	535
897	536	call_rcu(&head, test_callback);
898		-}
899		-
900		-static void early_boot_test_call_rcu_bh(void)
901		-{
902		- static struct rcu_head head;
903		-
904		- call_rcu_bh(&head, test_callback);
905		-}
906		-
907		-static void early_boot_test_call_rcu_sched(void)
908		-{
909		- static struct rcu_head head;
910		-
911		- call_rcu_sched(&head, test_callback);
	537	+ if (IS_ENABLED(CONFIG_SRCU))
	538	+ call_srcu(&early_srcu, &shead, test_callback);
	539	+ rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
	540	+ if (!WARN_ON_ONCE(!rhp))
	541	+ kfree_rcu(rhp, rh);
912	542	}
913	543
914	544	void rcu_early_boot_tests(void)
..	..	@@ -917,10 +547,6 @@
917	547
918	548	if (rcu_self_test)
919	549	early_boot_test_call_rcu();
920		- if (rcu_self_test_bh)
921		- early_boot_test_call_rcu_bh();
922		- if (rcu_self_test_sched)
923		- early_boot_test_call_rcu_sched();
924	550	rcu_test_sync_prims();
925	551	}
926	552
..	..	@@ -932,16 +558,11 @@
932	558	if (rcu_self_test) {
933	559	early_boot_test_counter++;
934	560	rcu_barrier();
	561	+ if (IS_ENABLED(CONFIG_SRCU)) {
	562	+ early_boot_test_counter++;
	563	+ srcu_barrier(&early_srcu);
	564	+ }
935	565	}
936		- if (rcu_self_test_bh) {
937		- early_boot_test_counter++;
938		- rcu_barrier_bh();
939		- }
940		- if (rcu_self_test_sched) {
941		- early_boot_test_counter++;
942		- rcu_barrier_sched();
943		- }
944		-
945	566	if (rcu_self_test_counter != early_boot_test_counter) {
946	567	WARN_ON(1);
947	568	ret = -1;
..	..	@@ -954,6 +575,8 @@
954	575	void rcu_early_boot_tests(void) {}
955	576	#endif /* CONFIG_PROVE_RCU */
956	577
	578	+#include "tasks.h"
	579	+
957	580	#ifndef CONFIG_TINY_RCU
958	581
959	582	/*