~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
..	..	@@ -64,21 +54,25 @@
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		-static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT_FULL);
72		-#ifndef CONFIG_PREEMPT_RT_FULL
	59	+static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT);
	60	+#ifndef CONFIG_PREEMPT_RT
73	61	module_param(rcu_normal_after_boot, int, 0);
74	62	#endif
75	63	#endif /* #ifndef CONFIG_TINY_RCU */
76	64
77	65	#ifdef CONFIG_DEBUG_LOCK_ALLOC
78	66	/**
79		- * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
	67	+ * rcu_read_lock_held_common() - might we be in RCU-sched read-side critical section?
	68	+ * @ret: Best guess answer if lockdep cannot be relied on
80	69	*
81		- * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
	70	+ * Returns true if lockdep must be ignored, in which case ``*ret`` contains
	71	+ * the best guess described below. Otherwise returns false, in which
	72	+ * case ``*ret`` tells the caller nothing and the caller should instead
	73	+ * consult lockdep.
	74	+ *
	75	+ * If CONFIG_DEBUG_LOCK_ALLOC is selected, set ``*ret`` to nonzero iff in an
82	76	* RCU-sched read-side critical section. In absence of
83	77	* CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
84	78	* critical section unless it can prove otherwise. Note that disabling
..	..	@@ -90,35 +84,45 @@
90	84	* Check debug_lockdep_rcu_enabled() to prevent false positives during boot
91	85	* and while lockdep is disabled.
92	86	*
93		- * Note that if the CPU is in the idle loop from an RCU point of
94		- * view (ie: that we are in the section between rcu_idle_enter() and
95		- * rcu_idle_exit()) then rcu_read_lock_held() returns false even if the CPU
96		- * did an rcu_read_lock(). The reason for this is that RCU ignores CPUs
97		- * that are in such a section, considering these as in extended quiescent
98		- * state, so such a CPU is effectively never in an RCU read-side critical
99		- * section regardless of what RCU primitives it invokes. This state of
100		- * affairs is required --- we need to keep an RCU-free window in idle
101		- * where the CPU may possibly enter into low power mode. This way we can
102		- * notice an extended quiescent state to other CPUs that started a grace
103		- * period. Otherwise we would delay any grace period as long as we run in
104		- * the idle task.
	87	+ * Note that if the CPU is in the idle loop from an RCU point of view (ie:
	88	+ * that we are in the section between rcu_idle_enter() and rcu_idle_exit())
	89	+ * then rcu_read_lock_held() sets ``*ret`` to false even if the CPU did an
	90	+ * rcu_read_lock(). The reason for this is that RCU ignores CPUs that are
	91	+ * in such a section, considering these as in extended quiescent state,
	92	+ * so such a CPU is effectively never in an RCU read-side critical section
	93	+ * regardless of what RCU primitives it invokes. This state of affairs is
	94	+ * required --- we need to keep an RCU-free window in idle where the CPU may
	95	+ * possibly enter into low power mode. This way we can notice an extended
	96	+ * quiescent state to other CPUs that started a grace period. Otherwise
	97	+ * we would delay any grace period as long as we run in the idle task.
105	98	*
106		- * Similarly, we avoid claiming an SRCU read lock held if the current
	99	+ * Similarly, we avoid claiming an RCU read lock held if the current
107	100	* CPU is offline.
108	101	*/
	102	+static bool rcu_read_lock_held_common(bool *ret)
	103	+{
	104	+ if (!debug_lockdep_rcu_enabled()) {
	105	+ *ret = true;
	106	+ return true;
	107	+ }
	108	+ if (!rcu_is_watching()) {
	109	+ *ret = false;
	110	+ return true;
	111	+ }
	112	+ if (!rcu_lockdep_current_cpu_online()) {
	113	+ *ret = false;
	114	+ return true;
	115	+ }
	116	+ return false;
	117	+}
	118	+
109	119	int rcu_read_lock_sched_held(void)
110	120	{
111		- int lockdep_opinion = 0;
	121	+ bool ret;
112	122
113		- if (!debug_lockdep_rcu_enabled())
114		- return 1;
115		- if (!rcu_is_watching())
116		- return 0;
117		- if (!rcu_lockdep_current_cpu_online())
118		- return 0;
119		- if (debug_locks)
120		- lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
121		- return lockdep_opinion \|\| !preemptible();
	123	+ if (rcu_read_lock_held_common(&ret))
	124	+ return ret;
	125	+ return lock_is_held(&rcu_sched_lock_map) \|\| !preemptible();
122	126	}
123	127	EXPORT_SYMBOL(rcu_read_lock_sched_held);
124	128	#endif
..	..	@@ -151,8 +155,7 @@
151	155	*/
152	156	bool rcu_gp_is_expedited(void)
153	157	{
154		- return rcu_expedited \|\| atomic_read(&rcu_expedited_nesting) \|\|
155		- rcu_scheduler_active == RCU_SCHEDULER_INIT;
	158	+ return rcu_expedited \|\| atomic_read(&rcu_expedited_nesting);
156	159	}
157	160	EXPORT_SYMBOL_GPL(rcu_gp_is_expedited);
158	161
..	..	@@ -184,6 +187,8 @@
184	187	}
185	188	EXPORT_SYMBOL_GPL(rcu_unexpedite_gp);
186	189
	190	+static bool rcu_boot_ended __read_mostly;
	191	+
187	192	/*
188	193	* Inform RCU of the end of the in-kernel boot sequence.
189	194	*/
..	..	@@ -192,7 +197,17 @@
192	197	rcu_unexpedite_gp();
193	198	if (rcu_normal_after_boot)
194	199	WRITE_ONCE(rcu_normal, 1);
	200	+ rcu_boot_ended = true;
195	201	}
	202	+
	203	+/*
	204	+ * Let rcutorture know when it is OK to turn it up to eleven.
	205	+ */
	206	+bool rcu_inkernel_boot_has_ended(void)
	207	+{
	208	+ return rcu_boot_ended;
	209	+}
	210	+EXPORT_SYMBOL_GPL(rcu_inkernel_boot_has_ended);
196	211
197	212	#endif /* #ifndef CONFIG_TINY_RCU */
198	213
..	..	@@ -206,11 +221,7 @@
206	221	if (!IS_ENABLED(CONFIG_PROVE_RCU))
207	222	return;
208	223	synchronize_rcu();
209		- synchronize_rcu_bh();
210		- synchronize_sched();
211	224	synchronize_rcu_expedited();
212		- synchronize_rcu_bh_expedited();
213		- synchronize_sched_expedited();
214	225	}
215	226
216	227	#if !defined(CONFIG_TINY_RCU) \|\| defined(CONFIG_SRCU)
..	..	@@ -222,6 +233,7 @@
222	233	{
223	234	rcu_test_sync_prims();
224	235	rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
	236	+ kfree_rcu_scheduler_running();
225	237	rcu_test_sync_prims();
226	238	return 0;
227	239	}
..	..	@@ -231,32 +243,44 @@
231	243
232	244	#ifdef CONFIG_DEBUG_LOCK_ALLOC
233	245	static struct lock_class_key rcu_lock_key;
234		-struct lockdep_map rcu_lock_map =
235		- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
	246	+struct lockdep_map rcu_lock_map = {
	247	+ .name = "rcu_read_lock",
	248	+ .key = &rcu_lock_key,
	249	+ .wait_type_outer = LD_WAIT_FREE,
	250	+ .wait_type_inner = LD_WAIT_CONFIG, /* XXX PREEMPT_RCU ? */
	251	+};
236	252	EXPORT_SYMBOL_GPL(rcu_lock_map);
237	253
238	254	static struct lock_class_key rcu_bh_lock_key;
239		-struct lockdep_map rcu_bh_lock_map =
240		- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
	255	+struct lockdep_map rcu_bh_lock_map = {
	256	+ .name = "rcu_read_lock_bh",
	257	+ .key = &rcu_bh_lock_key,
	258	+ .wait_type_outer = LD_WAIT_FREE,
	259	+ .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_LOCK also makes BH preemptible */
	260	+};
241	261	EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
242	262
243	263	static struct lock_class_key rcu_sched_lock_key;
244		-struct lockdep_map rcu_sched_lock_map =
245		- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
	264	+struct lockdep_map rcu_sched_lock_map = {
	265	+ .name = "rcu_read_lock_sched",
	266	+ .key = &rcu_sched_lock_key,
	267	+ .wait_type_outer = LD_WAIT_FREE,
	268	+ .wait_type_inner = LD_WAIT_SPIN,
	269	+};
246	270	EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
247	271
	272	+// Tell lockdep when RCU callbacks are being invoked.
248	273	static struct lock_class_key rcu_callback_key;
249	274	struct lockdep_map rcu_callback_map =
250	275	STATIC_LOCKDEP_MAP_INIT("rcu_callback", &rcu_callback_key);
251	276	EXPORT_SYMBOL_GPL(rcu_callback_map);
252	277
253		-int notrace debug_lockdep_rcu_enabled(void)
	278	+noinstr int notrace debug_lockdep_rcu_enabled(void)
254	279	{
255		- return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && debug_locks &&
	280	+ return rcu_scheduler_active != RCU_SCHEDULER_INACTIVE && READ_ONCE(debug_locks) &&
256	281	current->lockdep_recursion == 0;
257	282	}
258	283	EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
259		-NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
260	284
261	285	/**
262	286	* rcu_read_lock_held() - might we be in RCU read-side critical section?
..	..	@@ -280,17 +304,14 @@
280	304	*/
281	305	int rcu_read_lock_held(void)
282	306	{
283		- if (!debug_lockdep_rcu_enabled())
284		- return 1;
285		- if (!rcu_is_watching())
286		- return 0;
287		- if (!rcu_lockdep_current_cpu_online())
288		- return 0;
	307	+ bool ret;
	308	+
	309	+ if (rcu_read_lock_held_common(&ret))
	310	+ return ret;
289	311	return lock_is_held(&rcu_lock_map);
290	312	}
291	313	EXPORT_SYMBOL_GPL(rcu_read_lock_held);
292	314
293		-#ifndef CONFIG_PREEMPT_RT_FULL
294	315	/**
295	316	* rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
296	317	*
..	..	@@ -303,21 +324,32 @@
303	324	*
304	325	* Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
305	326	*
306		- * Note that rcu_read_lock() is disallowed if the CPU is either idle or
	327	+ * Note that rcu_read_lock_bh() is disallowed if the CPU is either idle or
307	328	* offline from an RCU perspective, so check for those as well.
308	329	*/
309	330	int rcu_read_lock_bh_held(void)
310	331	{
311		- if (!debug_lockdep_rcu_enabled())
312		- return 1;
313		- if (!rcu_is_watching())
314		- return 0;
315		- if (!rcu_lockdep_current_cpu_online())
316		- return 0;
	332	+ bool ret;
	333	+
	334	+ if (rcu_read_lock_held_common(&ret))
	335	+ return ret;
317	336	return in_softirq() \|\| irqs_disabled();
318	337	}
319	338	EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
320		-#endif
	339	+
	340	+int rcu_read_lock_any_held(void)
	341	+{
	342	+ bool ret;
	343	+
	344	+ if (rcu_read_lock_held_common(&ret))
	345	+ return ret;
	346	+ if (lock_is_held(&rcu_lock_map) \|\|
	347	+ lock_is_held(&rcu_bh_lock_map) \|\|
	348	+ lock_is_held(&rcu_sched_lock_map))
	349	+ return 1;
	350	+ return !preemptible();
	351	+}
	352	+EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
321	353
322	354	#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
323	355
..	..	@@ -342,35 +374,35 @@
342	374	int i;
343	375	int j;
344	376
345		- /* Initialize and register callbacks for each flavor specified. */
	377	+ /* Initialize and register callbacks for each crcu_array element. */
346	378	for (i = 0; i < n; i++) {
347	379	if (checktiny &&
348		- (crcu_array[i] == call_rcu \|\|
349		- crcu_array[i] == call_rcu_bh)) {
	380	+ (crcu_array[i] == call_rcu)) {
350	381	might_sleep();
351	382	continue;
352	383	}
353		- init_rcu_head_on_stack(&rs_array[i].head);
354		- init_completion(&rs_array[i].completion);
355	384	for (j = 0; j < i; j++)
356	385	if (crcu_array[j] == crcu_array[i])
357	386	break;
358		- if (j == i)
	387	+ if (j == i) {
	388	+ init_rcu_head_on_stack(&rs_array[i].head);
	389	+ init_completion(&rs_array[i].completion);
359	390	(crcu_array[i])(&rs_array[i].head, wakeme_after_rcu);
	391	+ }
360	392	}
361	393
362	394	/* Wait for all callbacks to be invoked. */
363	395	for (i = 0; i < n; i++) {
364	396	if (checktiny &&
365		- (crcu_array[i] == call_rcu \|\|
366		- crcu_array[i] == call_rcu_bh))
	397	+ (crcu_array[i] == call_rcu))
367	398	continue;
368	399	for (j = 0; j < i; j++)
369	400	if (crcu_array[j] == crcu_array[i])
370	401	break;
371		- if (j == i)
	402	+ if (j == i) {
372	403	wait_for_completion(&rs_array[i].completion);
373		- destroy_rcu_head_on_stack(&rs_array[i].head);
	404	+ destroy_rcu_head_on_stack(&rs_array[i].head);
	405	+ }
374	406	}
375	407	}
376	408	EXPORT_SYMBOL_GPL(__wait_rcu_gp);
..	..	@@ -426,14 +458,14 @@
426	458	}
427	459	EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
428	460
429		-struct debug_obj_descr rcuhead_debug_descr = {
	461	+const struct debug_obj_descr rcuhead_debug_descr = {
430	462	.name = "rcu_head",
431	463	.is_static_object = rcuhead_is_static_object,
432	464	};
433	465	EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
434	466	#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
435	467
436		-#if defined(CONFIG_TREE_RCU) \|\| defined(CONFIG_PREEMPT_RCU) \|\| defined(CONFIG_RCU_TRACE)
	468	+#if defined(CONFIG_TREE_RCU) \|\| defined(CONFIG_RCU_TRACE)
437	469	void do_trace_rcu_torture_read(const char rcutorturename, struct rcu_head rhp,
438	470	unsigned long secs,
439	471	unsigned long c_old, unsigned long c)
..	..	@@ -446,445 +478,42 @@
446	478	do { } while (0)
447	479	#endif
448	480
449		-#ifdef CONFIG_RCU_STALL_COMMON
	481	+#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) \|\| IS_MODULE(CONFIG_RCU_TORTURE_TEST)
	482	+/* Get rcutorture access to sched_setaffinity(). */
	483	+long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
	484	+{
	485	+ int ret;
450	486
451		-#ifdef CONFIG_PROVE_RCU
452		-#define RCU_STALL_DELAY_DELTA (5 * HZ)
453		-#else
454		-#define RCU_STALL_DELAY_DELTA 0
	487	+ ret = sched_setaffinity(pid, in_mask);
	488	+ WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret);
	489	+ return ret;
	490	+}
	491	+EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity);
455	492	#endif
456	493
457		-int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
	494	+#ifdef CONFIG_RCU_STALL_COMMON
	495	+int rcu_cpu_stall_ftrace_dump __read_mostly;
	496	+module_param(rcu_cpu_stall_ftrace_dump, int, 0644);
	497	+int rcu_cpu_stall_suppress __read_mostly; // !0 = suppress stall warnings.
458	498	EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress);
459		-static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
460		-
461	499	module_param(rcu_cpu_stall_suppress, int, 0644);
	500	+int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
462	501	module_param(rcu_cpu_stall_timeout, int, 0644);
463		-
464		-int rcu_jiffies_till_stall_check(void)
465		-{
466		- int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout);
467		-
468		- /*
469		- * Limit check must be consistent with the Kconfig limits
470		- * for CONFIG_RCU_CPU_STALL_TIMEOUT.
471		- */
472		- if (till_stall_check < 3) {
473		- WRITE_ONCE(rcu_cpu_stall_timeout, 3);
474		- till_stall_check = 3;
475		- } else if (till_stall_check > 300) {
476		- WRITE_ONCE(rcu_cpu_stall_timeout, 300);
477		- till_stall_check = 300;
478		- }
479		- return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
480		-}
481		-
482		-void rcu_sysrq_start(void)
483		-{
484		- if (!rcu_cpu_stall_suppress)
485		- rcu_cpu_stall_suppress = 2;
486		-}
487		-
488		-void rcu_sysrq_end(void)
489		-{
490		- if (rcu_cpu_stall_suppress == 2)
491		- rcu_cpu_stall_suppress = 0;
492		-}
493		-
494		-static int rcu_panic(struct notifier_block this, unsigned long ev, void ptr)
495		-{
496		- rcu_cpu_stall_suppress = 1;
497		- return NOTIFY_DONE;
498		-}
499		-
500		-static struct notifier_block rcu_panic_block = {
501		- .notifier_call = rcu_panic,
502		-};
503		-
504		-static int __init check_cpu_stall_init(void)
505		-{
506		- atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
507		- return 0;
508		-}
509		-early_initcall(check_cpu_stall_init);
510		-
511	502	#endif /* #ifdef CONFIG_RCU_STALL_COMMON */
512	503
513		-#ifdef CONFIG_TASKS_RCU
514		-
515		-/*
516		- * Simple variant of RCU whose quiescent states are voluntary context
517		- * switch, cond_resched_rcu_qs(), user-space execution, and idle.
518		- * As such, grace periods can take one good long time. There are no
519		- * read-side primitives similar to rcu_read_lock() and rcu_read_unlock()
520		- * because this implementation is intended to get the system into a safe
521		- * state for some of the manipulations involved in tracing and the like.
522		- * Finally, this implementation does not support high call_rcu_tasks()
523		- * rates from multiple CPUs. If this is required, per-CPU callback lists
524		- * will be needed.
525		- */
526		-
527		-/* Global list of callbacks and associated lock. */
528		-static struct rcu_head *rcu_tasks_cbs_head;
529		-static struct rcu_head **rcu_tasks_cbs_tail = &rcu_tasks_cbs_head;
530		-static DECLARE_WAIT_QUEUE_HEAD(rcu_tasks_cbs_wq);
531		-static DEFINE_RAW_SPINLOCK(rcu_tasks_cbs_lock);
532		-
533		-/* Track exiting tasks in order to allow them to be waited for. */
534		-DEFINE_STATIC_SRCU(tasks_rcu_exit_srcu);
535		-
536		-/* Control stall timeouts. Disable with <= 0, otherwise jiffies till stall. */
537		-#define RCU_TASK_STALL_TIMEOUT (HZ * 60 * 10)
538		-static int rcu_task_stall_timeout __read_mostly = RCU_TASK_STALL_TIMEOUT;
539		-module_param(rcu_task_stall_timeout, int, 0644);
540		-
541		-static struct task_struct *rcu_tasks_kthread_ptr;
542		-
543		-/**
544		- * call_rcu_tasks() - Queue an RCU for invocation task-based grace period
545		- * @rhp: structure to be used for queueing the RCU updates.
546		- * @func: actual callback function to be invoked after the grace period
547		- *
548		- * The callback function will be invoked some time after a full grace
549		- * period elapses, in other words after all currently executing RCU
550		- * read-side critical sections have completed. call_rcu_tasks() assumes
551		- * that the read-side critical sections end at a voluntary context
552		- * switch (not a preemption!), cond_resched_rcu_qs(), entry into idle,
553		- * or transition to usermode execution. As such, there are no read-side
554		- * primitives analogous to rcu_read_lock() and rcu_read_unlock() because
555		- * this primitive is intended to determine that all tasks have passed
556		- * through a safe state, not so much for data-strcuture synchronization.
557		- *
558		- * See the description of call_rcu() for more detailed information on
559		- * memory ordering guarantees.
560		- */
561		-void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
562		-{
563		- unsigned long flags;
564		- bool needwake;
565		-
566		- rhp->next = NULL;
567		- rhp->func = func;
568		- raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags);
569		- needwake = !rcu_tasks_cbs_head;
570		- *rcu_tasks_cbs_tail = rhp;
571		- rcu_tasks_cbs_tail = &rhp->next;
572		- raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
573		- /* We can't create the thread unless interrupts are enabled. */
574		- if (needwake && READ_ONCE(rcu_tasks_kthread_ptr))
575		- wake_up(&rcu_tasks_cbs_wq);
576		-}
577		-EXPORT_SYMBOL_GPL(call_rcu_tasks);
578		-
579		-/**
580		- * synchronize_rcu_tasks - wait until an rcu-tasks grace period has elapsed.
581		- *
582		- * Control will return to the caller some time after a full rcu-tasks
583		- * grace period has elapsed, in other words after all currently
584		- * executing rcu-tasks read-side critical sections have elapsed. These
585		- * read-side critical sections are delimited by calls to schedule(),
586		- * cond_resched_tasks_rcu_qs(), idle execution, userspace execution, calls
587		- * to synchronize_rcu_tasks(), and (in theory, anyway) cond_resched().
588		- *
589		- * This is a very specialized primitive, intended only for a few uses in
590		- * tracing and other situations requiring manipulation of function
591		- * preambles and profiling hooks. The synchronize_rcu_tasks() function
592		- * is not (yet) intended for heavy use from multiple CPUs.
593		- *
594		- * Note that this guarantee implies further memory-ordering guarantees.
595		- * On systems with more than one CPU, when synchronize_rcu_tasks() returns,
596		- * each CPU is guaranteed to have executed a full memory barrier since the
597		- * end of its last RCU-tasks read-side critical section whose beginning
598		- * preceded the call to synchronize_rcu_tasks(). In addition, each CPU
599		- * having an RCU-tasks read-side critical section that extends beyond
600		- * the return from synchronize_rcu_tasks() is guaranteed to have executed
601		- * a full memory barrier after the beginning of synchronize_rcu_tasks()
602		- * and before the beginning of that RCU-tasks read-side critical section.
603		- * Note that these guarantees include CPUs that are offline, idle, or
604		- * executing in user mode, as well as CPUs that are executing in the kernel.
605		- *
606		- * Furthermore, if CPU A invoked synchronize_rcu_tasks(), which returned
607		- * to its caller on CPU B, then both CPU A and CPU B are guaranteed
608		- * to have executed a full memory barrier during the execution of
609		- * synchronize_rcu_tasks() -- even if CPU A and CPU B are the same CPU
610		- * (but again only if the system has more than one CPU).
611		- */
612		-void synchronize_rcu_tasks(void)
613		-{
614		- /* Complain if the scheduler has not started. */
615		- RCU_LOCKDEP_WARN(rcu_scheduler_active == RCU_SCHEDULER_INACTIVE,
616		- "synchronize_rcu_tasks called too soon");
617		-
618		- /* Wait for the grace period. */
619		- wait_rcu_gp(call_rcu_tasks);
620		-}
621		-EXPORT_SYMBOL_GPL(synchronize_rcu_tasks);
622		-
623		-/**
624		- * rcu_barrier_tasks - Wait for in-flight call_rcu_tasks() callbacks.
625		- *
626		- * Although the current implementation is guaranteed to wait, it is not
627		- * obligated to, for example, if there are no pending callbacks.
628		- */
629		-void rcu_barrier_tasks(void)
630		-{
631		- /* There is only one callback queue, so this is easy. ;-) */
632		- synchronize_rcu_tasks();
633		-}
634		-EXPORT_SYMBOL_GPL(rcu_barrier_tasks);
635		-
636		-/* See if tasks are still holding out, complain if so. */
637		-static void check_holdout_task(struct task_struct *t,
638		- bool needreport, bool *firstreport)
639		-{
640		- int cpu;
641		-
642		- if (!READ_ONCE(t->rcu_tasks_holdout) \|\|
643		- t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) \|\|
644		- !READ_ONCE(t->on_rq) \|\|
645		- (IS_ENABLED(CONFIG_NO_HZ_FULL) &&
646		- !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) {
647		- WRITE_ONCE(t->rcu_tasks_holdout, false);
648		- list_del_init(&t->rcu_tasks_holdout_list);
649		- put_task_struct(t);
650		- return;
651		- }
652		- rcu_request_urgent_qs_task(t);
653		- if (!needreport)
654		- return;
655		- if (*firstreport) {
656		- pr_err("INFO: rcu_tasks detected stalls on tasks:\n");
657		- *firstreport = false;
658		- }
659		- cpu = task_cpu(t);
660		- pr_alert("%p: %c%c nvcsw: %lu/%lu holdout: %d idle_cpu: %d/%d\n",
661		- t, ".I"[is_idle_task(t)],
662		- "N."[cpu < 0 \|\| !tick_nohz_full_cpu(cpu)],
663		- t->rcu_tasks_nvcsw, t->nvcsw, t->rcu_tasks_holdout,
664		- t->rcu_tasks_idle_cpu, cpu);
665		- sched_show_task(t);
666		-}
667		-
668		-/* RCU-tasks kthread that detects grace periods and invokes callbacks. */
669		-static int __noreturn rcu_tasks_kthread(void *arg)
670		-{
671		- unsigned long flags;
672		- struct task_struct g, t;
673		- unsigned long lastreport;
674		- struct rcu_head *list;
675		- struct rcu_head *next;
676		- LIST_HEAD(rcu_tasks_holdouts);
677		- int fract;
678		-
679		- /* Run on housekeeping CPUs by default. Sysadm can move if desired. */
680		- housekeeping_affine(current, HK_FLAG_RCU);
681		-
682		- /*
683		- * Each pass through the following loop makes one check for
684		- * newly arrived callbacks, and, if there are some, waits for
685		- * one RCU-tasks grace period and then invokes the callbacks.
686		- * This loop is terminated by the system going down. ;-)
687		- */
688		- for (;;) {
689		-
690		- /* Pick up any new callbacks. */
691		- raw_spin_lock_irqsave(&rcu_tasks_cbs_lock, flags);
692		- list = rcu_tasks_cbs_head;
693		- rcu_tasks_cbs_head = NULL;
694		- rcu_tasks_cbs_tail = &rcu_tasks_cbs_head;
695		- raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
696		-
697		- /* If there were none, wait a bit and start over. */
698		- if (!list) {
699		- wait_event_interruptible(rcu_tasks_cbs_wq,
700		- rcu_tasks_cbs_head);
701		- if (!rcu_tasks_cbs_head) {
702		- WARN_ON(signal_pending(current));
703		- schedule_timeout_interruptible(HZ/10);
704		- }
705		- continue;
706		- }
707		-
708		- /*
709		- * Wait for all pre-existing t->on_rq and t->nvcsw
710		- * transitions to complete. Invoking synchronize_sched()
711		- * suffices because all these transitions occur with
712		- * interrupts disabled. Without this synchronize_sched(),
713		- * a read-side critical section that started before the
714		- * grace period might be incorrectly seen as having started
715		- * after the grace period.
716		- *
717		- * This synchronize_sched() also dispenses with the
718		- * need for a memory barrier on the first store to
719		- * ->rcu_tasks_holdout, as it forces the store to happen
720		- * after the beginning of the grace period.
721		- */
722		- synchronize_sched();
723		-
724		- /*
725		- * There were callbacks, so we need to wait for an
726		- * RCU-tasks grace period. Start off by scanning
727		- * the task list for tasks that are not already
728		- * voluntarily blocked. Mark these tasks and make
729		- * a list of them in rcu_tasks_holdouts.
730		- */
731		- rcu_read_lock();
732		- for_each_process_thread(g, t) {
733		- if (t != current && READ_ONCE(t->on_rq) &&
734		- !is_idle_task(t)) {
735		- get_task_struct(t);
736		- t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw);
737		- WRITE_ONCE(t->rcu_tasks_holdout, true);
738		- list_add(&t->rcu_tasks_holdout_list,
739		- &rcu_tasks_holdouts);
740		- }
741		- }
742		- rcu_read_unlock();
743		-
744		- /*
745		- * Wait for tasks that are in the process of exiting.
746		- * This does only part of the job, ensuring that all
747		- * tasks that were previously exiting reach the point
748		- * where they have disabled preemption, allowing the
749		- * later synchronize_sched() to finish the job.
750		- */
751		- synchronize_srcu(&tasks_rcu_exit_srcu);
752		-
753		- /*
754		- * Each pass through the following loop scans the list
755		- * of holdout tasks, removing any that are no longer
756		- * holdouts. When the list is empty, we are done.
757		- */
758		- lastreport = jiffies;
759		-
760		- /* Start off with HZ/10 wait and slowly back off to 1 HZ wait*/
761		- fract = 10;
762		-
763		- for (;;) {
764		- bool firstreport;
765		- bool needreport;
766		- int rtst;
767		- struct task_struct *t1;
768		-
769		- if (list_empty(&rcu_tasks_holdouts))
770		- break;
771		-
772		- /* Slowly back off waiting for holdouts */
773		- schedule_timeout_interruptible(HZ/fract);
774		-
775		- if (fract > 1)
776		- fract--;
777		-
778		- rtst = READ_ONCE(rcu_task_stall_timeout);
779		- needreport = rtst > 0 &&
780		- time_after(jiffies, lastreport + rtst);
781		- if (needreport)
782		- lastreport = jiffies;
783		- firstreport = true;
784		- WARN_ON(signal_pending(current));
785		- list_for_each_entry_safe(t, t1, &rcu_tasks_holdouts,
786		- rcu_tasks_holdout_list) {
787		- check_holdout_task(t, needreport, &firstreport);
788		- cond_resched();
789		- }
790		- }
791		-
792		- /*
793		- * Because ->on_rq and ->nvcsw are not guaranteed
794		- * to have a full memory barriers prior to them in the
795		- * schedule() path, memory reordering on other CPUs could
796		- * cause their RCU-tasks read-side critical sections to
797		- * extend past the end of the grace period. However,
798		- * because these ->nvcsw updates are carried out with
799		- * interrupts disabled, we can use synchronize_sched()
800		- * to force the needed ordering on all such CPUs.
801		- *
802		- * This synchronize_sched() also confines all
803		- * ->rcu_tasks_holdout accesses to be within the grace
804		- * period, avoiding the need for memory barriers for
805		- * ->rcu_tasks_holdout accesses.
806		- *
807		- * In addition, this synchronize_sched() waits for exiting
808		- * tasks to complete their final preempt_disable() region
809		- * of execution, cleaning up after the synchronize_srcu()
810		- * above.
811		- */
812		- synchronize_sched();
813		-
814		- /* Invoke the callbacks. */
815		- while (list) {
816		- next = list->next;
817		- local_bh_disable();
818		- list->func(list);
819		- local_bh_enable();
820		- list = next;
821		- cond_resched();
822		- }
823		- /* Paranoid sleep to keep this from entering a tight loop */
824		- schedule_timeout_uninterruptible(HZ/10);
825		- }
826		-}
827		-
828		-/* Spawn rcu_tasks_kthread() at core_initcall() time. */
829		-static int __init rcu_spawn_tasks_kthread(void)
830		-{
831		- struct task_struct *t;
832		-
833		- t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread");
834		- BUG_ON(IS_ERR(t));
835		- smp_mb(); /* Ensure others see full kthread. */
836		- WRITE_ONCE(rcu_tasks_kthread_ptr, t);
837		- return 0;
838		-}
839		-core_initcall(rcu_spawn_tasks_kthread);
840		-
841		-/* Do the srcu_read_lock() for the above synchronize_srcu(). */
842		-void exit_tasks_rcu_start(void)
843		-{
844		- preempt_disable();
845		- current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
846		- preempt_enable();
847		-}
848		-
849		-/* Do the srcu_read_unlock() for the above synchronize_srcu(). */
850		-void exit_tasks_rcu_finish(void)
851		-{
852		- preempt_disable();
853		- __srcu_read_unlock(&tasks_rcu_exit_srcu, current->rcu_tasks_idx);
854		- preempt_enable();
855		-}
856		-
857		-#endif /* #ifdef CONFIG_TASKS_RCU */
858		-
859		-#ifndef CONFIG_TINY_RCU
860		-
861		-/*
862		- * Print any non-default Tasks RCU settings.
863		- */
864		-static void __init rcu_tasks_bootup_oddness(void)
865		-{
866		-#ifdef CONFIG_TASKS_RCU
867		- if (rcu_task_stall_timeout != RCU_TASK_STALL_TIMEOUT)
868		- pr_info("\tTasks-RCU CPU stall warnings timeout set to %d (rcu_task_stall_timeout).\n", rcu_task_stall_timeout);
869		- else
870		- pr_info("\tTasks RCU enabled.\n");
871		-#endif /* #ifdef CONFIG_TASKS_RCU */
872		-}
873		-
874		-#endif /* #ifndef CONFIG_TINY_RCU */
	504	+// Suppress boot-time RCU CPU stall warnings and rcutorture writer stall
	505	+// warnings. Also used by rcutorture even if stall warnings are excluded.
	506	+int rcu_cpu_stall_suppress_at_boot __read_mostly; // !0 = suppress boot stalls.
	507	+EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress_at_boot);
	508	+module_param(rcu_cpu_stall_suppress_at_boot, int, 0444);
875	509
876	510	#ifdef CONFIG_PROVE_RCU
877	511
878	512	/*
879		- * Early boot self test parameters, one for each flavor
	513	+ * Early boot self test parameters.
880	514	*/
881	515	static bool rcu_self_test;
882		-static bool rcu_self_test_bh;
883		-static bool rcu_self_test_sched;
884		-
885	516	module_param(rcu_self_test, bool, 0444);
886		-module_param(rcu_self_test_bh, bool, 0444);
887		-module_param(rcu_self_test_sched, bool, 0444);
888	517
889	518	static int rcu_self_test_counter;
890	519
..	..	@@ -894,25 +523,24 @@
894	523	pr_info("RCU test callback executed %d\n", rcu_self_test_counter);
895	524	}
896	525
	526	+DEFINE_STATIC_SRCU(early_srcu);
	527	+
	528	+struct early_boot_kfree_rcu {
	529	+ struct rcu_head rh;
	530	+};
	531	+
897	532	static void early_boot_test_call_rcu(void)
898	533	{
899	534	static struct rcu_head head;
	535	+ static struct rcu_head shead;
	536	+ struct early_boot_kfree_rcu *rhp;
900	537
901	538	call_rcu(&head, test_callback);
902		-}
903		-
904		-static void early_boot_test_call_rcu_bh(void)
905		-{
906		- static struct rcu_head head;
907		-
908		- call_rcu_bh(&head, test_callback);
909		-}
910		-
911		-static void early_boot_test_call_rcu_sched(void)
912		-{
913		- static struct rcu_head head;
914		-
915		- call_rcu_sched(&head, test_callback);
	539	+ if (IS_ENABLED(CONFIG_SRCU))
	540	+ call_srcu(&early_srcu, &shead, test_callback);
	541	+ rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
	542	+ if (!WARN_ON_ONCE(!rhp))
	543	+ kfree_rcu(rhp, rh);
916	544	}
917	545
918	546	void rcu_early_boot_tests(void)
..	..	@@ -921,10 +549,6 @@
921	549
922	550	if (rcu_self_test)
923	551	early_boot_test_call_rcu();
924		- if (rcu_self_test_bh)
925		- early_boot_test_call_rcu_bh();
926		- if (rcu_self_test_sched)
927		- early_boot_test_call_rcu_sched();
928	552	rcu_test_sync_prims();
929	553	}
930	554
..	..	@@ -936,16 +560,11 @@
936	560	if (rcu_self_test) {
937	561	early_boot_test_counter++;
938	562	rcu_barrier();
	563	+ if (IS_ENABLED(CONFIG_SRCU)) {
	564	+ early_boot_test_counter++;
	565	+ srcu_barrier(&early_srcu);
	566	+ }
939	567	}
940		- if (rcu_self_test_bh) {
941		- early_boot_test_counter++;
942		- rcu_barrier_bh();
943		- }
944		- if (rcu_self_test_sched) {
945		- early_boot_test_counter++;
946		- rcu_barrier_sched();
947		- }
948		-
949	568	if (rcu_self_test_counter != early_boot_test_counter) {
950	569	WARN_ON(1);
951	570	ret = -1;
..	..	@@ -958,6 +577,8 @@
958	577	void rcu_early_boot_tests(void) {}
959	578	#endif /* CONFIG_PROVE_RCU */
960	579
	580	+#include "tasks.h"
	581	+
961	582	#ifndef CONFIG_TINY_RCU
962	583
963	584	/*