Merge tag 'rcu.release.v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Neeraj Upadhyay:
 "Context tracking:
   - rename context tracking state related symbols and remove references
     to "dynticks" in various context tracking state variables and
     related helpers
   - force context_tracking_enabled_this_cpu() to be inlined to avoid
     leaving a noinstr section

  CSD lock:
   - enhance CSD-lock diagnostic reports
   - add an API to provide an indication of ongoing CSD-lock stall

  nocb:
   - update and simplify RCU nocb code to handle (de-)offloading of
     callbacks only for offline CPUs
   - fix RT throttling hrtimer being armed from offline CPU

  rcutorture:
   - remove redundant rcu_torture_ops get_gp_completed fields
   - add SRCU ->same_gp_state and ->get_comp_state functions
   - add generic test for NUM_ACTIVE_*RCU_POLL* for testing RCU and SRCU
     polled grace periods
   - add CFcommon.arch for arch-specific Kconfig options
   - print number of update types in rcu_torture_write_types()
   - add rcutree.nohz_full_patience_delay testing to the TREE07 scenario
   - add a stall_cpu_repeat module parameter to test repeated CPU stalls
   - add argument to limit number of CPUs a guest OS can use in
     torture.sh

  rcustall:
   - abbreviate RCU CPU stall warnings during CSD-lock stalls
   - Allow dump_cpu_task() to be called without disabling preemption
   - defer printing stall-warning backtrace when holding rcu_node lock

  srcu:
   - make SRCU gp seq wrap-around faster
   - add KCSAN checks for concurrent updates to ->srcu_n_exp_nodelay and
     ->reschedule_count which are used in heuristics governing
     auto-expediting of normal SRCU grace periods and
     grace-period-state-machine delays
   - mark idle SRCU-barrier callbacks to help identify stuck
     SRCU-barrier callback

  rcu tasks:
   - remove RCU Tasks Rude asynchronous APIs as they are no longer used
   - stop testing RCU Tasks Rude asynchronous APIs
   - fix access to non-existent percpu regions
   - check processor-ID assumptions during chosen CPU calculation for
     callback enqueuing
   - update description of rtp->tasks_gp_seq grace-period sequence
     number
   - add rcu_barrier_cb_is_done() to identify whether a given
     rcu_barrier callback is stuck
   - mark idle Tasks-RCU-barrier callbacks
   - add *torture_stats_print() functions to print detailed diagnostics
     for Tasks-RCU variants
   - capture start time of rcu_barrier_tasks*() operation to help
     distinguish a hung barrier operation from a long series of barrier
     operations

  refscale:
   - add a TINY scenario to support tests of Tiny RCU and Tiny
     SRCU
   - optimize process_durations() operation

  rcuscale:
   - dump stacks of stalled rcu_scale_writer() instances and
     grace-period statistics when rcu_scale_writer() stalls
   - mark idle RCU-barrier callbacks to identify stuck RCU-barrier
     callbacks
   - print detailed grace-period and barrier diagnostics on
     rcu_scale_writer() hangs for Tasks-RCU variants
   - warn if async module parameter is specified for RCU implementations
     that do not have async primitives such as RCU Tasks Rude
   - make all writer tasks report upon hang
   - tolerate repeated GFP_KERNEL failure in rcu_scale_writer()
   - use special allocator for rcu_scale_writer()
   - NULL out top-level pointers to heap memory to avoid double-free
     bugs on modprobe failures
   - maintain per-task instead of per-CPU callbacks count to avoid any
     issues with migration of either tasks or callbacks
   - constify struct ref_scale_ops

  Fixes:
   - use system_unbound_wq for kfree_rcu work to avoid disturbing
     isolated CPUs

  Misc:
   - warn on unexpected rcu_state.srs_done_tail state
   - better define "atomic" for list_replace_rcu() and
     hlist_replace_rcu() routines
   - annotate struct kvfree_rcu_bulk_data with __counted_by()"

* tag 'rcu.release.v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (90 commits)
  rcu: Defer printing stall-warning backtrace when holding rcu_node lock
  rcu/nocb: Remove superfluous memory barrier after bypass enqueue
  rcu/nocb: Conditionally wake up rcuo if not already waiting on GP
  rcu/nocb: Fix RT throttling hrtimer armed from offline CPU
  rcu/nocb: Simplify (de-)offloading state machine
  context_tracking: Tag context_tracking_enabled_this_cpu() __always_inline
  context_tracking, rcu: Rename rcu_dyntick trace event into rcu_watching
  rcu: Update stray documentation references to rcu_dynticks_eqs_{enter, exit}()
  rcu: Rename rcu_momentary_dyntick_idle() into rcu_momentary_eqs()
  rcu: Rename rcu_implicit_dynticks_qs() into rcu_watching_snap_recheck()
  rcu: Rename dyntick_save_progress_counter() into rcu_watching_snap_save()
  rcu: Rename struct rcu_data .exp_dynticks_snap into .exp_watching_snap
  rcu: Rename struct rcu_data .dynticks_snap into .watching_snap
  rcu: Rename rcu_dynticks_zero_in_eqs() into rcu_watching_zero_in_eqs()
  rcu: Rename rcu_dynticks_in_eqs_since() into rcu_watching_snap_stopped_since()
  rcu: Rename rcu_dynticks_in_eqs() into rcu_watching_snap_in_eqs()
  rcu: Rename rcu_dynticks_eqs_online() into rcu_watching_online()
  context_tracking, rcu: Rename rcu_dynticks_curr_cpu_in_eqs() into rcu_is_watching_curr_cpu()
  context_tracking, rcu: Rename rcu_dynticks_task*() into rcu_task*()
  refscale: Constify struct ref_scale_ops
  ...

1 files changed, 143 insertions, 71 deletions

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index ba3440a45b6d..6333f4ccf024 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -34,6 +34,7 @@ typedef void (*postgp_func_t)(struct rcu_tasks *rtp);
  * @rtp_blkd_tasks: List of tasks blocked as readers.
  * @rtp_exit_list: List of tasks in the latter portion of do_exit().
  * @cpu: CPU number corresponding to this entry.
+ * @index: Index of this CPU in rtpcp_array of the rcu_tasks structure.
  * @rtpp: Pointer to the rcu_tasks structure.
  */
 struct rcu_tasks_percpu {
@@ -49,6 +50,7 @@ struct rcu_tasks_percpu {
 	struct list_head rtp_blkd_tasks;
 	struct list_head rtp_exit_list;
 	int cpu;
+	int index;
 	struct rcu_tasks *rtpp;
 };
 
@@ -63,7 +65,7 @@ struct rcu_tasks_percpu {
  * @init_fract: Initial backoff sleep interval.
  * @gp_jiffies: Time of last @gp_state transition.
  * @gp_start: Most recent grace-period start in jiffies.
- * @tasks_gp_seq: Number of grace periods completed since boot.
+ * @tasks_gp_seq: Number of grace periods completed since boot in upper bits.
  * @n_ipis: Number of IPIs sent to encourage grace periods to end.
  * @n_ipis_fails: Number of IPI-send failures.
  * @kthread_ptr: This flavor's grace-period/callback-invocation kthread.
@@ -76,6 +78,7 @@ struct rcu_tasks_percpu {
  * @call_func: This flavor's call_rcu()-equivalent function.
  * @wait_state: Task state for synchronous grace-period waits (default TASK_UNINTERRUPTIBLE).
  * @rtpcpu: This flavor's rcu_tasks_percpu structure.
+ * @rtpcp_array: Array of pointers to rcu_tasks_percpu structure of CPUs in cpu_possible_mask.
  * @percpu_enqueue_shift: Shift down CPU ID this much when enqueuing callbacks.
  * @percpu_enqueue_lim: Number of per-CPU callback queues in use for enqueuing.
  * @percpu_dequeue_lim: Number of per-CPU callback queues in use for dequeuing.
@@ -84,6 +87,7 @@ struct rcu_tasks_percpu {
  * @barrier_q_count: Number of queues being waited on.
  * @barrier_q_completion: Barrier wait/wakeup mechanism.
  * @barrier_q_seq: Sequence number for barrier operations.
+ * @barrier_q_start: Most recent barrier start in jiffies.
  * @name: This flavor's textual name.
  * @kname: This flavor's kthread name.
  */
@@ -110,6 +114,7 @@ struct rcu_tasks {
 	call_rcu_func_t call_func;
 	unsigned int wait_state;
 	struct rcu_tasks_percpu __percpu *rtpcpu;
+	struct rcu_tasks_percpu **rtpcp_array;
 	int percpu_enqueue_shift;
 	int percpu_enqueue_lim;
 	int percpu_dequeue_lim;
@@ -118,6 +123,7 @@ struct rcu_tasks {
 	atomic_t barrier_q_count;
 	struct completion barrier_q_completion;
 	unsigned long barrier_q_seq;
+	unsigned long barrier_q_start;
 	char *name;
 	char *kname;
 };
@@ -182,6 +188,8 @@ module_param(rcu_task_collapse_lim, int, 0444);
 static int rcu_task_lazy_lim __read_mostly = 32;
 module_param(rcu_task_lazy_lim, int, 0444);
 
+static int rcu_task_cpu_ids;
+
 /* RCU tasks grace-period state for debugging. */
 #define RTGS_INIT		 0
 #define RTGS_WAIT_WAIT_CBS	 1
@@ -245,6 +253,8 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
 	int cpu;
 	int lim;
 	int shift;
+	int maxcpu;
+	int index = 0;
 
 	if (rcu_task_enqueue_lim < 0) {
 		rcu_task_enqueue_lim = 1;
@@ -254,14 +264,9 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
 	}
 	lim = rcu_task_enqueue_lim;
 
-	if (lim > nr_cpu_ids)
-		lim = nr_cpu_ids;
-	shift = ilog2(nr_cpu_ids / lim);
-	if (((nr_cpu_ids - 1) >> shift) >= lim)
-		shift++;
-	WRITE_ONCE(rtp->percpu_enqueue_shift, shift);
-	WRITE_ONCE(rtp->percpu_dequeue_lim, lim);
-	smp_store_release(&rtp->percpu_enqueue_lim, lim);
+	rtp->rtpcp_array = kcalloc(num_possible_cpus(), sizeof(struct rcu_tasks_percpu *), GFP_KERNEL);
+	BUG_ON(!rtp->rtpcp_array);
+
 	for_each_possible_cpu(cpu) {
 		struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
 
@@ -273,14 +278,30 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
 		INIT_WORK(&rtpcp->rtp_work, rcu_tasks_invoke_cbs_wq);
 		rtpcp->cpu = cpu;
 		rtpcp->rtpp = rtp;
+		rtpcp->index = index;
+		rtp->rtpcp_array[index] = rtpcp;
+		index++;
 		if (!rtpcp->rtp_blkd_tasks.next)
 			INIT_LIST_HEAD(&rtpcp->rtp_blkd_tasks);
 		if (!rtpcp->rtp_exit_list.next)
 			INIT_LIST_HEAD(&rtpcp->rtp_exit_list);
+		rtpcp->barrier_q_head.next = &rtpcp->barrier_q_head;
+		maxcpu = cpu;
 	}
 
-	pr_info("%s: Setting shift to %d and lim to %d rcu_task_cb_adjust=%d.\n", rtp->name,
-			data_race(rtp->percpu_enqueue_shift), data_race(rtp->percpu_enqueue_lim), rcu_task_cb_adjust);
+	rcu_task_cpu_ids = maxcpu + 1;
+	if (lim > rcu_task_cpu_ids)
+		lim = rcu_task_cpu_ids;
+	shift = ilog2(rcu_task_cpu_ids / lim);
+	if (((rcu_task_cpu_ids - 1) >> shift) >= lim)
+		shift++;
+	WRITE_ONCE(rtp->percpu_enqueue_shift, shift);
+	WRITE_ONCE(rtp->percpu_dequeue_lim, lim);
+	smp_store_release(&rtp->percpu_enqueue_lim, lim);
+
+	pr_info("%s: Setting shift to %d and lim to %d rcu_task_cb_adjust=%d rcu_task_cpu_ids=%d.\n",
+			rtp->name, data_race(rtp->percpu_enqueue_shift), data_race(rtp->percpu_enqueue_lim),
+			rcu_task_cb_adjust, rcu_task_cpu_ids);
 }
 
 // Compute wakeup time for lazy callback timer.
@@ -339,6 +360,7 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
 	rcu_read_lock();
 	ideal_cpu = smp_processor_id() >> READ_ONCE(rtp->percpu_enqueue_shift);
 	chosen_cpu = cpumask_next(ideal_cpu - 1, cpu_possible_mask);
+	WARN_ON_ONCE(chosen_cpu >= rcu_task_cpu_ids);
 	rtpcp = per_cpu_ptr(rtp->rtpcpu, chosen_cpu);
 	if (!raw_spin_trylock_rcu_node(rtpcp)) { // irqs already disabled.
 		raw_spin_lock_rcu_node(rtpcp); // irqs already disabled.
@@ -348,7 +370,7 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
 			rtpcp->rtp_n_lock_retries = 0;
 		}
 		if (rcu_task_cb_adjust && ++rtpcp->rtp_n_lock_retries > rcu_task_contend_lim &&
-		    READ_ONCE(rtp->percpu_enqueue_lim) != nr_cpu_ids)
+		    READ_ONCE(rtp->percpu_enqueue_lim) != rcu_task_cpu_ids)
 			needadjust = true;  // Defer adjustment to avoid deadlock.
 	}
 	// Queuing callbacks before initialization not yet supported.
@@ -368,10 +390,10 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
 	raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
 	if (unlikely(needadjust)) {
 		raw_spin_lock_irqsave(&rtp->cbs_gbl_lock, flags);
-		if (rtp->percpu_enqueue_lim != nr_cpu_ids) {
+		if (rtp->percpu_enqueue_lim != rcu_task_cpu_ids) {
 			WRITE_ONCE(rtp->percpu_enqueue_shift, 0);
-			WRITE_ONCE(rtp->percpu_dequeue_lim, nr_cpu_ids);
-			smp_store_release(&rtp->percpu_enqueue_lim, nr_cpu_ids);
+			WRITE_ONCE(rtp->percpu_dequeue_lim, rcu_task_cpu_ids);
+			smp_store_release(&rtp->percpu_enqueue_lim, rcu_task_cpu_ids);
 			pr_info("Switching %s to per-CPU callback queuing.\n", rtp->name);
 		}
 		raw_spin_unlock_irqrestore(&rtp->cbs_gbl_lock, flags);
@@ -388,6 +410,7 @@ static void rcu_barrier_tasks_generic_cb(struct rcu_head *rhp)
 	struct rcu_tasks *rtp;
 	struct rcu_tasks_percpu *rtpcp;
 
+	rhp->next = rhp; // Mark the callback as having been invoked.
 	rtpcp = container_of(rhp, struct rcu_tasks_percpu, barrier_q_head);
 	rtp = rtpcp->rtpp;
 	if (atomic_dec_and_test(&rtp->barrier_q_count))
@@ -396,7 +419,7 @@ static void rcu_barrier_tasks_generic_cb(struct rcu_head *rhp)
 
 // Wait for all in-flight callbacks for the specified RCU Tasks flavor.
 // Operates in a manner similar to rcu_barrier().
-static void rcu_barrier_tasks_generic(struct rcu_tasks *rtp)
+static void __maybe_unused rcu_barrier_tasks_generic(struct rcu_tasks *rtp)
 {
 	int cpu;
 	unsigned long flags;
@@ -409,6 +432,7 @@ static void rcu_barrier_tasks_generic(struct rcu_tasks *rtp)
 		mutex_unlock(&rtp->barrier_q_mutex);
 		return;
 	}
+	rtp->barrier_q_start = jiffies;
 	rcu_seq_start(&rtp->barrier_q_seq);
 	init_completion(&rtp->barrier_q_completion);
 	atomic_set(&rtp->barrier_q_count, 2);
@@ -444,6 +468,8 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
 
 	dequeue_limit = smp_load_acquire(&rtp->percpu_dequeue_lim);
 	for (cpu = 0; cpu < dequeue_limit; cpu++) {
+		if (!cpu_possible(cpu))
+			continue;
 		struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
 
 		/* Advance and accelerate any new callbacks. */
@@ -481,7 +507,7 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
 	if (rcu_task_cb_adjust && ncbs <= rcu_task_collapse_lim) {
 		raw_spin_lock_irqsave(&rtp->cbs_gbl_lock, flags);
 		if (rtp->percpu_enqueue_lim > 1) {
-			WRITE_ONCE(rtp->percpu_enqueue_shift, order_base_2(nr_cpu_ids));
+			WRITE_ONCE(rtp->percpu_enqueue_shift, order_base_2(rcu_task_cpu_ids));
 			smp_store_release(&rtp->percpu_enqueue_lim, 1);
 			rtp->percpu_dequeue_gpseq = get_state_synchronize_rcu();
 			gpdone = false;
@@ -496,7 +522,9 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
 			pr_info("Completing switch %s to CPU-0 callback queuing.\n", rtp->name);
 		}
 		if (rtp->percpu_dequeue_lim == 1) {
-			for (cpu = rtp->percpu_dequeue_lim; cpu < nr_cpu_ids; cpu++) {
+			for (cpu = rtp->percpu_dequeue_lim; cpu < rcu_task_cpu_ids; cpu++) {
+				if (!cpu_possible(cpu))
+					continue;
 				struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
 
 				WARN_ON_ONCE(rcu_segcblist_n_cbs(&rtpcp->cblist));
@@ -511,30 +539,32 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
 // Advance callbacks and invoke any that are ready.
 static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu *rtpcp)
 {
-	int cpu;
-	int cpunext;
 	int cpuwq;
 	unsigned long flags;
 	int len;
+	int index;
 	struct rcu_head *rhp;
 	struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
 	struct rcu_tasks_percpu *rtpcp_next;
 
-	cpu = rtpcp->cpu;
-	cpunext = cpu * 2 + 1;
-	if (cpunext < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
-		rtpcp_next = per_cpu_ptr(rtp->rtpcpu, cpunext);
-		cpuwq = rcu_cpu_beenfullyonline(cpunext) ? cpunext : WORK_CPU_UNBOUND;
-		queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work);
-		cpunext++;
-		if (cpunext < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
-			rtpcp_next = per_cpu_ptr(rtp->rtpcpu, cpunext);
-			cpuwq = rcu_cpu_beenfullyonline(cpunext) ? cpunext : WORK_CPU_UNBOUND;
+	index = rtpcp->index * 2 + 1;
+	if (index < num_possible_cpus()) {
+		rtpcp_next = rtp->rtpcp_array[index];
+		if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
+			cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND;
 			queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work);
+			index++;
+			if (index < num_possible_cpus()) {
+				rtpcp_next = rtp->rtpcp_array[index];
+				if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
+					cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND;
+					queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work);
+				}
+			}
 		}
 	}
 
-	if (rcu_segcblist_empty(&rtpcp->cblist) || !cpu_possible(cpu))
+	if (rcu_segcblist_empty(&rtpcp->cblist))
 		return;
 	raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
 	rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));
@@ -687,9 +717,7 @@ static void __init rcu_tasks_bootup_oddness(void)
 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
 }
 
-#endif /* #ifndef CONFIG_TINY_RCU */
 
-#ifndef CONFIG_TINY_RCU
 /* Dump out rcutorture-relevant state common to all RCU-tasks flavors. */
 static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s)
 {
@@ -723,6 +751,53 @@ static void show_rcu_tasks_generic_gp_kthread(struct rcu_tasks *rtp, char *s)
 		rtp->lazy_jiffies,
 		s);
 }
+
+/* Dump out more rcutorture-relevant state common to all RCU-tasks flavors. */
+static void rcu_tasks_torture_stats_print_generic(struct rcu_tasks *rtp, char *tt,
+						  char *tf, char *tst)
+{
+	cpumask_var_t cm;
+	int cpu;
+	bool gotcb = false;
+	unsigned long j = jiffies;
+
+	pr_alert("%s%s Tasks%s RCU g%ld gp_start %lu gp_jiffies %lu gp_state %d (%s).\n",
+		 tt, tf, tst, data_race(rtp->tasks_gp_seq),
+		 j - data_race(rtp->gp_start), j - data_race(rtp->gp_jiffies),
+		 data_race(rtp->gp_state), tasks_gp_state_getname(rtp));
+	pr_alert("\tEnqueue shift %d limit %d Dequeue limit %d gpseq %lu.\n",
+		 data_race(rtp->percpu_enqueue_shift),
+		 data_race(rtp->percpu_enqueue_lim),
+		 data_race(rtp->percpu_dequeue_lim),
+		 data_race(rtp->percpu_dequeue_gpseq));
+	(void)zalloc_cpumask_var(&cm, GFP_KERNEL);
+	pr_alert("\tCallback counts:");
+	for_each_possible_cpu(cpu) {
+		long n;
+		struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
+
+		if (cpumask_available(cm) && !rcu_barrier_cb_is_done(&rtpcp->barrier_q_head))
+			cpumask_set_cpu(cpu, cm);
+		n = rcu_segcblist_n_cbs(&rtpcp->cblist);
+		if (!n)
+			continue;
+		pr_cont(" %d:%ld", cpu, n);
+		gotcb = true;
+	}
+	if (gotcb)
+		pr_cont(".\n");
+	else
+		pr_cont(" (none).\n");
+	pr_alert("\tBarrier seq %lu start %lu count %d holdout CPUs ",
+		 data_race(rtp->barrier_q_seq), j - data_race(rtp->barrier_q_start),
+		 atomic_read(&rtp->barrier_q_count));
+	if (cpumask_available(cm) && !cpumask_empty(cm))
+		pr_cont(" %*pbl.\n", cpumask_pr_args(cm));
+	else
+		pr_cont("(none).\n");
+	free_cpumask_var(cm);
+}
+
 #endif // #ifndef CONFIG_TINY_RCU
 
 static void exit_tasks_rcu_finish_trace(struct task_struct *t);
@@ -1174,6 +1249,12 @@ void show_rcu_tasks_classic_gp_kthread(void)
 	show_rcu_tasks_generic_gp_kthread(&rcu_tasks, "");
 }
 EXPORT_SYMBOL_GPL(show_rcu_tasks_classic_gp_kthread);
+
+void rcu_tasks_torture_stats_print(char *tt, char *tf)
+{
+	rcu_tasks_torture_stats_print_generic(&rcu_tasks, tt, tf, "");
+}
+EXPORT_SYMBOL_GPL(rcu_tasks_torture_stats_print);
 #endif // !defined(CONFIG_TINY_RCU)
 
 struct task_struct *get_rcu_tasks_gp_kthread(void)
@@ -1244,13 +1325,12 @@ void exit_tasks_rcu_finish(void) { exit_tasks_rcu_finish_trace(current); }
 
 ////////////////////////////////////////////////////////////////////////
 //
-// "Rude" variant of Tasks RCU, inspired by Steve Rostedt's trick of
-// passing an empty function to schedule_on_each_cpu().  This approach
-// provides an asynchronous call_rcu_tasks_rude() API and batching of
-// concurrent calls to the synchronous synchronize_rcu_tasks_rude() API.
-// This invokes schedule_on_each_cpu() in order to send IPIs far and wide
-// and induces otherwise unnecessary context switches on all online CPUs,
-// whether idle or not.
+// "Rude" variant of Tasks RCU, inspired by Steve Rostedt's
+// trick of passing an empty function to schedule_on_each_cpu().
+// This approach provides batching of concurrent calls to the synchronous
+// synchronize_rcu_tasks_rude() API.  This invokes schedule_on_each_cpu()
+// in order to send IPIs far and wide and induces otherwise unnecessary
+// context switches on all online CPUs, whether idle or not.
 //
 // Callback handling is provided by the rcu_tasks_kthread() function.
 //
@@ -1268,11 +1348,11 @@ static void rcu_tasks_rude_wait_gp(struct rcu_tasks *rtp)
 	schedule_on_each_cpu(rcu_tasks_be_rude);
 }
 
-void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func);
+static void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func);
 DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude,
 		 "RCU Tasks Rude");
 
-/**
+/*
  * call_rcu_tasks_rude() - Queue a callback rude task-based grace period
  * @rhp: structure to be used for queueing the RCU updates.
  * @func: actual callback function to be invoked after the grace period
@@ -1289,12 +1369,14 @@ DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude,
  *
  * See the description of call_rcu() for more detailed information on
  * memory ordering guarantees.
+ *
+ * This is no longer exported, and is instead reserved for use by
+ * synchronize_rcu_tasks_rude().
  */
-void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func)
+static void call_rcu_tasks_rude(struct rcu_head *rhp, rcu_callback_t func)
 {
 	call_rcu_tasks_generic(rhp, func, &rcu_tasks_rude);
 }
-EXPORT_SYMBOL_GPL(call_rcu_tasks_rude);
 
 /**
  * synchronize_rcu_tasks_rude - wait for a rude rcu-tasks grace period
@@ -1320,26 +1402,9 @@ void synchronize_rcu_tasks_rude(void)
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu_tasks_rude);
 
-/**
- * rcu_barrier_tasks_rude - Wait for in-flight call_rcu_tasks_rude() callbacks.
- *
- * Although the current implementation is guaranteed to wait, it is not
- * obligated to, for example, if there are no pending callbacks.
- */
-void rcu_barrier_tasks_rude(void)
-{
-	rcu_barrier_tasks_generic(&rcu_tasks_rude);
-}
-EXPORT_SYMBOL_GPL(rcu_barrier_tasks_rude);
-
-int rcu_tasks_rude_lazy_ms = -1;
-module_param(rcu_tasks_rude_lazy_ms, int, 0444);
-
 static int __init rcu_spawn_tasks_rude_kthread(void)
 {
 	rcu_tasks_rude.gp_sleep = HZ / 10;
-	if (rcu_tasks_rude_lazy_ms >= 0)
-		rcu_tasks_rude.lazy_jiffies = msecs_to_jiffies(rcu_tasks_rude_lazy_ms);
 	rcu_spawn_tasks_kthread_generic(&rcu_tasks_rude);
 	return 0;
 }
@@ -1350,6 +1415,12 @@ void show_rcu_tasks_rude_gp_kthread(void)
 	show_rcu_tasks_generic_gp_kthread(&rcu_tasks_rude, "");
 }
 EXPORT_SYMBOL_GPL(show_rcu_tasks_rude_gp_kthread);
+
+void rcu_tasks_rude_torture_stats_print(char *tt, char *tf)
+{
+	rcu_tasks_torture_stats_print_generic(&rcu_tasks_rude, tt, tf, "");
+}
+EXPORT_SYMBOL_GPL(rcu_tasks_rude_torture_stats_print);
 #endif // !defined(CONFIG_TINY_RCU)
 
 struct task_struct *get_rcu_tasks_rude_gp_kthread(void)
@@ -1613,7 +1684,7 @@ static int trc_inspect_reader(struct task_struct *t, void *bhp_in)
 		// However, we cannot safely change its state.
 		n_heavy_reader_attempts++;
 		// Check for "running" idle tasks on offline CPUs.
-		if (!rcu_dynticks_zero_in_eqs(cpu, &t->trc_reader_nesting))
+		if (!rcu_watching_zero_in_eqs(cpu, &t->trc_reader_nesting))
 			return -EINVAL; // No quiescent state, do it the hard way.
 		n_heavy_reader_updates++;
 		nesting = 0;
@@ -2027,6 +2098,12 @@ void show_rcu_tasks_trace_gp_kthread(void)
 	show_rcu_tasks_generic_gp_kthread(&rcu_tasks_trace, buf);
 }
 EXPORT_SYMBOL_GPL(show_rcu_tasks_trace_gp_kthread);
+
+void rcu_tasks_trace_torture_stats_print(char *tt, char *tf)
+{
+	rcu_tasks_torture_stats_print_generic(&rcu_tasks_trace, tt, tf, "");
+}
+EXPORT_SYMBOL_GPL(rcu_tasks_trace_torture_stats_print);
 #endif // !defined(CONFIG_TINY_RCU)
 
 struct task_struct *get_rcu_tasks_trace_gp_kthread(void)
@@ -2070,17 +2147,13 @@ static struct rcu_tasks_test_desc tests[] = {
 		.notrun = IS_ENABLED(CONFIG_TASKS_RCU),
 	},
 	{
-		.name = "call_rcu_tasks_rude()",
-		/* If not defined, the test is skipped. */
-		.notrun = IS_ENABLED(CONFIG_TASKS_RUDE_RCU),
-	},
-	{
 		.name = "call_rcu_tasks_trace()",
 		/* If not defined, the test is skipped. */
 		.notrun = IS_ENABLED(CONFIG_TASKS_TRACE_RCU)
 	}
 };
 
+#if defined(CONFIG_TASKS_RCU) || defined(CONFIG_TASKS_TRACE_RCU)
 static void test_rcu_tasks_callback(struct rcu_head *rhp)
 {
 	struct rcu_tasks_test_desc *rttd =
@@ -2090,6 +2163,7 @@ static void test_rcu_tasks_callback(struct rcu_head *rhp)
 
 	rttd->notrun = false;
 }
+#endif // #if defined(CONFIG_TASKS_RCU) || defined(CONFIG_TASKS_TRACE_RCU)
 
 static void rcu_tasks_initiate_self_tests(void)
 {
@@ -2102,16 +2176,14 @@ static void rcu_tasks_initiate_self_tests(void)
 
 #ifdef CONFIG_TASKS_RUDE_RCU
 	pr_info("Running RCU Tasks Rude wait API self tests\n");
-	tests[1].runstart = jiffies;
 	synchronize_rcu_tasks_rude();
-	call_rcu_tasks_rude(&tests[1].rh, test_rcu_tasks_callback);
 #endif
 
 #ifdef CONFIG_TASKS_TRACE_RCU
 	pr_info("Running RCU Tasks Trace wait API self tests\n");
-	tests[2].runstart = jiffies;
+	tests[1].runstart = jiffies;
 	synchronize_rcu_tasks_trace();
-	call_rcu_tasks_trace(&tests[2].rh, test_rcu_tasks_callback);
+	call_rcu_tasks_trace(&tests[1].rh, test_rcu_tasks_callback);
 #endif
 }