Merge branches 'doc.2016.08.22c', 'exp.2016.08.22c', 'fixes.2016.09.14a',...

Merge branches 'doc.2016.08.22c', 'exp.2016.08.22c', 'fixes.2016.09.14a', 'hotplug.2016.08.22c' and 'torture.2016.08.22c' into HEAD

doc.2016.08.22c: Documentation updates
exp.2016.08.22c: Expedited grace-period updates
fixes.2016.09.14a: Miscellaneous fixes
hotplug.2016.08.22c: CPU-hotplug changes
torture.2016.08.22c: Torture-test changes

include/linux/list.h

@@ -381,8 +381,11 @@ static inline void list_splice_tail_init(struct list_head *list,
  *
  * Note that if the list is empty, it returns NULL.
  */
-#define list_first_entry_or_null(ptr, type, member) \
-	(!list_empty(ptr) ? list_first_entry(ptr, type, member) : NULL)
+#define list_first_entry_or_null(ptr, type, member) ({ \
+	struct list_head *head__ = (ptr); \
+	struct list_head *pos__ = READ_ONCE(head__->next); \
+	pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
+})
 
 /**
  * list_next_entry - get the next element in list

include/linux/rcupdate.h

@@ -334,6 +334,7 @@ void rcu_sched_qs(void);
 void rcu_bh_qs(void);
 void rcu_check_callbacks(int user);
 void rcu_report_dead(unsigned int cpu);
+void rcu_cpu_starting(unsigned int cpu);
 
 #ifndef CONFIG_TINY_RCU
 void rcu_end_inkernel_boot(void);

include/linux/torture.h

@@ -43,7 +43,7 @@
 
 #define TORTURE_FLAG "-torture:"
 #define TOROUT_STRING(s) \
-	pr_alert("%s" TORTURE_FLAG s "\n", torture_type)
+	pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s)
 #define VERBOSE_TOROUT_STRING(s) \
 	do { if (verbose) pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s); } while (0)
 #define VERBOSE_TOROUT_ERRSTRING(s) \

kernel/cpu.c

@@ -889,6 +889,7 @@ void notify_cpu_starting(unsigned int cpu)
 	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
 	enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);
 
+	rcu_cpu_starting(cpu);	/* Enables RCU usage on this CPU. */
 	while (st->state < target) {
 		struct cpuhp_step *step;
 

kernel/rcu/rcuperf.c

@@ -52,7 +52,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
 
 #define PERF_FLAG "-perf:"
 #define PERFOUT_STRING(s) \
-	pr_alert("%s" PERF_FLAG s "\n", perf_type)
+	pr_alert("%s" PERF_FLAG " %s\n", perf_type, s)
 #define VERBOSE_PERFOUT_STRING(s) \
 	do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
 #define VERBOSE_PERFOUT_ERRSTRING(s) \
@@ -400,9 +400,8 @@ rcu_perf_writer(void *arg)
 			sp.sched_priority = 0;
 			sched_setscheduler_nocheck(current,
 						   SCHED_NORMAL, &sp);
-			pr_alert("%s" PERF_FLAG
-				 "rcu_perf_writer %ld has %d measurements\n",
-				 perf_type, me, MIN_MEAS);
+			pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
+				 perf_type, PERF_FLAG, me, MIN_MEAS);
 			if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
 			    nrealwriters) {
 				schedule_timeout_interruptible(10);

kernel/rcu/rcutorture.c

@@ -1238,6 +1238,7 @@ rcu_torture_stats_print(void)
 	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 	static unsigned long rtcv_snap = ULONG_MAX;
+	struct task_struct *wtp;
 
 	for_each_possible_cpu(cpu) {
 		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
@@ -1258,8 +1259,9 @@ rcu_torture_stats_print(void)
 		atomic_read(&n_rcu_torture_alloc),
 		atomic_read(&n_rcu_torture_alloc_fail),
 		atomic_read(&n_rcu_torture_free));
-	pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
+	pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
 		atomic_read(&n_rcu_torture_mberror),
+		n_rcu_torture_barrier_error,
 		n_rcu_torture_boost_ktrerror,
 		n_rcu_torture_boost_rterror);
 	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
@@ -1312,10 +1314,12 @@ rcu_torture_stats_print(void)
 
 		rcutorture_get_gp_data(cur_ops->ttype,
 				       &flags, &gpnum, &completed);
-		pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
+		wtp = READ_ONCE(writer_task);
+		pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n",
 			 rcu_torture_writer_state_getname(),
 			 rcu_torture_writer_state,
-			 gpnum, completed, flags);
+			 gpnum, completed, flags,
+			 wtp == NULL ? ~0UL : wtp->state);
 		show_rcu_gp_kthreads();
 		rcu_ftrace_dump(DUMP_ALL);
 	}
@@ -1362,12 +1366,12 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
 		 onoff_interval, onoff_holdoff);
 }
 
-static void rcutorture_booster_cleanup(int cpu)
+static int rcutorture_booster_cleanup(unsigned int cpu)
 {
 	struct task_struct *t;
 
 	if (boost_tasks[cpu] == NULL)
-		return;
+		return 0;
 	mutex_lock(&boost_mutex);
 	t = boost_tasks[cpu];
 	boost_tasks[cpu] = NULL;
@@ -1375,9 +1379,10 @@ static void rcutorture_booster_cleanup(int cpu)
 
 	/* This must be outside of the mutex, otherwise deadlock! */
 	torture_stop_kthread(rcu_torture_boost, t);
+	return 0;
 }
 
-static int rcutorture_booster_init(int cpu)
+static int rcutorture_booster_init(unsigned int cpu)
 {
 	int retval;
 
@@ -1577,28 +1582,7 @@ static void rcu_torture_barrier_cleanup(void)
 	}
 }
 
-static int rcutorture_cpu_notify(struct notifier_block *self,
-				 unsigned long action, void *hcpu)
-{
-	long cpu = (long)hcpu;
-
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_ONLINE:
-	case CPU_DOWN_FAILED:
-		(void)rcutorture_booster_init(cpu);
-		break;
-	case CPU_DOWN_PREPARE:
-		rcutorture_booster_cleanup(cpu);
-		break;
-	default:
-		break;
-	}
-	return NOTIFY_OK;
-}
-
-static struct notifier_block rcutorture_cpu_nb = {
-	.notifier_call = rcutorture_cpu_notify,
-};
+static enum cpuhp_state rcutor_hp;
 
 static void
 rcu_torture_cleanup(void)
@@ -1638,11 +1622,8 @@ rcu_torture_cleanup(void)
 	for (i = 0; i < ncbflooders; i++)
 		torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
 	if ((test_boost == 1 && cur_ops->can_boost) ||
-	    test_boost == 2) {
-		unregister_cpu_notifier(&rcutorture_cpu_nb);
-		for_each_possible_cpu(i)
-			rcutorture_booster_cleanup(i);
-	}
+	    test_boost == 2)
+		cpuhp_remove_state(rcutor_hp);
 
 	/*
 	 * Wait for all RCU callbacks to fire, then do flavor-specific
@@ -1869,14 +1850,13 @@ rcu_torture_init(void)
 	    test_boost == 2) {
 
 		boost_starttime = jiffies + test_boost_interval * HZ;
-		register_cpu_notifier(&rcutorture_cpu_nb);
-		for_each_possible_cpu(i) {
-			if (cpu_is_offline(i))
-				continue;  /* Heuristic: CPU can go offline. */
-			firsterr = rcutorture_booster_init(i);
-			if (firsterr)
+
+		firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
+					     rcutorture_booster_init,
+					     rcutorture_booster_cleanup);
+		if (firsterr < 0)
 			goto unwind;
-		}
+		rcutor_hp = firsterr;
 	}
 	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
 	if (firsterr)

kernel/rcu/tree.c

@@ -41,7 +41,6 @@
 #include <linux/export.h>
 #include <linux/completion.h>
 #include <linux/moduleparam.h>
-#include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
@@ -60,7 +59,6 @@
 #include "tree.h"
 #include "rcu.h"
 
-MODULE_ALIAS("rcutree");
 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
 #endif
@@ -1848,6 +1846,7 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
 			      struct rcu_data *rdp)
 {
 	bool ret;
+	bool need_gp;
 
 	/* Handle the ends of any preceding grace periods first. */
 	if (rdp->completed == rnp->completed &&
@@ -1874,9 +1873,10 @@ static bool __note_gp_changes(struct rcu_state *rsp, struct rcu_node *rnp,
 		 */
 		rdp->gpnum = rnp->gpnum;
 		trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpustart"));
-		rdp->cpu_no_qs.b.norm = true;
+		need_gp = !!(rnp->qsmask & rdp->grpmask);
+		rdp->cpu_no_qs.b.norm = need_gp;
 		rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
-		rdp->core_needs_qs = !!(rnp->qsmask & rdp->grpmask);
+		rdp->core_needs_qs = need_gp;
 		zero_cpu_stall_ticks(rdp);
 		WRITE_ONCE(rdp->gpwrap, false);
 	}
@@ -2344,7 +2344,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
 	WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
 	WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
 	raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);
-	swake_up(&rsp->gp_wq);  /* Memory barrier implied by swake_up() path. */
+	rcu_gp_kthread_wake(rsp);
 }
 
 /*
@@ -2970,7 +2970,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
 	}
 	WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);
 	raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);
-	swake_up(&rsp->gp_wq); /* Memory barrier implied by swake_up() path. */
+	rcu_gp_kthread_wake(rsp);
 }
 
 /*
@@ -3792,8 +3792,6 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
 	rnp = rdp->mynode;
 	mask = rdp->grpmask;
 	raw_spin_lock_rcu_node(rnp);		/* irqs already disabled. */
-	rnp->qsmaskinitnext |= mask;
-	rnp->expmaskinitnext |= mask;
 	if (!rdp->beenonline)
 		WRITE_ONCE(rsp->ncpus, READ_ONCE(rsp->ncpus) + 1);
 	rdp->beenonline = true;	 /* We have now been online. */
@@ -3860,6 +3858,32 @@ int rcutree_dead_cpu(unsigned int cpu)
 	return 0;
 }
 
+/*
+ * Mark the specified CPU as being online so that subsequent grace periods
+ * (both expedited and normal) will wait on it.  Note that this means that
+ * incoming CPUs are not allowed to use RCU read-side critical sections
+ * until this function is called.  Failing to observe this restriction
+ * will result in lockdep splats.
+ */
+void rcu_cpu_starting(unsigned int cpu)
+{
+	unsigned long flags;
+	unsigned long mask;
+	struct rcu_data *rdp;
+	struct rcu_node *rnp;
+	struct rcu_state *rsp;
+
+	for_each_rcu_flavor(rsp) {
+		rdp = this_cpu_ptr(rsp->rda);
+		rnp = rdp->mynode;
+		mask = rdp->grpmask;
+		raw_spin_lock_irqsave_rcu_node(rnp, flags);
+		rnp->qsmaskinitnext |= mask;
+		rnp->expmaskinitnext |= mask;
+		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
+	}
+}
+
 #ifdef CONFIG_HOTPLUG_CPU
 /*
  * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
@@ -4209,8 +4233,10 @@ void __init rcu_init(void)
 	 * or the scheduler are operational.
 	 */
 	pm_notifier(rcu_pm_notify, 0);
-	for_each_online_cpu(cpu)
+	for_each_online_cpu(cpu) {
 		rcutree_prepare_cpu(cpu);
+		rcu_cpu_starting(cpu);
+	}
 }
 
 #include "tree_exp.h"

kernel/rcu/tree.h

@@ -400,6 +400,7 @@ struct rcu_data {
 #ifdef CONFIG_RCU_FAST_NO_HZ
 	struct rcu_head oom_head;
 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
+	atomic_long_t exp_workdone0;	/* # done by workqueue. */
 	atomic_long_t exp_workdone1;	/* # done by others #1. */
 	atomic_long_t exp_workdone2;	/* # done by others #2. */
 	atomic_long_t exp_workdone3;	/* # done by others #3. */

kernel/rcu/tree_exp.h

@@ -359,7 +359,8 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
 			struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
 
 			if (raw_smp_processor_id() == cpu ||
-			    !(atomic_add_return(0, &rdtp->dynticks) & 0x1))
+			    !(atomic_add_return(0, &rdtp->dynticks) & 0x1) ||
+			    !(rnp->qsmaskinitnext & rdp->grpmask))
 				mask_ofl_test |= rdp->grpmask;
 		}
 		mask_ofl_ipi = rnp->expmask & ~mask_ofl_test;
@@ -384,17 +385,16 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
 				mask_ofl_ipi &= ~mask;
 				continue;
 			}
-			/* Failed, raced with offline. */
+			/* Failed, raced with CPU hotplug operation. */
 			raw_spin_lock_irqsave_rcu_node(rnp, flags);
-			if (cpu_online(cpu) &&
+			if ((rnp->qsmaskinitnext & mask) &&
 			    (rnp->expmask & mask)) {
+				/* Online, so delay for a bit and try again. */
 				raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 				schedule_timeout_uninterruptible(1);
-				if (cpu_online(cpu) &&
-				    (rnp->expmask & mask))
 				goto retry_ipi;
-				raw_spin_lock_irqsave_rcu_node(rnp, flags);
 			}
+			/* CPU really is offline, so we can ignore it. */
 			if (!(rnp->expmask & mask))
 				mask_ofl_ipi &= ~mask;
 			raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
@@ -427,12 +427,10 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
 				jiffies_stall);
 		if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root))
 			return;
-		if (ret < 0) {
-			/* Hit a signal, disable CPU stall warnings. */
-			swait_event(rsp->expedited_wq,
-				   sync_rcu_preempt_exp_done(rnp_root));
-			return;
-		}
+		WARN_ON(ret < 0);  /* workqueues should not be signaled. */
+		if (rcu_cpu_stall_suppress)
+			continue;
+		panic_on_rcu_stall();
 		pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
 		       rsp->name);
 		ndetected = 0;
@@ -500,7 +498,6 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
 	 * next GP, to proceed.
 	 */
 	mutex_lock(&rsp->exp_wake_mutex);
-	mutex_unlock(&rsp->exp_mutex);
 
 	rcu_for_each_node_breadth_first(rsp, rnp) {
 		if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) {
@@ -516,6 +513,70 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
 	mutex_unlock(&rsp->exp_wake_mutex);
 }
 
+/* Let the workqueue handler know what it is supposed to do. */
+struct rcu_exp_work {
+	smp_call_func_t rew_func;
+	struct rcu_state *rew_rsp;
+	unsigned long rew_s;
+	struct work_struct rew_work;
+};
+
+/*
+ * Work-queue handler to drive an expedited grace period forward.
+ */
+static void wait_rcu_exp_gp(struct work_struct *wp)
+{
+	struct rcu_exp_work *rewp;
+
+	/* Initialize the rcu_node tree in preparation for the wait. */
+	rewp = container_of(wp, struct rcu_exp_work, rew_work);
+	sync_rcu_exp_select_cpus(rewp->rew_rsp, rewp->rew_func);
+
+	/* Wait and clean up, including waking everyone. */
+	rcu_exp_wait_wake(rewp->rew_rsp, rewp->rew_s);
+}
+
+/*
+ * Given an rcu_state pointer and a smp_call_function() handler, kick
+ * off the specified flavor of expedited grace period.
+ */
+static void _synchronize_rcu_expedited(struct rcu_state *rsp,
+				       smp_call_func_t func)
+{
+	struct rcu_data *rdp;
+	struct rcu_exp_work rew;
+	struct rcu_node *rnp;
+	unsigned long s;
+
+	/* If expedited grace periods are prohibited, fall back to normal. */
+	if (rcu_gp_is_normal()) {
+		wait_rcu_gp(rsp->call);
+		return;
+	}
+
+	/* Take a snapshot of the sequence number.  */
+	s = rcu_exp_gp_seq_snap(rsp);
+	if (exp_funnel_lock(rsp, s))
+		return;  /* Someone else did our work for us. */
+
+	/* Marshall arguments and schedule the expedited grace period. */
+	rew.rew_func = func;
+	rew.rew_rsp = rsp;
+	rew.rew_s = s;
+	INIT_WORK_ONSTACK(&rew.rew_work, wait_rcu_exp_gp);
+	schedule_work(&rew.rew_work);
+
+	/* Wait for expedited grace period to complete. */
+	rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
+	rnp = rcu_get_root(rsp);
+	wait_event(rnp->exp_wq[(s >> 1) & 0x3],
+		   sync_exp_work_done(rsp,
+				      &rdp->exp_workdone0, s));
+
+	/* Let the next expedited grace period start. */
+	mutex_unlock(&rsp->exp_mutex);
+}
+
 /**
  * synchronize_sched_expedited - Brute-force RCU-sched grace period
  *
@@ -534,29 +595,13 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
  */
 void synchronize_sched_expedited(void)
 {
-	unsigned long s;
 	struct rcu_state *rsp = &rcu_sched_state;
 
 	/* If only one CPU, this is automatically a grace period. */
 	if (rcu_blocking_is_gp())
 		return;
 
-	/* If expedited grace periods are prohibited, fall back to normal. */
-	if (rcu_gp_is_normal()) {
-		wait_rcu_gp(call_rcu_sched);
-		return;
-	}
-
-	/* Take a snapshot of the sequence number.  */
-	s = rcu_exp_gp_seq_snap(rsp);
-	if (exp_funnel_lock(rsp, s))
-		return;  /* Someone else did our work for us. */
-
-	/* Initialize the rcu_node tree in preparation for the wait. */
-	sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
-
-	/* Wait and clean up, including waking everyone. */
-	rcu_exp_wait_wake(rsp, s);
+	_synchronize_rcu_expedited(rsp, sync_sched_exp_handler);
 }
 EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
 
@@ -620,23 +665,8 @@ static void sync_rcu_exp_handler(void *info)
 void synchronize_rcu_expedited(void)
 {
 	struct rcu_state *rsp = rcu_state_p;
-	unsigned long s;
-
-	/* If expedited grace periods are prohibited, fall back to normal. */
-	if (rcu_gp_is_normal()) {
-		wait_rcu_gp(call_rcu);
-		return;
-	}
-
-	s = rcu_exp_gp_seq_snap(rsp);
-	if (exp_funnel_lock(rsp, s))
-		return;  /* Someone else did our work for us. */
-
-	/* Initialize the rcu_node tree in preparation for the wait. */
-	sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
 
-	/* Wait for ->blkd_tasks lists to drain, then wake everyone up. */
-	rcu_exp_wait_wake(rsp, s);
+	_synchronize_rcu_expedited(rsp, sync_rcu_exp_handler);
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
 

kernel/rcu/tree_plugin.h

@@ -2173,6 +2173,7 @@ static int rcu_nocb_kthread(void *arg)
 				cl++;
 			c++;
 			local_bh_enable();
+			cond_resched_rcu_qs();
 			list = next;
 		}
 		trace_rcu_batch_end(rdp->rsp->name, c, !!list, 0, 0, 1);

kernel/rcu/tree_trace.c

@@ -185,16 +185,17 @@ static int show_rcuexp(struct seq_file *m, void *v)
 	int cpu;
 	struct rcu_state *rsp = (struct rcu_state *)m->private;
 	struct rcu_data *rdp;
-	unsigned long s1 = 0, s2 = 0, s3 = 0;
+	unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0;
 
 	for_each_possible_cpu(cpu) {
 		rdp = per_cpu_ptr(rsp->rda, cpu);
+		s0 += atomic_long_read(&rdp->exp_workdone0);
 		s1 += atomic_long_read(&rdp->exp_workdone1);
 		s2 += atomic_long_read(&rdp->exp_workdone2);
 		s3 += atomic_long_read(&rdp->exp_workdone3);
 	}
-	seq_printf(m, "s=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
-		   rsp->expedited_sequence, s1, s2, s3,
+	seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n",
+		   rsp->expedited_sequence, s0, s1, s2, s3,
 		   atomic_long_read(&rsp->expedited_normal),
 		   atomic_read(&rsp->expedited_need_qs),
 		   rsp->expedited_sequence / 2);

kernel/rcu/update.c

@@ -46,7 +46,7 @@
 #include <linux/export.h>
 #include <linux/hardirq.h>
 #include <linux/delay.h>
-#include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/kthread.h>
 #include <linux/tick.h>
 
@@ -54,7 +54,6 @@
 
 #include "rcu.h"
 
-MODULE_ALIAS("rcupdate");
 #ifdef MODULE_PARAM_PREFIX
 #undef MODULE_PARAM_PREFIX
 #endif

kernel/sched/core.c

@@ -580,6 +580,8 @@ static bool wake_up_full_nohz_cpu(int cpu)
 	 * If needed we can still optimize that later with an
 	 * empty IRQ.
 	 */
+	if (cpu_is_offline(cpu))
+		return true;  /* Don't try to wake offline CPUs. */
 	if (tick_nohz_full_cpu(cpu)) {
 		if (cpu != smp_processor_id() ||
 		    tick_nohz_tick_stopped())
@@ -590,6 +592,11 @@ static bool wake_up_full_nohz_cpu(int cpu)
 	return false;
 }
 
+/*
+ * Wake up the specified CPU.  If the CPU is going offline, it is the
+ * caller's responsibility to deal with the lost wakeup, for example,
+ * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
+ */
 void wake_up_nohz_cpu(int cpu)
 {
 	if (!wake_up_full_nohz_cpu(cpu))

kernel/torture.c

@@ -43,6 +43,7 @@
 #include <linux/stat.h>
 #include <linux/slab.h>
 #include <linux/trace_clock.h>
+#include <linux/ktime.h>
 #include <asm/byteorder.h>
 #include <linux/torture.h>
 
@@ -446,9 +447,8 @@ EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
  * Variables for auto-shutdown.  This allows "lights out" torture runs
  * to be fully scripted.
  */
-static int shutdown_secs;		/* desired test duration in seconds. */
 static struct task_struct *shutdown_task;
-static unsigned long shutdown_time;	/* jiffies to system shutdown. */
+static ktime_t shutdown_time;		/* time to system shutdown. */
 static void (*torture_shutdown_hook)(void);
 
 /*
@@ -471,20 +471,20 @@ EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
  */
 static int torture_shutdown(void *arg)
 {
-	long delta;
-	unsigned long jiffies_snap;
+	ktime_t ktime_snap;
 
 	VERBOSE_TOROUT_STRING("torture_shutdown task started");
-	jiffies_snap = jiffies;
-	while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
+	ktime_snap = ktime_get();
+	while (ktime_before(ktime_snap, shutdown_time) &&
 	       !torture_must_stop()) {
-		delta = shutdown_time - jiffies_snap;
 		if (verbose)
 			pr_alert("%s" TORTURE_FLAG
-				 "torture_shutdown task: %lu jiffies remaining\n",
-				 torture_type, delta);
-		schedule_timeout_interruptible(delta);
-		jiffies_snap = jiffies;
+				 "torture_shutdown task: %llu ms remaining\n",
+				 torture_type,
+				 ktime_ms_delta(shutdown_time, ktime_snap));
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
+		ktime_snap = ktime_get();
 	}
 	if (torture_must_stop()) {
 		torture_kthread_stopping("torture_shutdown");
@@ -511,10 +511,9 @@ int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 {
 	int ret = 0;
 
-	shutdown_secs = ssecs;
 	torture_shutdown_hook = cleanup;
-	if (shutdown_secs > 0) {
-		shutdown_time = jiffies + shutdown_secs * HZ;
+	if (ssecs > 0) {
+		shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
 		ret = torture_create_kthread(torture_shutdown, NULL,
 					     shutdown_task);
 	}