X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Frcutree.c;h=d4437345706f8a539eee6dba201662fd791978ef;hb=31f46717997a83bdf6db0dd04810c0a329eb3148;hp=41688ff60e0729b8486961b176b18240284e547f;hpb=07079d5357a4d53c2b13126c4a38fb40e6e04966;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 41688ff..d443734 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -54,8 +54,8 @@
 
 static struct lock_class_key rcu_node_class[NUM_RCU_LVLS];
 
-#define RCU_STATE_INITIALIZER(name) { \
-	.level = { &name.node[0] }, \
+#define RCU_STATE_INITIALIZER(structname) { \
+	.level = { &structname.node[0] }, \
 	.levelcnt = { \
 		NUM_RCU_LVL_0,  /* root of hierarchy. */ \
 		NUM_RCU_LVL_1, \
@@ -66,13 +66,14 @@ static struct lock_class_key rcu_node_class[NUM_RCU_LVLS];
 	.signaled = RCU_GP_IDLE, \
 	.gpnum = -300, \
 	.completed = -300, \
-	.onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \
+	.onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \
 	.orphan_cbs_list = NULL, \
-	.orphan_cbs_tail = &name.orphan_cbs_list, \
+	.orphan_cbs_tail = &structname.orphan_cbs_list, \
 	.orphan_qlen = 0, \
-	.fqslock = __SPIN_LOCK_UNLOCKED(&name.fqslock), \
+	.fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \
 	.n_force_qs = 0, \
 	.n_force_qs_ngp = 0, \
+	.name = #structname, \
 }
 
 struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state);
@@ -81,8 +82,8 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);
 struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
 DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
 
-static int rcu_scheduler_active __read_mostly;
-
+int rcu_scheduler_active __read_mostly;
+EXPORT_SYMBOL_GPL(rcu_scheduler_active);
 
 /*
  * Return true if an RCU grace period is in progress.  The ACCESS_ONCE()s
@@ -101,25 +102,32 @@ static int rcu_gp_in_progress(struct rcu_state *rsp)
  */
 void rcu_sched_qs(int cpu)
 {
-	struct rcu_data *rdp;
+	struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
 
-	rdp = &per_cpu(rcu_sched_data, cpu);
 	rdp->passed_quiesc_completed = rdp->gpnum - 1;
 	barrier();
 	rdp->passed_quiesc = 1;
-	rcu_preempt_note_context_switch(cpu);
 }
 
 void rcu_bh_qs(int cpu)
 {
-	struct rcu_data *rdp;
+	struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
 
-	rdp = &per_cpu(rcu_bh_data, cpu);
 	rdp->passed_quiesc_completed = rdp->gpnum - 1;
 	barrier();
 	rdp->passed_quiesc = 1;
 }
 
+/*
+ * Note a context switch.  This is a quiescent state for RCU-sched,
+ * and requires special handling for preemptible RCU.
+ */
+void rcu_note_context_switch(int cpu)
+{
+	rcu_sched_qs(cpu);
+	rcu_preempt_note_context_switch(cpu);
+}
+
 #ifdef CONFIG_NO_HZ
 DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
 	.dynticks_nesting = 1,
@@ -157,6 +165,24 @@ long rcu_batches_completed_bh(void)
 EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
 
 /*
+ * Force a quiescent state for RCU BH.
+ */
+void rcu_bh_force_quiescent_state(void)
+{
+	force_quiescent_state(&rcu_bh_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
+
+/*
+ * Force a quiescent state for RCU-sched.
+ */
+void rcu_sched_force_quiescent_state(void)
+{
+	force_quiescent_state(&rcu_sched_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
+
+/*
  * Does the CPU have callbacks ready to be invoked?
  */
 static int
@@ -424,6 +450,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 
+int rcu_cpu_stall_panicking __read_mostly;
+
 static void record_gp_stall_check_time(struct rcu_state *rsp)
 {
 	rsp->gp_start = jiffies;
@@ -439,10 +467,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
 
 	/* Only let one CPU complain about others per time interval. */
 
-	spin_lock_irqsave(&rnp->lock, flags);
+	raw_spin_lock_irqsave(&rnp->lock, flags);
 	delta = jiffies - rsp->jiffies_stall;
 	if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		return;
 	}
 	rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
@@ -452,23 +480,30 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
 	 * due to CPU offlining.
 	 */
 	rcu_print_task_stall(rnp);
-	spin_unlock_irqrestore(&rnp->lock, flags);
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
 	/* OK, time to rat on our buddy... */
 
-	printk(KERN_ERR "INFO: RCU detected CPU stalls:");
+	printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {",
+	       rsp->name);
 	rcu_for_each_leaf_node(rsp, rnp) {
+		raw_spin_lock_irqsave(&rnp->lock, flags);
 		rcu_print_task_stall(rnp);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		if (rnp->qsmask == 0)
 			continue;
 		for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
 			if (rnp->qsmask & (1UL << cpu))
 				printk(" %d", rnp->grplo + cpu);
 	}
-	printk(" (detected by %d, t=%ld jiffies)\n",
+	printk("} (detected by %d, t=%ld jiffies)\n",
 	       smp_processor_id(), (long)(jiffies - rsp->gp_start));
 	trigger_all_cpu_backtrace();
 
+	/* If so configured, complain about tasks blocking the grace period. */
+
+	rcu_print_detail_task_stall(rsp);
+
 	force_quiescent_state(rsp, 0);  /* Kick them all. */
 }
 
@@ -477,15 +512,15 @@ static void print_cpu_stall(struct rcu_state *rsp)
 	unsigned long flags;
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
-	printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n",
-			smp_processor_id(), jiffies - rsp->gp_start);
+	printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n",
+	       rsp->name, smp_processor_id(), jiffies - rsp->gp_start);
 	trigger_all_cpu_backtrace();
 
-	spin_lock_irqsave(&rnp->lock, flags);
-	if ((long)(jiffies - rsp->jiffies_stall) >= 0)
+	raw_spin_lock_irqsave(&rnp->lock, flags);
+	if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall))
 		rsp->jiffies_stall =
 			jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
-	spin_unlock_irqrestore(&rnp->lock, flags);
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
 	set_need_resched();  /* kick ourselves to get things going. */
 }
@@ -495,6 +530,8 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 	long delta;
 	struct rcu_node *rnp;
 
+	if (rcu_cpu_stall_panicking)
+		return;
 	delta = jiffies - rsp->jiffies_stall;
 	rnp = rdp->mynode;
 	if ((rnp->qsmask & rdp->grpmask) && delta >= 0) {
@@ -509,6 +546,21 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 	}
 }
 
+static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
+{
+	rcu_cpu_stall_panicking = 1;
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rcu_panic_block = {
+	.notifier_call = rcu_panic,
+};
+
+static void __init check_cpu_stall_init(void)
+{
+	atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
+}
+
 #else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
 static void record_gp_stall_check_time(struct rcu_state *rsp)
@@ -519,6 +571,10 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 {
 }
 
+static void __init check_cpu_stall_init(void)
+{
+}
+
 #endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
 /*
@@ -545,12 +601,12 @@ static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp)
 	local_irq_save(flags);
 	rnp = rdp->mynode;
 	if (rdp->gpnum == ACCESS_ONCE(rnp->gpnum) || /* outside lock. */
-	    !spin_trylock(&rnp->lock)) { /* irqs already off, retry later. */
+	    !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
 		local_irq_restore(flags);
 		return;
 	}
 	__note_new_gpnum(rsp, rnp, rdp);
-	spin_unlock_irqrestore(&rnp->lock, flags);
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 }
 
 /*
@@ -609,12 +665,12 @@ rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
 	local_irq_save(flags);
 	rnp = rdp->mynode;
 	if (rdp->completed == ACCESS_ONCE(rnp->completed) || /* outside lock. */
-	    !spin_trylock(&rnp->lock)) { /* irqs already off, retry later. */
+	    !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
 		local_irq_restore(flags);
 		return;
 	}
 	__rcu_process_gp_end(rsp, rnp, rdp);
-	spin_unlock_irqrestore(&rnp->lock, flags);
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 }
 
 /*
@@ -660,11 +716,13 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) {
+		if (cpu_needs_another_gp(rsp, rdp))
+			rsp->fqs_need_gp = 1;
 		if (rnp->completed == rsp->completed) {
-			spin_unlock_irqrestore(&rnp->lock, flags);
+			raw_spin_unlock_irqrestore(&rnp->lock, flags);
 			return;
 		}
-		spin_unlock(&rnp->lock);	 /* irqs remain disabled. */
+		raw_spin_unlock(&rnp->lock);	 /* irqs remain disabled. */
 
 		/*
 		 * Propagate new ->completed value to rcu_node structures
@@ -672,9 +730,9 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 		 * of the next grace period to process their callbacks.
 		 */
 		rcu_for_each_node_breadth_first(rsp, rnp) {
-			spin_lock(&rnp->lock);	 /* irqs already disabled. */
+			raw_spin_lock(&rnp->lock); /* irqs already disabled. */
 			rnp->completed = rsp->completed;
-			spin_unlock(&rnp->lock); /* irqs remain disabled. */
+			raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
 		}
 		local_irq_restore(flags);
 		return;
@@ -695,15 +753,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 		rnp->completed = rsp->completed;
 		rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state OK. */
 		rcu_start_gp_per_cpu(rsp, rnp, rdp);
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		return;
 	}
 
-	spin_unlock(&rnp->lock);  /* leave irqs disabled. */
+	raw_spin_unlock(&rnp->lock);  /* leave irqs disabled. */
 
 
 	/* Exclude any concurrent CPU-hotplug operations. */
-	spin_lock(&rsp->onofflock);  /* irqs already disabled. */
+	raw_spin_lock(&rsp->onofflock);  /* irqs already disabled. */
 
 	/*
 	 * Set the quiescent-state-needed bits in all the rcu_node
@@ -723,21 +781,21 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 	 * irqs disabled.
 	 */
 	rcu_for_each_node_breadth_first(rsp, rnp) {
-		spin_lock(&rnp->lock);		/* irqs already disabled. */
+		raw_spin_lock(&rnp->lock);	/* irqs already disabled. */
 		rcu_preempt_check_blocked_tasks(rnp);
 		rnp->qsmask = rnp->qsmaskinit;
 		rnp->gpnum = rsp->gpnum;
 		rnp->completed = rsp->completed;
 		if (rnp == rdp->mynode)
 			rcu_start_gp_per_cpu(rsp, rnp, rdp);
-		spin_unlock(&rnp->lock);	/* irqs remain disabled. */
+		raw_spin_unlock(&rnp->lock);	/* irqs remain disabled. */
 	}
 
 	rnp = rcu_get_root(rsp);
-	spin_lock(&rnp->lock);			/* irqs already disabled. */
+	raw_spin_lock(&rnp->lock);		/* irqs already disabled. */
 	rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */
-	spin_unlock(&rnp->lock);		/* irqs remain disabled. */
-	spin_unlock_irqrestore(&rsp->onofflock, flags);
+	raw_spin_unlock(&rnp->lock);		/* irqs remain disabled. */
+	raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
 }
 
 /*
@@ -776,14 +834,14 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
 		if (!(rnp->qsmask & mask)) {
 
 			/* Our bit has already been cleared, so done. */
-			spin_unlock_irqrestore(&rnp->lock, flags);
+			raw_spin_unlock_irqrestore(&rnp->lock, flags);
 			return;
 		}
 		rnp->qsmask &= ~mask;
 		if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) {
 
 			/* Other bits still set at this level, so done. */
-			spin_unlock_irqrestore(&rnp->lock, flags);
+			raw_spin_unlock_irqrestore(&rnp->lock, flags);
 			return;
 		}
 		mask = rnp->grpmask;
@@ -793,10 +851,10 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
 
 			break;
 		}
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		rnp_c = rnp;
 		rnp = rnp->parent;
-		spin_lock_irqsave(&rnp->lock, flags);
+		raw_spin_lock_irqsave(&rnp->lock, flags);
 		WARN_ON_ONCE(rnp_c->qsmask);
 	}
 
@@ -825,7 +883,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long las
 	struct rcu_node *rnp;
 
 	rnp = rdp->mynode;
-	spin_lock_irqsave(&rnp->lock, flags);
+	raw_spin_lock_irqsave(&rnp->lock, flags);
 	if (lastcomp != rnp->completed) {
 
 		/*
@@ -837,12 +895,12 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long las
 		 * race occurred.
 		 */
 		rdp->passed_quiesc = 0;	/* try again later! */
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 		return;
 	}
 	mask = rdp->grpmask;
 	if ((rnp->qsmask & mask) == 0) {
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 	} else {
 		rdp->qs_pending = 0;
 
@@ -906,7 +964,7 @@ static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp)
 
 	if (rdp->nxtlist == NULL)
 		return;  /* irqs disabled, so comparison is stable. */
-	spin_lock(&rsp->onofflock);  /* irqs already disabled. */
+	raw_spin_lock(&rsp->onofflock);  /* irqs already disabled. */
 	*rsp->orphan_cbs_tail = rdp->nxtlist;
 	rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL];
 	rdp->nxtlist = NULL;
@@ -914,7 +972,7 @@ static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp)
 		rdp->nxttail[i] = &rdp->nxtlist;
 	rsp->orphan_qlen += rdp->qlen;
 	rdp->qlen = 0;
-	spin_unlock(&rsp->onofflock);  /* irqs remain disabled. */
+	raw_spin_unlock(&rsp->onofflock);  /* irqs remain disabled. */
 }
 
 /*
@@ -925,10 +983,10 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
 	unsigned long flags;
 	struct rcu_data *rdp;
 
-	spin_lock_irqsave(&rsp->onofflock, flags);
+	raw_spin_lock_irqsave(&rsp->onofflock, flags);
 	rdp = rsp->rda[smp_processor_id()];
 	if (rsp->orphan_cbs_list == NULL) {
-		spin_unlock_irqrestore(&rsp->onofflock, flags);
+		raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
 		return;
 	}
 	*rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list;
@@ -937,7 +995,7 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
 	rsp->orphan_cbs_list = NULL;
 	rsp->orphan_cbs_tail = &rsp->orphan_cbs_list;
 	rsp->orphan_qlen = 0;
-	spin_unlock_irqrestore(&rsp->onofflock, flags);
+	raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
 }
 
 /*
@@ -953,23 +1011,23 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
 	struct rcu_node *rnp;
 
 	/* Exclude any attempts to start a new grace period. */
-	spin_lock_irqsave(&rsp->onofflock, flags);
+	raw_spin_lock_irqsave(&rsp->onofflock, flags);
 
 	/* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
 	rnp = rdp->mynode;	/* this is the outgoing CPU's rnp. */
 	mask = rdp->grpmask;	/* rnp->grplo is constant. */
 	do {
-		spin_lock(&rnp->lock);		/* irqs already disabled. */
+		raw_spin_lock(&rnp->lock);	/* irqs already disabled. */
 		rnp->qsmaskinit &= ~mask;
 		if (rnp->qsmaskinit != 0) {
 			if (rnp != rdp->mynode)
-				spin_unlock(&rnp->lock); /* irqs remain disabled. */
+				raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
 			break;
 		}
 		if (rnp == rdp->mynode)
 			need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
 		else
-			spin_unlock(&rnp->lock); /* irqs remain disabled. */
+			raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
 		mask = rnp->grpmask;
 		rnp = rnp->parent;
 	} while (rnp != NULL);
@@ -980,12 +1038,12 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
 	 * because invoking rcu_report_unblock_qs_rnp() with ->onofflock
 	 * held leads to deadlock.
 	 */
-	spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
+	raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
 	rnp = rdp->mynode;
 	if (need_report & RCU_OFL_TASKS_NORM_GP)
 		rcu_report_unblock_qs_rnp(rnp, flags);
 	else
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 	if (need_report & RCU_OFL_TASKS_EXP_GP)
 		rcu_report_exp_rnp(rsp, rnp);
 
@@ -1103,8 +1161,6 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
  */
 void rcu_check_callbacks(int cpu, int user)
 {
-	if (!rcu_pending(cpu))
-		return; /* if nothing for RCU to do. */
 	if (user ||
 	    (idle_cpu(cpu) && rcu_scheduler_active &&
 	     !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
@@ -1136,7 +1192,8 @@ void rcu_check_callbacks(int cpu, int user)
 		rcu_bh_qs(cpu);
 	}
 	rcu_preempt_check_callbacks(cpu);
-	raise_softirq(RCU_SOFTIRQ);
+	if (rcu_pending(cpu))
+		raise_softirq(RCU_SOFTIRQ);
 }
 
 #ifdef CONFIG_SMP
@@ -1144,11 +1201,9 @@ void rcu_check_callbacks(int cpu, int user)
 /*
  * Scan the leaf rcu_node structures, processing dyntick state for any that
  * have not yet encountered a quiescent state, using the function specified.
- * Returns 1 if the current grace period ends while scanning (possibly
- * because we made it end).
+ * The caller must have suppressed start of new grace periods.
  */
-static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
-			       int (*f)(struct rcu_data *))
+static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
 {
 	unsigned long bit;
 	int cpu;
@@ -1158,13 +1213,13 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
 
 	rcu_for_each_leaf_node(rsp, rnp) {
 		mask = 0;
-		spin_lock_irqsave(&rnp->lock, flags);
-		if (rnp->completed != lastcomp) {
-			spin_unlock_irqrestore(&rnp->lock, flags);
-			return 1;
+		raw_spin_lock_irqsave(&rnp->lock, flags);
+		if (!rcu_gp_in_progress(rsp)) {
+			raw_spin_unlock_irqrestore(&rnp->lock, flags);
+			return;
 		}
 		if (rnp->qsmask == 0) {
-			spin_unlock_irqrestore(&rnp->lock, flags);
+			raw_spin_unlock_irqrestore(&rnp->lock, flags);
 			continue;
 		}
 		cpu = rnp->grplo;
@@ -1173,15 +1228,14 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
 			if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
 				mask |= bit;
 		}
-		if (mask != 0 && rnp->completed == lastcomp) {
+		if (mask != 0) {
 
 			/* rcu_report_qs_rnp() releases rnp->lock. */
 			rcu_report_qs_rnp(mask, rsp, rnp, flags);
 			continue;
 		}
-		spin_unlock_irqrestore(&rnp->lock, flags);
+		raw_spin_unlock_irqrestore(&rnp->lock, flags);
 	}
-	return 0;
 }
 
 /*
@@ -1191,83 +1245,65 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
 static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
 {
 	unsigned long flags;
-	long lastcomp;
 	struct rcu_node *rnp = rcu_get_root(rsp);
-	u8 signaled;
-	u8 forcenow;
-	u8 gpdone;
 
 	if (!rcu_gp_in_progress(rsp))
 		return;  /* No grace period in progress, nothing to force. */
-	if (!spin_trylock_irqsave(&rsp->fqslock, flags)) {
+	if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) {
 		rsp->n_force_qs_lh++; /* Inexact, can lose counts.  Tough! */
 		return;	/* Someone else is already on the job. */
 	}
-	if (relaxed &&
-	    (long)(rsp->jiffies_force_qs - jiffies) >= 0)
+	if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies))
 		goto unlock_fqs_ret; /* no emergency and done recently. */
 	rsp->n_force_qs++;
-	spin_lock(&rnp->lock);  /* irqs already disabled */
-	lastcomp = rsp->gpnum - 1;
-	signaled = rsp->signaled;
+	raw_spin_lock(&rnp->lock);  /* irqs already disabled */
 	rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
 	if(!rcu_gp_in_progress(rsp)) {
 		rsp->n_force_qs_ngp++;
-		spin_unlock(&rnp->lock);  /* irqs remain disabled */
+		raw_spin_unlock(&rnp->lock);  /* irqs remain disabled */
 		goto unlock_fqs_ret;  /* no GP in progress, time updated. */
 	}
 	rsp->fqs_active = 1;
-	switch (signaled) {
+	switch (rsp->signaled) {
 	case RCU_GP_IDLE:
 	case RCU_GP_INIT:
 
 		break; /* grace period idle or initializing, ignore. */
 
 	case RCU_SAVE_DYNTICK:
-
-		spin_unlock(&rnp->lock);  /* irqs remain disabled */
 		if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK)
 			break; /* So gcc recognizes the dead code. */
 
-		/* Record dyntick-idle state. */
-		gpdone = rcu_process_dyntick(rsp, lastcomp,
-					     dyntick_save_progress_counter);
-		spin_lock(&rnp->lock);  /* irqs already disabled */
-		if (gpdone)
-			break;
-		/* fall into next case. */
-
-	case RCU_SAVE_COMPLETED:
+		raw_spin_unlock(&rnp->lock);  /* irqs remain disabled */
 
-		/* Update state, record completion counter. */
-		forcenow = 0;
-		if (lastcomp + 1 == rsp->gpnum &&
-		    lastcomp == rsp->completed &&
-		    rsp->signaled == signaled) {
+		/* Record dyntick-idle state. */
+		force_qs_rnp(rsp, dyntick_save_progress_counter);
+		raw_spin_lock(&rnp->lock);  /* irqs already disabled */
+		if (rcu_gp_in_progress(rsp))
 			rsp->signaled = RCU_FORCE_QS;
-			rsp->completed_fqs = lastcomp;
-			forcenow = signaled == RCU_SAVE_COMPLETED;
-		}
-		if (!forcenow)
-			break;
-		/* fall into next case. */
+		break;
 
 	case RCU_FORCE_QS:
 
 		/* Check dyntick-idle state, send IPI to laggarts. */
-		spin_unlock(&rnp->lock);  /* irqs remain disabled */
-		gpdone = rcu_process_dyntick(rsp, rsp->completed_fqs,
-					     rcu_implicit_dynticks_qs);
+		raw_spin_unlock(&rnp->lock);  /* irqs remain disabled */
+		force_qs_rnp(rsp, rcu_implicit_dynticks_qs);
 
 		/* Leave state in case more forcing is required. */
 
-		spin_lock(&rnp->lock);  /* irqs already disabled */
+		raw_spin_lock(&rnp->lock);  /* irqs already disabled */
 		break;
 	}
 	rsp->fqs_active = 0;
-	spin_unlock(&rnp->lock);  /* irqs remain disabled */
+	if (rsp->fqs_need_gp) {
+		raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */
+		rsp->fqs_need_gp = 0;
+		rcu_start_gp(rsp, flags); /* releases rnp->lock */
+		return;
+	}
+	raw_spin_unlock(&rnp->lock);  /* irqs remain disabled */
 unlock_fqs_ret:
-	spin_unlock_irqrestore(&rsp->fqslock, flags);
+	raw_spin_unlock_irqrestore(&rsp->fqslock, flags);
 }
 
 #else /* #ifdef CONFIG_SMP */
@@ -1295,7 +1331,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
 	 * If an RCU GP has gone long enough, go check for dyntick
 	 * idle CPUs and, if needed, send resched IPIs.
 	 */
-	if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)
+	if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies))
 		force_quiescent_state(rsp, 1);
 
 	/*
@@ -1309,7 +1345,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
 
 	/* Does this CPU require a not-yet-started grace period? */
 	if (cpu_needs_another_gp(rsp, rdp)) {
-		spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags);
+		raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags);
 		rcu_start_gp(rsp, flags);  /* releases above lock */
 	}
 
@@ -1340,6 +1376,9 @@ static void rcu_process_callbacks(struct softirq_action *unused)
 	 * grace-period manipulations above.
 	 */
 	smp_mb(); /* See above block comment. */
+
+	/* If we are last CPU on way to dyntick-idle mode, accelerate it. */
+	rcu_needs_cpu_flush();
 }
 
 static void
@@ -1374,7 +1413,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
 		unsigned long nestflag;
 		struct rcu_node *rnp_root = rcu_get_root(rsp);
 
-		spin_lock_irqsave(&rnp_root->lock, nestflag);
+		raw_spin_lock_irqsave(&rnp_root->lock, nestflag);
 		rcu_start_gp(rsp, nestflag);  /* releases rnp_root->lock. */
 	}
 
@@ -1392,7 +1431,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
 			force_quiescent_state(rsp, 0);
 		rdp->n_force_qs_snap = rsp->n_force_qs;
 		rdp->qlen_last_fqs_check = rdp->qlen;
-	} else if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)
+	} else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies))
 		force_quiescent_state(rsp, 1);
 	local_irq_restore(flags);
 }
@@ -1445,11 +1484,13 @@ void synchronize_sched(void)
 	if (rcu_blocking_is_gp())
 		return;
 
+	init_rcu_head_on_stack(&rcu.head);
 	init_completion(&rcu.completion);
 	/* Will wake me after RCU finished. */
 	call_rcu_sched(&rcu.head, wakeme_after_rcu);
 	/* Wait for it. */
 	wait_for_completion(&rcu.completion);
+	destroy_rcu_head_on_stack(&rcu.head);
 }
 EXPORT_SYMBOL_GPL(synchronize_sched);
 
@@ -1469,11 +1510,13 @@ void synchronize_rcu_bh(void)
 	if (rcu_blocking_is_gp())
 		return;
 
+	init_rcu_head_on_stack(&rcu.head);
 	init_completion(&rcu.completion);
 	/* Will wake me after RCU finished. */
 	call_rcu_bh(&rcu.head, wakeme_after_rcu);
 	/* Wait for it. */
 	wait_for_completion(&rcu.completion);
+	destroy_rcu_head_on_stack(&rcu.head);
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
 
@@ -1494,8 +1537,20 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
 	check_cpu_stall(rsp, rdp);
 
 	/* Is the RCU core waiting for a quiescent state from this CPU? */
-	if (rdp->qs_pending) {
+	if (rdp->qs_pending && !rdp->passed_quiesc) {
+
+		/*
+		 * If force_quiescent_state() coming soon and this CPU
+		 * needs a quiescent state, and this is either RCU-sched
+		 * or RCU-bh, force a local reschedule.
+		 */
 		rdp->n_rp_qs_pending++;
+		if (!rdp->preemptable &&
+		    ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1,
+				 jiffies))
+			set_need_resched();
+	} else if (rdp->qs_pending && rdp->passed_quiesc) {
+		rdp->n_rp_report_qs++;
 		return 1;
 	}
 
@@ -1525,7 +1580,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
 
 	/* Has an RCU GP gone long enough to send resched IPIs &c? */
 	if (rcu_gp_in_progress(rsp) &&
-	    ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)) {
+	    ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) {
 		rdp->n_rp_need_fqs++;
 		return 1;
 	}
@@ -1550,10 +1605,9 @@ static int rcu_pending(int cpu)
 /*
  * Check to see if any future RCU-related work will need to be done
  * by the current CPU, even if none need be done immediately, returning
- * 1 if so.  This function is part of the RCU implementation; it is -not-
- * an exported member of the RCU API.
+ * 1 if so.
  */
-int rcu_needs_cpu(int cpu)
+static int rcu_needs_cpu_quick_check(int cpu)
 {
 	/* RCU callbacks either ready or pending? */
 	return per_cpu(rcu_sched_data, cpu).nxtlist ||
@@ -1561,21 +1615,6 @@ int rcu_needs_cpu(int cpu)
 	       rcu_preempt_needs_cpu(cpu);
 }
 
-/*
- * This function is invoked towards the end of the scheduler's initialization
- * process.  Before this is called, the idle task might contain
- * RCU read-side critical sections (during which time, this idle
- * task is booting the system).  After this function is called, the
- * idle tasks are prohibited from containing RCU read-side critical
- * sections.
- */
-void rcu_scheduler_starting(void)
-{
-	WARN_ON(num_online_cpus() != 1);
-	WARN_ON(nr_context_switches() > 0);
-	rcu_scheduler_active = 1;
-}
-
 static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};
 static atomic_t rcu_barrier_cpu_count;
 static DEFINE_MUTEX(rcu_barrier_mutex);
@@ -1664,7 +1703,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	/* Set up local state, ensuring consistent view of global state. */
-	spin_lock_irqsave(&rnp->lock, flags);
+	raw_spin_lock_irqsave(&rnp->lock, flags);
 	rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
 	rdp->nxtlist = NULL;
 	for (i = 0; i < RCU_NEXT_SIZE; i++)
@@ -1674,7 +1713,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 	rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
 #endif /* #ifdef CONFIG_NO_HZ */
 	rdp->cpu = cpu;
-	spin_unlock_irqrestore(&rnp->lock, flags);
+	raw_spin_unlock_irqrestore(&rnp->lock, flags);
 }
 
 /*
@@ -1692,7 +1731,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	/* Set up local state, ensuring consistent view of global state. */
-	spin_lock_irqsave(&rnp->lock, flags);
+	raw_spin_lock_irqsave(&rnp->lock, flags);
 	rdp->passed_quiesc = 0;  /* We could be racing with new GP, */
 	rdp->qs_pending = 1;	 /*  so set up to respond to current GP. */
 	rdp->beenonline = 1;	 /* We have now been online. */
@@ -1700,7 +1739,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
 	rdp->qlen_last_fqs_check = 0;
 	rdp->n_force_qs_snap = rsp->n_force_qs;
 	rdp->blimit = blimit;
-	spin_unlock(&rnp->lock);		/* irqs remain disabled. */
+	raw_spin_unlock(&rnp->lock);		/* irqs remain disabled. */
 
 	/*
 	 * A new grace period might start here.  If so, we won't be part
@@ -1708,14 +1747,14 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
 	 */
 
 	/* Exclude any attempts to start a new GP on large systems. */
-	spin_lock(&rsp->onofflock);		/* irqs already disabled. */
+	raw_spin_lock(&rsp->onofflock);		/* irqs already disabled. */
 
 	/* Add CPU to rcu_node bitmasks. */
 	rnp = rdp->mynode;
 	mask = rdp->grpmask;
 	do {
 		/* Exclude any attempts to start a new GP on small systems. */
-		spin_lock(&rnp->lock);	/* irqs already disabled. */
+		raw_spin_lock(&rnp->lock);	/* irqs already disabled. */
 		rnp->qsmaskinit |= mask;
 		mask = rnp->grpmask;
 		if (rnp == rdp->mynode) {
@@ -1723,11 +1762,11 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
 			rdp->completed = rnp->completed;
 			rdp->passed_quiesc_completed = rnp->completed - 1;
 		}
-		spin_unlock(&rnp->lock); /* irqs already disabled. */
+		raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
 		rnp = rnp->parent;
 	} while (rnp != NULL && !(rnp->qsmaskinit & mask));
 
-	spin_unlock_irqrestore(&rsp->onofflock, flags);
+	raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
 }
 
 static void __cpuinit rcu_online_cpu(int cpu)
@@ -1779,6 +1818,21 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
 }
 
 /*
+ * This function is invoked towards the end of the scheduler's initialization
+ * process.  Before this is called, the idle task might contain
+ * RCU read-side critical sections (during which time, this idle
+ * task is booting the system).  After this function is called, the
+ * idle tasks are prohibited from containing RCU read-side critical
+ * sections.  This function also enables RCU lockdep checking.
+ */
+void rcu_scheduler_starting(void)
+{
+	WARN_ON(num_online_cpus() != 1);
+	WARN_ON(nr_context_switches() > 0);
+	rcu_scheduler_active = 1;
+}
+
+/*
  * Compute the per-level fanout, either using the exact fanout specified
  * or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT.
  */
@@ -1811,11 +1865,17 @@ static void __init rcu_init_levelspread(struct rcu_state *rsp)
  */
 static void __init rcu_init_one(struct rcu_state *rsp)
 {
+	static char *buf[] = { "rcu_node_level_0",
+			       "rcu_node_level_1",
+			       "rcu_node_level_2",
+			       "rcu_node_level_3" };  /* Match MAX_RCU_LVLS */
 	int cpustride = 1;
 	int i;
 	int j;
 	struct rcu_node *rnp;
 
+	BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf));  /* Fix buf[] init! */
+
 	/* Initialize the level-tracking arrays. */
 
 	for (i = 1; i < NUM_RCU_LVLS; i++)
@@ -1828,8 +1888,9 @@ static void __init rcu_init_one(struct rcu_state *rsp)
 		cpustride *= rsp->levelspread[i];
 		rnp = rsp->level[i];
 		for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
-			spin_lock_init(&rnp->lock);
-			lockdep_set_class(&rnp->lock, &rcu_node_class[i]);
+			raw_spin_lock_init(&rnp->lock);
+			lockdep_set_class_and_name(&rnp->lock,
+						   &rcu_node_class[i], buf[i]);
 			rnp->gpnum = 0;
 			rnp->qsmask = 0;
 			rnp->qsmaskinit = 0;
@@ -1854,6 +1915,14 @@ static void __init rcu_init_one(struct rcu_state *rsp)
 			INIT_LIST_HEAD(&rnp->blocked_tasks[3]);
 		}
 	}
+
+	rnp = rsp->level[NUM_RCU_LVLS - 1];
+	for_each_possible_cpu(i) {
+		while (i > rnp->grphi)
+			rnp++;
+		rsp->rda[i]->mynode = rnp;
+		rcu_boot_init_percpu_data(i, rsp);
+	}
 }
 
 /*
@@ -1864,32 +1933,18 @@ static void __init rcu_init_one(struct rcu_state *rsp)
 #define RCU_INIT_FLAVOR(rsp, rcu_data) \
 do { \
 	int i; \
-	int j; \
-	struct rcu_node *rnp; \
 	\
-	rcu_init_one(rsp); \
-	rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \
-	j = 0; \
 	for_each_possible_cpu(i) { \
-		if (i > rnp[j].grphi) \
-			j++; \
-		per_cpu(rcu_data, i).mynode = &rnp[j]; \
 		(rsp)->rda[i] = &per_cpu(rcu_data, i); \
-		rcu_boot_init_percpu_data(i, rsp); \
 	} \
+	rcu_init_one(rsp); \
 } while (0)
 
 void __init rcu_init(void)
 {
-	int i;
+	int cpu;
 
 	rcu_bootup_announce();
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-	printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-#if NUM_RCU_LVL_4 != 0
-	printk(KERN_INFO "Experimental four-level hierarchy is enabled.\n");
-#endif /* #if NUM_RCU_LVL_4 != 0 */
 	RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data);
 	RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data);
 	__rcu_init_preempt();
@@ -1901,8 +1956,9 @@ void __init rcu_init(void)
 	 * or the scheduler are operational.
 	 */
 	cpu_notifier(rcu_cpu_notify, 0);
-	for_each_online_cpu(i)
-		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)i);
+	for_each_online_cpu(cpu)
+		rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
+	check_cpu_stall_init();
 }
 
 #include "rcutree_plugin.h"