1 files changed, 229 insertions, 124 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index dd4aea806f8e..ba06207b1dd3 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -36,7 +36,7 @@
 #include <linux/interrupt.h>
 #include <linux/sched.h>
 #include <linux/nmi.h>
-#include <asm/atomic.h>
+#include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/completion.h>
@@ -47,6 +47,9 @@
 #include <linux/mutex.h>
 #include <linux/time.h>
 #include <linux/kernel_stat.h>
+#include <linux/wait.h>
+#include <linux/kthread.h>
+#include <linux/prefetch.h>
 
 #include "rcutree.h"
 
@@ -79,10 +82,67 @@ 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 struct rcu_state *rcu_state;
+
+/*
+ * The rcu_scheduler_active variable transitions from zero to one just
+ * before the first task is spawned.  So when this variable is zero, RCU
+ * can assume that there is but one task, allowing RCU to (for example)
+ * optimized synchronize_sched() to a simple barrier().  When this variable
+ * is one, RCU must actually do all the hard work required to detect real
+ * grace periods.  This variable is also used to suppress boot-time false
+ * positives from lockdep-RCU error checking.
+ */
 int rcu_scheduler_active __read_mostly;
 EXPORT_SYMBOL_GPL(rcu_scheduler_active);
 
 /*
+ * The rcu_scheduler_fully_active variable transitions from zero to one
+ * during the early_initcall() processing, which is after the scheduler
+ * is capable of creating new tasks.  So RCU processing (for example,
+ * creating tasks for RCU priority boosting) must be delayed until after
+ * rcu_scheduler_fully_active transitions from zero to one.  We also
+ * currently delay invocation of any RCU callbacks until after this point.
+ *
+ * It might later prove better for people registering RCU callbacks during
+ * early boot to take responsibility for these callbacks, but one step at
+ * a time.
+ */
+static int rcu_scheduler_fully_active __read_mostly;
+
+#ifdef CONFIG_RCU_BOOST
+
+/*
+ * Control variables for per-CPU and per-rcu_node kthreads.  These
+ * handle all flavors of RCU.
+ */
+static DEFINE_PER_CPU(struct task_struct *, rcu_cpu_kthread_task);
+DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
+DEFINE_PER_CPU(int, rcu_cpu_kthread_cpu);
+DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
+DEFINE_PER_CPU(char, rcu_cpu_has_work);
+
+#endif /* #ifdef CONFIG_RCU_BOOST */
+
+static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
+static void invoke_rcu_core(void);
+static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
+
+#define RCU_KTHREAD_PRIO 1      /* RT priority for per-CPU kthreads. */
+
+/*
+ * Track the rcutorture test sequence number and the update version
+ * number within a given test.  The rcutorture_testseq is incremented
+ * on every rcutorture module load and unload, so has an odd value
+ * when a test is running.  The rcutorture_vernum is set to zero
+ * when rcutorture starts and is incremented on each rcutorture update.
+ * These variables enable correlating rcutorture output with the
+ * RCU tracing information.
+ */
+unsigned long rcutorture_testseq;
+unsigned long rcutorture_vernum;
+
+/*
  * Return true if an RCU grace period is in progress.  The ACCESS_ONCE()s
  * permit this function to be invoked without holding the root rcu_node
  * structure's ->lock, but of course results can be subject to change.
@@ -124,11 +184,12 @@ void rcu_note_context_switch(int cpu)
         rcu_sched_qs(cpu);
         rcu_preempt_note_context_switch(cpu);
 }
+EXPORT_SYMBOL_GPL(rcu_note_context_switch);
 
 #ifdef CONFIG_NO_HZ
 DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
         .dynticks_nesting = 1,
-        .dynticks = 1,
+        .dynticks = ATOMIC_INIT(1),
 };
 #endif /* #ifdef CONFIG_NO_HZ */
 
@@ -140,10 +201,8 @@ module_param(blimit, int, 0);
 module_param(qhimark, int, 0);
 module_param(qlowmark, int, 0);
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-int rcu_cpu_stall_suppress __read_mostly = RCU_CPU_STALL_SUPPRESS_INIT;
+int rcu_cpu_stall_suppress __read_mostly;
 module_param(rcu_cpu_stall_suppress, int, 0644);
-#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
 
 static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
 static int rcu_pending(int cpu);
@@ -176,6 +235,31 @@ void rcu_bh_force_quiescent_state(void)
 EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
 
 /*
+ * Record the number of times rcutorture tests have been initiated and
+ * terminated.  This information allows the debugfs tracing stats to be
+ * correlated to the rcutorture messages, even when the rcutorture module
+ * is being repeatedly loaded and unloaded.  In other words, we cannot
+ * store this state in rcutorture itself.
+ */
+void rcutorture_record_test_transition(void)
+{
+        rcutorture_testseq++;
+        rcutorture_vernum = 0;
+}
+EXPORT_SYMBOL_GPL(rcutorture_record_test_transition);
+
+/*
+ * Record the number of writer passes through the current rcutorture test.
+ * This is also used to correlate debugfs tracing stats with the rcutorture
+ * messages.
+ */
+void rcutorture_record_progress(unsigned long vernum)
+{
+        rcutorture_vernum++;
+}
+EXPORT_SYMBOL_GPL(rcutorture_record_progress);
+
+/*
  * Force a quiescent state for RCU-sched.
  */
 void rcu_sched_force_quiescent_state(void)
@@ -234,8 +318,8 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp)
                 return 1;
         }
 
-        /* If preemptable RCU, no point in sending reschedule IPI. */
-        if (rdp->preemptable)
+        /* If preemptible RCU, no point in sending reschedule IPI. */
+        if (rdp->preemptible)
                 return 0;
 
         /* The CPU is online, so send it a reschedule IPI. */
@@ -264,13 +348,25 @@ void rcu_enter_nohz(void)
         unsigned long flags;
         struct rcu_dynticks *rdtp;
 
-        smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
         local_irq_save(flags);
         rdtp = &__get_cpu_var(rcu_dynticks);
-        rdtp->dynticks++;
-        rdtp->dynticks_nesting--;
-        WARN_ON_ONCE(rdtp->dynticks & 0x1);
+        if (--rdtp->dynticks_nesting) {
+                local_irq_restore(flags);
+                return;
+        }
+        /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
+        smp_mb__before_atomic_inc();  /* See above. */
+        atomic_inc(&rdtp->dynticks);
+        smp_mb__after_atomic_inc();  /* Force ordering with next sojourn. */
+        WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
         local_irq_restore(flags);
+
+        /* If the interrupt queued a callback, get out of dyntick mode. */
+        if (in_irq() &&
+            (__get_cpu_var(rcu_sched_data).nxtlist ||
+             __get_cpu_var(rcu_bh_data).nxtlist ||
+             rcu_preempt_needs_cpu(smp_processor_id())))
+                set_need_resched();
 }
 
 /*
@@ -286,11 +382,16 @@ void rcu_exit_nohz(void)
 
         local_irq_save(flags);
         rdtp = &__get_cpu_var(rcu_dynticks);
-        rdtp->dynticks++;
-        rdtp->dynticks_nesting++;
-        WARN_ON_ONCE(!(rdtp->dynticks & 0x1));
+        if (rdtp->dynticks_nesting++) {
+                local_irq_restore(flags);
+                return;
+        }
+        smp_mb__before_atomic_inc();  /* Force ordering w/previous sojourn. */
+        atomic_inc(&rdtp->dynticks);
+        /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
+        smp_mb__after_atomic_inc();  /* See above. */
+        WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
         local_irq_restore(flags);
-        smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
 }
 
 /**
@@ -304,11 +405,15 @@ void rcu_nmi_enter(void)
 {
         struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
 
-        if (rdtp->dynticks & 0x1)
+        if (rdtp->dynticks_nmi_nesting == 0 &&
+            (atomic_read(&rdtp->dynticks) & 0x1))
                 return;
-        rdtp->dynticks_nmi++;
-        WARN_ON_ONCE(!(rdtp->dynticks_nmi & 0x1));
-        smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
+        rdtp->dynticks_nmi_nesting++;
+        smp_mb__before_atomic_inc();  /* Force delay from prior write. */
+        atomic_inc(&rdtp->dynticks);
+        /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */
+        smp_mb__after_atomic_inc();  /* See above. */
+        WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1));
 }
 
 /**
@@ -322,11 +427,14 @@ void rcu_nmi_exit(void)
 {
         struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
 
-        if (rdtp->dynticks & 0x1)
+        if (rdtp->dynticks_nmi_nesting == 0 ||
+            --rdtp->dynticks_nmi_nesting != 0)
                 return;
-        smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
-        rdtp->dynticks_nmi++;
-        WARN_ON_ONCE(rdtp->dynticks_nmi & 0x1);
+        /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */
+        smp_mb__before_atomic_inc();  /* See above. */
+        atomic_inc(&rdtp->dynticks);
+        smp_mb__after_atomic_inc();  /* Force delay to next write. */
+        WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1);
 }
 
 /**
@@ -337,13 +445,7 @@ void rcu_nmi_exit(void)
  */
 void rcu_irq_enter(void)
 {
-        struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
-
-        if (rdtp->dynticks_nesting++)
-                return;
-        rdtp->dynticks++;
-        WARN_ON_ONCE(!(rdtp->dynticks & 0x1));
-        smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
+        rcu_exit_nohz();
 }
 
 /**
@@ -355,18 +457,7 @@ void rcu_irq_enter(void)
  */
 void rcu_irq_exit(void)
 {
-        struct rcu_dynticks *rdtp = &__get_cpu_var(rcu_dynticks);
-
-        if (--rdtp->dynticks_nesting)
-                return;
-        smp_mb(); /* CPUs seeing ++ must see prior RCU read-side crit sects */
-        rdtp->dynticks++;
-        WARN_ON_ONCE(rdtp->dynticks & 0x1);
-
-        /* If the interrupt queued a callback, get out of dyntick mode. */
-        if (__this_cpu_read(rcu_sched_data.nxtlist) ||
-            __this_cpu_read(rcu_bh_data.nxtlist))
-                set_need_resched();
+        rcu_enter_nohz();
 }
 
 #ifdef CONFIG_SMP
@@ -378,19 +469,8 @@ void rcu_irq_exit(void)
  */
 static int dyntick_save_progress_counter(struct rcu_data *rdp)
 {
-        int ret;
-        int snap;
-        int snap_nmi;
-
-        snap = rdp->dynticks->dynticks;
-        snap_nmi = rdp->dynticks->dynticks_nmi;
-        smp_mb();       /* Order sampling of snap with end of grace period. */
-        rdp->dynticks_snap = snap;
-        rdp->dynticks_nmi_snap = snap_nmi;
-        ret = ((snap & 0x1) == 0) && ((snap_nmi & 0x1) == 0);
-        if (ret)
-                rdp->dynticks_fqs++;
-        return ret;
+        rdp->dynticks_snap = atomic_add_return(0, &rdp->dynticks->dynticks);
+        return 0;
 }
 
 /*
@@ -401,16 +481,11 @@ static int dyntick_save_progress_counter(struct rcu_data *rdp)
  */
 static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 {
-        long curr;
-        long curr_nmi;
-        long snap;
-        long snap_nmi;
+        unsigned long curr;
+        unsigned long snap;
 
-        curr = rdp->dynticks->dynticks;
-        snap = rdp->dynticks_snap;
-        curr_nmi = rdp->dynticks->dynticks_nmi;
-        snap_nmi = rdp->dynticks_nmi_snap;
-        smp_mb(); /* force ordering with cpu entering/leaving dynticks. */
+        curr = (unsigned long)atomic_add_return(0, &rdp->dynticks->dynticks);
+        snap = (unsigned long)rdp->dynticks_snap;
 
         /*
          * If the CPU passed through or entered a dynticks idle phase with
@@ -420,8 +495,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
          * read-side critical section that started before the beginning
          * of the current RCU grace period.
          */
-        if ((curr != snap || (curr & 0x1) == 0) &&
-            (curr_nmi != snap_nmi || (curr_nmi & 0x1) == 0)) {
+        if ((curr & 0x1) == 0 || ULONG_CMP_GE(curr, snap + 2)) {
                 rdp->dynticks_fqs++;
                 return 1;
         }
@@ -450,8 +524,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 
 #endif /* #else #ifdef CONFIG_NO_HZ */
 
-#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
-
 int rcu_cpu_stall_suppress __read_mostly;
 
 static void record_gp_stall_check_time(struct rcu_state *rsp)
@@ -537,21 +609,24 @@ static void print_cpu_stall(struct rcu_state *rsp)
 
 static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 {
-        long delta;
+        unsigned long j;
+        unsigned long js;
         struct rcu_node *rnp;
 
         if (rcu_cpu_stall_suppress)
                 return;
-        delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall);
+        j = ACCESS_ONCE(jiffies);
+        js = ACCESS_ONCE(rsp->jiffies_stall);
         rnp = rdp->mynode;
-        if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && delta >= 0) {
+        if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && ULONG_CMP_GE(j, js)) {
 
                 /* We haven't checked in, so go dump stack. */
                 print_cpu_stall(rsp);
 
-        } else if (rcu_gp_in_progress(rsp) && delta >= RCU_STALL_RAT_DELAY) {
+        } else if (rcu_gp_in_progress(rsp) &&
+                   ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) {
 
-                /* They had two time units to dump stack, so complain. */
+                /* They had a few time units to dump stack, so complain. */
                 print_other_cpu_stall(rsp);
         }
 }
@@ -587,26 +662,6 @@ 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)
-{
-}
-
-static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-}
-
-void rcu_cpu_stall_reset(void)
-{
-}
-
-static void __init check_cpu_stall_init(void)
-{
-}
-
-#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
-
 /*
  * Update CPU-local rcu_data state to record the newly noticed grace period.
  * This is used both when we started the grace period and when we notice
@@ -809,6 +864,7 @@ 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);
+                rcu_preempt_boost_start_gp(rnp);
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
                 return;
         }
@@ -844,6 +900,7 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
                 rnp->completed = rsp->completed;
                 if (rnp == rdp->mynode)
                         rcu_start_gp_per_cpu(rsp, rnp, rdp);
+                rcu_preempt_boost_start_gp(rnp);
                 raw_spin_unlock(&rnp->lock);    /* irqs remain disabled. */
         }
 
@@ -864,7 +921,18 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
         __releases(rcu_get_root(rsp)->lock)
 {
+        unsigned long gp_duration;
+
         WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
+
+        /*
+         * Ensure that all grace-period and pre-grace-period activity
+         * is seen before the assignment to rsp->completed.
+         */
+        smp_mb(); /* See above block comment. */
+        gp_duration = jiffies - rsp->gp_start;
+        if (gp_duration > rsp->gp_max)
+                rsp->gp_max = gp_duration;
         rsp->completed = rsp->gpnum;
         rsp->signaled = RCU_GP_IDLE;
         rcu_start_gp(rsp, flags);  /* releases root node's rnp->lock. */
@@ -894,7 +962,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
                         return;
                 }
                 rnp->qsmask &= ~mask;
-                if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) {
+                if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
 
                         /* Other bits still set at this level, so done. */
                         raw_spin_unlock_irqrestore(&rnp->lock, flags);
@@ -1037,6 +1105,8 @@ static void rcu_send_cbs_to_online(struct rcu_state *rsp)
 /*
  * Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy
  * and move all callbacks from the outgoing CPU to the current one.
+ * There can only be one CPU hotplug operation at a time, so no other
+ * CPU can be attempting to update rcu_cpu_kthread_task.
  */
 static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
 {
@@ -1046,6 +1116,8 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
         struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
         struct rcu_node *rnp;
 
+        rcu_stop_cpu_kthread(cpu);
+
         /* Exclude any attempts to start a new grace period. */
         raw_spin_lock_irqsave(&rsp->onofflock, flags);
 
@@ -1082,6 +1154,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
         if (need_report & RCU_OFL_TASKS_EXP_GP)
                 rcu_report_exp_rnp(rsp, rnp);
+        rcu_node_kthread_setaffinity(rnp, -1);
 }
 
 /*
@@ -1143,7 +1216,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
                 next = list->next;
                 prefetch(next);
                 debug_rcu_head_unqueue(list);
-                list->func(list);
+                __rcu_reclaim(list);
                 list = next;
                 if (++count >= rdp->blimit)
                         break;
@@ -1179,7 +1252,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 
         /* Re-raise the RCU softirq if there are callbacks remaining. */
         if (cpu_has_callbacks_ready_to_invoke(rdp))
-                raise_softirq(RCU_SOFTIRQ);
+                invoke_rcu_core();
 }
 
 /*
@@ -1225,7 +1298,7 @@ void rcu_check_callbacks(int cpu, int user)
         }
         rcu_preempt_check_callbacks(cpu);
         if (rcu_pending(cpu))
-                raise_softirq(RCU_SOFTIRQ);
+                invoke_rcu_core();
 }
 
 #ifdef CONFIG_SMP
@@ -1233,6 +1306,8 @@ 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.
+ * Also initiate boosting for any threads blocked on the root rcu_node.
+ *
  * The caller must have suppressed start of new grace periods.
  */
 static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
@@ -1251,7 +1326,7 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
                         return;
                 }
                 if (rnp->qsmask == 0) {
-                        raw_spin_unlock_irqrestore(&rnp->lock, flags);
+                        rcu_initiate_boost(rnp, flags); /* releases rnp->lock */
                         continue;
                 }
                 cpu = rnp->grplo;
@@ -1269,6 +1344,11 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
                 }
                 raw_spin_unlock_irqrestore(&rnp->lock, flags);
         }
+        rnp = rcu_get_root(rsp);
+        if (rnp->qsmask == 0) {
+                raw_spin_lock_irqsave(&rnp->lock, flags);
+                rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
+        }
 }
 
 /*
@@ -1383,7 +1463,8 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
         }
 
         /* If there are callbacks ready, invoke them. */
-        rcu_do_batch(rsp, rdp);
+        if (cpu_has_callbacks_ready_to_invoke(rdp))
+                invoke_rcu_callbacks(rsp, rdp);
 }
 
 /*
@@ -1391,29 +1472,37 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
  */
 static void rcu_process_callbacks(struct softirq_action *unused)
 {
-        /*
-         * Memory references from any prior RCU read-side critical sections
-         * executed by the interrupted code must be seen before any RCU
-         * grace-period manipulations below.
-         */
-        smp_mb(); /* See above block comment. */
-
         __rcu_process_callbacks(&rcu_sched_state,
                                 &__get_cpu_var(rcu_sched_data));
         __rcu_process_callbacks(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
         rcu_preempt_process_callbacks();
 
-        /*
-         * Memory references from any later RCU read-side critical sections
-         * executed by the interrupted code must be seen after any RCU
-         * 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();
 }
 
+/*
+ * Wake up the current CPU's kthread.  This replaces raise_softirq()
+ * in earlier versions of RCU.  Note that because we are running on
+ * the current CPU with interrupts disabled, the rcu_cpu_kthread_task
+ * cannot disappear out from under us.
+ */
+static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
+{
+        if (unlikely(!ACCESS_ONCE(rcu_scheduler_fully_active)))
+                return;
+        if (likely(!rsp->boost)) {
+                rcu_do_batch(rsp, rdp);
+                return;
+        }
+        invoke_rcu_callbacks_kthread();
+}
+
+static void invoke_rcu_core(void)
+{
+        raise_softirq(RCU_SOFTIRQ);
+}
+
 static void
 __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
            struct rcu_state *rsp)
@@ -1439,6 +1528,13 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
         /* Add the callback to our list. */
         *rdp->nxttail[RCU_NEXT_TAIL] = head;
         rdp->nxttail[RCU_NEXT_TAIL] = &head->next;
+        rdp->qlen++;
+
+        /* If interrupts were disabled, don't dive into RCU core. */
+        if (irqs_disabled_flags(flags)) {
+                local_irq_restore(flags);
+                return;
+        }
 
         /*
          * Force the grace period if too many callbacks or too long waiting.
@@ -1447,7 +1543,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
          * invoking force_quiescent_state() if the newly enqueued callback
          * is the only one waiting for a grace period to complete.
          */
-        if (unlikely(++rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) {
+        if (unlikely(rdp->qlen > rdp->qlen_last_fqs_check + qhimark)) {
 
                 /* Are we ignoring a completed grace period? */
                 rcu_process_gp_end(rsp, rdp);
@@ -1583,7 +1679,7 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
                  * or RCU-bh, force a local reschedule.
                  */
                 rdp->n_rp_qs_pending++;
-                if (!rdp->preemptable &&
+                if (!rdp->preemptible &&
                     ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1,
                                  jiffies))
                         set_need_resched();
@@ -1760,7 +1856,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
  * that this CPU cannot possibly have any RCU callbacks in flight yet.
  */
 static void __cpuinit
-rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
+rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible)
 {
         unsigned long flags;
         unsigned long mask;
@@ -1772,7 +1868,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
         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. */
-        rdp->preemptable = preemptable;
+        rdp->preemptible = preemptible;
         rdp->qlen_last_fqs_check = 0;
         rdp->n_force_qs_snap = rsp->n_force_qs;
         rdp->blimit = blimit;
@@ -1806,7 +1902,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
         raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
 }
 
-static void __cpuinit rcu_online_cpu(int cpu)
+static void __cpuinit rcu_prepare_cpu(int cpu)
 {
         rcu_init_percpu_data(cpu, &rcu_sched_state, 0);
         rcu_init_percpu_data(cpu, &rcu_bh_state, 0);
@@ -1820,11 +1916,23 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
                                     unsigned long action, void *hcpu)
 {
         long cpu = (long)hcpu;
+        struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
+        struct rcu_node *rnp = rdp->mynode;
 
         switch (action) {
         case CPU_UP_PREPARE:
         case CPU_UP_PREPARE_FROZEN:
-                rcu_online_cpu(cpu);
+                rcu_prepare_cpu(cpu);
+                rcu_prepare_kthreads(cpu);
+                break;
+        case CPU_ONLINE:
+        case CPU_DOWN_FAILED:
+                rcu_node_kthread_setaffinity(rnp, -1);
+                rcu_cpu_kthread_setrt(cpu, 1);
+                break;
+        case CPU_DOWN_PREPARE:
+                rcu_node_kthread_setaffinity(rnp, cpu);
+                rcu_cpu_kthread_setrt(cpu, 0);
                 break;
         case CPU_DYING:
         case CPU_DYING_FROZEN:
@@ -1943,10 +2051,7 @@ static void __init rcu_init_one(struct rcu_state *rsp,
                                               j / rsp->levelspread[i - 1];
                         }
                         rnp->level = i;
-                        INIT_LIST_HEAD(&rnp->blocked_tasks[0]);
-                        INIT_LIST_HEAD(&rnp->blocked_tasks[1]);
-                        INIT_LIST_HEAD(&rnp->blocked_tasks[2]);
-                        INIT_LIST_HEAD(&rnp->blocked_tasks[3]);
+                        INIT_LIST_HEAD(&rnp->blkd_tasks);
                 }
         }
 
@@ -1968,7 +2073,7 @@ void __init rcu_init(void)
         rcu_init_one(&rcu_sched_state, &rcu_sched_data);
         rcu_init_one(&rcu_bh_state, &rcu_bh_data);
         __rcu_init_preempt();
-        open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+         open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
 
         /*
          * We don't need protection against CPU-hotplug here because