Merge remote branch 'linus/master' into x86/bootmem

1 files changed, 342 insertions, 151 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 705f02ac7433..53ae9598f798 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -46,20 +46,24 @@
 #include <linux/cpu.h>
 #include <linux/mutex.h>
 #include <linux/time.h>
+#include <linux/kernel_stat.h>
 
 #include "rcutree.h"
 
 /* Data structures. */
 
+static struct lock_class_key rcu_node_class[NUM_RCU_LVLS];
+
 #define RCU_STATE_INITIALIZER(name) { \
         .level = { &name.node[0] }, \
         .levelcnt = { \
                 NUM_RCU_LVL_0,  /* root of hierarchy. */ \
                 NUM_RCU_LVL_1, \
                 NUM_RCU_LVL_2, \
-                NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \
+                NUM_RCU_LVL_3, \
+                NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \
         }, \
-        .signaled = RCU_SIGNAL_INIT, \
+        .signaled = RCU_GP_IDLE, \
         .gpnum = -300, \
         .completed = -300, \
         .onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \
@@ -77,6 +81,8 @@ 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;
+
 
 /*
  * Return true if an RCU grace period is in progress.  The ACCESS_ONCE()s
@@ -98,7 +104,7 @@ void rcu_sched_qs(int cpu)
         struct rcu_data *rdp;
 
         rdp = &per_cpu(rcu_sched_data, cpu);
-        rdp->passed_quiesc_completed = rdp->completed;
+        rdp->passed_quiesc_completed = rdp->gpnum - 1;
         barrier();
         rdp->passed_quiesc = 1;
         rcu_preempt_note_context_switch(cpu);
@@ -109,7 +115,7 @@ void rcu_bh_qs(int cpu)
         struct rcu_data *rdp;
 
         rdp = &per_cpu(rcu_bh_data, cpu);
-        rdp->passed_quiesc_completed = rdp->completed;
+        rdp->passed_quiesc_completed = rdp->gpnum - 1;
         barrier();
         rdp->passed_quiesc = 1;
 }
@@ -335,28 +341,9 @@ void rcu_irq_exit(void)
                 set_need_resched();
 }
 
-/*
- * Record the specified "completed" value, which is later used to validate
- * dynticks counter manipulations.  Specify "rsp->completed - 1" to
- * unconditionally invalidate any future dynticks manipulations (which is
- * useful at the beginning of a grace period).
- */
-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
-{
-        rsp->dynticks_completed = comp;
-}
-
 #ifdef CONFIG_SMP
 
 /*
- * Recall the previously recorded value of the completion for dynticks.
- */
-static long dyntick_recall_completed(struct rcu_state *rsp)
-{
-        return rsp->dynticks_completed;
-}
-
-/*
  * Snapshot the specified CPU's dynticks counter so that we can later
  * credit them with an implicit quiescent state.  Return 1 if this CPU
  * is in dynticks idle mode, which is an extended quiescent state.
@@ -419,24 +406,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 
 #else /* #ifdef CONFIG_NO_HZ */
 
-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
-{
-}
-
 #ifdef CONFIG_SMP
 
-/*
- * If there are no dynticks, then the only way that a CPU can passively
- * be in a quiescent state is to be offline.  Unlike dynticks idle, which
- * is a point in time during the prior (already finished) grace period,
- * an offline CPU is always in a quiescent state, and thus can be
- * unconditionally applied.  So just return the current value of completed.
- */
-static long dyntick_recall_completed(struct rcu_state *rsp)
-{
-        return rsp->completed;
-}
-
 static int dyntick_save_progress_counter(struct rcu_data *rdp)
 {
         return 0;
@@ -553,13 +524,33 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 /*
  * 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
- * that someone else started the grace period.
+ * that someone else started the grace period.  The caller must hold the
+ * ->lock of the leaf rcu_node structure corresponding to the current CPU,
+ *  and must have irqs disabled.
  */
+static void __note_new_gpnum(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
+{
+        if (rdp->gpnum != rnp->gpnum) {
+                rdp->qs_pending = 1;
+                rdp->passed_quiesc = 0;
+                rdp->gpnum = rnp->gpnum;
+        }
+}
+
 static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp)
 {
-        rdp->qs_pending = 1;
-        rdp->passed_quiesc = 0;
-        rdp->gpnum = rsp->gpnum;
+        unsigned long flags;
+        struct rcu_node *rnp;
+
+        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. */
+                local_irq_restore(flags);
+                return;
+        }
+        __note_new_gpnum(rsp, rnp, rdp);
+        spin_unlock_irqrestore(&rnp->lock, flags);
 }
 
 /*
@@ -583,6 +574,79 @@ check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp)
 }
 
 /*
+ * Advance this CPU's callbacks, but only if the current grace period
+ * has ended.  This may be called only from the CPU to whom the rdp
+ * belongs.  In addition, the corresponding leaf rcu_node structure's
+ * ->lock must be held by the caller, with irqs disabled.
+ */
+static void
+__rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
+{
+        /* Did another grace period end? */
+        if (rdp->completed != rnp->completed) {
+
+                /* Advance callbacks.  No harm if list empty. */
+                rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
+                rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
+                rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+
+                /* Remember that we saw this grace-period completion. */
+                rdp->completed = rnp->completed;
+        }
+}
+
+/*
+ * Advance this CPU's callbacks, but only if the current grace period
+ * has ended.  This may be called only from the CPU to whom the rdp
+ * belongs.
+ */
+static void
+rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
+{
+        unsigned long flags;
+        struct rcu_node *rnp;
+
+        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. */
+                local_irq_restore(flags);
+                return;
+        }
+        __rcu_process_gp_end(rsp, rnp, rdp);
+        spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+/*
+ * Do per-CPU grace-period initialization for running CPU.  The caller
+ * must hold the lock of the leaf rcu_node structure corresponding to
+ * this CPU.
+ */
+static void
+rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
+{
+        /* Prior grace period ended, so advance callbacks for current CPU. */
+        __rcu_process_gp_end(rsp, rnp, rdp);
+
+        /*
+         * Because this CPU just now started the new grace period, we know
+         * that all of its callbacks will be covered by this upcoming grace
+         * period, even the ones that were registered arbitrarily recently.
+         * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL.
+         *
+         * Other CPUs cannot be sure exactly when the grace period started.
+         * Therefore, their recently registered callbacks must pass through
+         * an additional RCU_NEXT_READY stage, so that they will be handled
+         * by the next RCU grace period.
+         */
+        rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+        rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+
+        /* Set state so that this CPU will detect the next quiescent state. */
+        __note_new_gpnum(rsp, rnp, rdp);
+}
+
+/*
  * Start a new RCU grace period if warranted, re-initializing the hierarchy
  * in preparation for detecting the next grace period.  The caller must hold
  * the root node's ->lock, which is released before return.  Hard irqs must
@@ -596,7 +660,23 @@ 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)) {
-                spin_unlock_irqrestore(&rnp->lock, flags);
+                if (rnp->completed == rsp->completed) {
+                        spin_unlock_irqrestore(&rnp->lock, flags);
+                        return;
+                }
+                spin_unlock(&rnp->lock);         /* irqs remain disabled. */
+
+                /*
+                 * Propagate new ->completed value to rcu_node structures
+                 * so that other CPUs don't have to wait until the start
+                 * of the next grace period to process their callbacks.
+                 */
+                rcu_for_each_node_breadth_first(rsp, rnp) {
+                        spin_lock(&rnp->lock);   /* irqs already disabled. */
+                        rnp->completed = rsp->completed;
+                        spin_unlock(&rnp->lock); /* irqs remain disabled. */
+                }
+                local_irq_restore(flags);
                 return;
         }
 
@@ -606,29 +686,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
         rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
         rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
         record_gp_stall_check_time(rsp);
-        dyntick_record_completed(rsp, rsp->completed - 1);
-        note_new_gpnum(rsp, rdp);
-
-        /*
-         * Because this CPU just now started the new grace period, we know
-         * that all of its callbacks will be covered by this upcoming grace
-         * period, even the ones that were registered arbitrarily recently.
-         * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL.
-         *
-         * Other CPUs cannot be sure exactly when the grace period started.
-         * Therefore, their recently registered callbacks must pass through
-         * an additional RCU_NEXT_READY stage, so that they will be handled
-         * by the next RCU grace period.
-         */
-        rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
-        rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
 
         /* Special-case the common single-level case. */
         if (NUM_RCU_NODES == 1) {
                 rcu_preempt_check_blocked_tasks(rnp);
                 rnp->qsmask = rnp->qsmaskinit;
                 rnp->gpnum = rsp->gpnum;
+                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);
                 return;
         }
@@ -657,69 +723,50 @@ 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. */
+                spin_lock(&rnp->lock);          /* irqs already disabled. */
                 rcu_preempt_check_blocked_tasks(rnp);
                 rnp->qsmask = rnp->qsmaskinit;
                 rnp->gpnum = rsp->gpnum;
-                spin_unlock(&rnp->lock);        /* irqs already disabled. */
+                rnp->completed = rsp->completed;
+                if (rnp == rdp->mynode)
+                        rcu_start_gp_per_cpu(rsp, rnp, rdp);
+                spin_unlock(&rnp->lock);        /* irqs remain disabled. */
         }
 
+        rnp = rcu_get_root(rsp);
+        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);
 }
 
 /*
- * Advance this CPU's callbacks, but only if the current grace period
- * has ended.  This may be called only from the CPU to whom the rdp
- * belongs.
- */
-static void
-rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
-{
-        long completed_snap;
-        unsigned long flags;
-
-        local_irq_save(flags);
-        completed_snap = ACCESS_ONCE(rsp->completed);  /* outside of lock. */
-
-        /* Did another grace period end? */
-        if (rdp->completed != completed_snap) {
-
-                /* Advance callbacks.  No harm if list empty. */
-                rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
-                rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
-                rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
-
-                /* Remember that we saw this grace-period completion. */
-                rdp->completed = completed_snap;
-        }
-        local_irq_restore(flags);
-}
-
-/*
- * Clean up after the prior grace period and let rcu_start_gp() start up
- * the next grace period if one is needed.  Note that the caller must
- * hold rnp->lock, as required by rcu_start_gp(), which will release it.
+ * Report a full set of quiescent states to the specified rcu_state
+ * data structure.  This involves cleaning up after the prior grace
+ * period and letting rcu_start_gp() start up the next grace period
+ * if one is needed.  Note that the caller must hold rnp->lock, as
+ * required by rcu_start_gp(), which will release it.
  */
-static void cpu_quiet_msk_finish(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)
 {
         WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
         rsp->completed = rsp->gpnum;
-        rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
+        rsp->signaled = RCU_GP_IDLE;
         rcu_start_gp(rsp, flags);  /* releases root node's rnp->lock. */
 }
 
 /*
- * Similar to cpu_quiet(), for which it is a helper function.  Allows
- * a group of CPUs to be quieted at one go, though all the CPUs in the
- * group must be represented by the same leaf rcu_node structure.
- * That structure's lock must be held upon entry, and it is released
- * before return.
+ * Similar to rcu_report_qs_rdp(), for which it is a helper function.
+ * Allows quiescent states for a group of CPUs to be reported at one go
+ * to the specified rcu_node structure, though all the CPUs in the group
+ * must be represented by the same rcu_node structure (which need not be
+ * a leaf rcu_node structure, though it often will be).  That structure's
+ * lock must be held upon entry, and it is released before return.
  */
 static void
-cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
-              unsigned long flags)
+rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
+                  struct rcu_node *rnp, unsigned long flags)
         __releases(rnp->lock)
 {
         struct rcu_node *rnp_c;
@@ -755,21 +802,23 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
 
         /*
          * Get here if we are the last CPU to pass through a quiescent
-         * state for this grace period.  Invoke cpu_quiet_msk_finish()
+         * state for this grace period.  Invoke rcu_report_qs_rsp()
          * to clean up and start the next grace period if one is needed.
          */
-        cpu_quiet_msk_finish(rsp, flags); /* releases rnp->lock. */
+        rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */
 }
 
 /*
- * Record a quiescent state for the specified CPU, which must either be
- * the current CPU.  The lastcomp argument is used to make sure we are
- * still in the grace period of interest.  We don't want to end the current
- * grace period based on quiescent states detected in an earlier grace
- * period!
+ * Record a quiescent state for the specified CPU to that CPU's rcu_data
+ * structure.  This must be either called from the specified CPU, or
+ * called when the specified CPU is known to be offline (and when it is
+ * also known that no other CPU is concurrently trying to help the offline
+ * CPU).  The lastcomp argument is used to make sure we are still in the
+ * grace period of interest.  We don't want to end the current grace period
+ * based on quiescent states detected in an earlier grace period!
  */
 static void
-cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
+rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
 {
         unsigned long flags;
         unsigned long mask;
@@ -777,15 +826,15 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
 
         rnp = rdp->mynode;
         spin_lock_irqsave(&rnp->lock, flags);
-        if (lastcomp != ACCESS_ONCE(rsp->completed)) {
+        if (lastcomp != rnp->completed) {
 
                 /*
                  * Someone beat us to it for this grace period, so leave.
                  * The race with GP start is resolved by the fact that we
                  * hold the leaf rcu_node lock, so that the per-CPU bits
                  * cannot yet be initialized -- so we would simply find our
-                 * CPU's bit already cleared in cpu_quiet_msk() if this race
-                 * occurred.
+                 * CPU's bit already cleared in rcu_report_qs_rnp() if this
+                 * race occurred.
                  */
                 rdp->passed_quiesc = 0; /* try again later! */
                 spin_unlock_irqrestore(&rnp->lock, flags);
@@ -803,7 +852,7 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
                  */
                 rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
 
-                cpu_quiet_msk(mask, rsp, rnp, flags); /* releases rnp->lock */
+                rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */
         }
 }
 
@@ -834,8 +883,11 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
         if (!rdp->passed_quiesc)
                 return;
 
-        /* Tell RCU we are done (but cpu_quiet() will be the judge of that). */
-        cpu_quiet(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
+        /*
+         * Tell RCU we are done (but rcu_report_qs_rdp() will be the
+         * judge of that).
+         */
+        rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -895,8 +947,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
 static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
 {
         unsigned long flags;
-        long lastcomp;
         unsigned long mask;
+        int need_report = 0;
         struct rcu_data *rdp = rsp->rda[cpu];
         struct rcu_node *rnp;
 
@@ -910,17 +962,32 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
                 spin_lock(&rnp->lock);          /* irqs already disabled. */
                 rnp->qsmaskinit &= ~mask;
                 if (rnp->qsmaskinit != 0) {
-                        spin_unlock(&rnp->lock); /* irqs remain disabled. */
+                        if (rnp != rdp->mynode)
+                                spin_unlock(&rnp->lock); /* irqs remain disabled. */
                         break;
                 }
-                rcu_preempt_offline_tasks(rsp, rnp, rdp);
+                if (rnp == rdp->mynode)
+                        need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
+                else
+                        spin_unlock(&rnp->lock); /* irqs remain disabled. */
                 mask = rnp->grpmask;
-                spin_unlock(&rnp->lock);        /* irqs remain disabled. */
                 rnp = rnp->parent;
         } while (rnp != NULL);
-        lastcomp = rsp->completed;
 
-        spin_unlock_irqrestore(&rsp->onofflock, flags);
+        /*
+         * We still hold the leaf rcu_node structure lock here, and
+         * irqs are still disabled.  The reason for this subterfuge is
+         * because invoking rcu_report_unblock_qs_rnp() with ->onofflock
+         * held leads to deadlock.
+         */
+        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);
+        if (need_report & RCU_OFL_TASKS_EXP_GP)
+                rcu_report_exp_rnp(rsp, rnp);
 
         rcu_adopt_orphan_cbs(rsp);
 }
@@ -958,7 +1025,7 @@ static void rcu_offline_cpu(int cpu)
  * Invoke any RCU callbacks that have made it to the end of their grace
  * period.  Thottle as specified by rdp->blimit.
  */
-static void rcu_do_batch(struct rcu_data *rdp)
+static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
 {
         unsigned long flags;
         struct rcu_head *next, *list, **tail;
@@ -1011,6 +1078,13 @@ static void rcu_do_batch(struct rcu_data *rdp)
         if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark)
                 rdp->blimit = blimit;
 
+        /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
+        if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) {
+                rdp->qlen_last_fqs_check = 0;
+                rdp->n_force_qs_snap = rsp->n_force_qs;
+        } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark)
+                rdp->qlen_last_fqs_check = rdp->qlen;
+
         local_irq_restore(flags);
 
         /* Re-raise the RCU softirq if there are callbacks remaining. */
@@ -1085,7 +1159,7 @@ 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 (rsp->completed != lastcomp) {
+                if (rnp->completed != lastcomp) {
                         spin_unlock_irqrestore(&rnp->lock, flags);
                         return 1;
                 }
@@ -1099,10 +1173,10 @@ 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 && rsp->completed == lastcomp) {
+                if (mask != 0 && rnp->completed == lastcomp) {
 
-                        /* cpu_quiet_msk() releases rnp->lock. */
-                        cpu_quiet_msk(mask, rsp, rnp, flags);
+                        /* rcu_report_qs_rnp() releases rnp->lock. */
+                        rcu_report_qs_rnp(mask, rsp, rnp, flags);
                         continue;
                 }
                 spin_unlock_irqrestore(&rnp->lock, flags);
@@ -1120,6 +1194,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
         long lastcomp;
         struct rcu_node *rnp = rcu_get_root(rsp);
         u8 signaled;
+        u8 forcenow;
 
         if (!rcu_gp_in_progress(rsp))
                 return;  /* No grace period in progress, nothing to force. */
@@ -1132,19 +1207,20 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
                 goto unlock_ret; /* no emergency and done recently. */
         rsp->n_force_qs++;
         spin_lock(&rnp->lock);
-        lastcomp = rsp->completed;
+        lastcomp = rsp->gpnum - 1;
         signaled = rsp->signaled;
         rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
-        if (lastcomp == rsp->gpnum) {
+        if(!rcu_gp_in_progress(rsp)) {
                 rsp->n_force_qs_ngp++;
                 spin_unlock(&rnp->lock);
                 goto unlock_ret;  /* no GP in progress, time updated. */
         }
         spin_unlock(&rnp->lock);
         switch (signaled) {
+        case RCU_GP_IDLE:
         case RCU_GP_INIT:
 
-                break; /* grace period still initializing, ignore. */
+                break; /* grace period idle or initializing, ignore. */
 
         case RCU_SAVE_DYNTICK:
 
@@ -1155,20 +1231,29 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
                 if (rcu_process_dyntick(rsp, lastcomp,
                                         dyntick_save_progress_counter))
                         goto unlock_ret;
+                /* fall into next case. */
+
+        case RCU_SAVE_COMPLETED:
 
                 /* Update state, record completion counter. */
+                forcenow = 0;
                 spin_lock(&rnp->lock);
-                if (lastcomp == rsp->completed) {
+                if (lastcomp + 1 == rsp->gpnum &&
+                    lastcomp == rsp->completed &&
+                    rsp->signaled == signaled) {
                         rsp->signaled = RCU_FORCE_QS;
-                        dyntick_record_completed(rsp, lastcomp);
+                        rsp->completed_fqs = lastcomp;
+                        forcenow = signaled == RCU_SAVE_COMPLETED;
                 }
                 spin_unlock(&rnp->lock);
-                break;
+                if (!forcenow)
+                        break;
+                /* fall into next case. */
 
         case RCU_FORCE_QS:
 
                 /* Check dyntick-idle state, send IPI to laggarts. */
-                if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),
+                if (rcu_process_dyntick(rsp, rsp->completed_fqs,
                                         rcu_implicit_dynticks_qs))
                         goto unlock_ret;
 
@@ -1224,7 +1309,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
         }
 
         /* If there are callbacks ready, invoke them. */
-        rcu_do_batch(rdp);
+        rcu_do_batch(rsp, rdp);
 }
 
 /*
@@ -1288,10 +1373,20 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
                 rcu_start_gp(rsp, nestflag);  /* releases rnp_root->lock. */
         }
 
-        /* Force the grace period if too many callbacks or too long waiting. */
-        if (unlikely(++rdp->qlen > qhimark)) {
+        /*
+         * Force the grace period if too many callbacks or too long waiting.
+         * Enforce hysteresis, and don't invoke force_quiescent_state()
+         * if some other CPU has recently done so.  Also, don't bother
+         * 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)) {
                 rdp->blimit = LONG_MAX;
-                force_quiescent_state(rsp, 0);
+                if (rsp->n_force_qs == rdp->n_force_qs_snap &&
+                    *rdp->nxttail[RCU_DONE_TAIL] != head)
+                        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)
                 force_quiescent_state(rsp, 1);
         local_irq_restore(flags);
@@ -1315,6 +1410,68 @@ void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
 }
 EXPORT_SYMBOL_GPL(call_rcu_bh);
 
+/**
+ * synchronize_sched - wait until an rcu-sched grace period has elapsed.
+ *
+ * Control will return to the caller some time after a full rcu-sched
+ * grace period has elapsed, in other words after all currently executing
+ * rcu-sched read-side critical sections have completed.   These read-side
+ * critical sections are delimited by rcu_read_lock_sched() and
+ * rcu_read_unlock_sched(), and may be nested.  Note that preempt_disable(),
+ * local_irq_disable(), and so on may be used in place of
+ * rcu_read_lock_sched().
+ *
+ * This means that all preempt_disable code sequences, including NMI and
+ * hardware-interrupt handlers, in progress on entry will have completed
+ * before this primitive returns.  However, this does not guarantee that
+ * softirq handlers will have completed, since in some kernels, these
+ * handlers can run in process context, and can block.
+ *
+ * This primitive provides the guarantees made by the (now removed)
+ * synchronize_kernel() API.  In contrast, synchronize_rcu() only
+ * guarantees that rcu_read_lock() sections will have completed.
+ * In "classic RCU", these two guarantees happen to be one and
+ * the same, but can differ in realtime RCU implementations.
+ */
+void synchronize_sched(void)
+{
+        struct rcu_synchronize rcu;
+
+        if (rcu_blocking_is_gp())
+                return;
+
+        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);
+}
+EXPORT_SYMBOL_GPL(synchronize_sched);
+
+/**
+ * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
+ *
+ * Control will return to the caller some time after a full rcu_bh grace
+ * period has elapsed, in other words after all currently executing rcu_bh
+ * read-side critical sections have completed.  RCU read-side critical
+ * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
+ * and may be nested.
+ */
+void synchronize_rcu_bh(void)
+{
+        struct rcu_synchronize rcu;
+
+        if (rcu_blocking_is_gp())
+                return;
+
+        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);
+}
+EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
+
 /*
  * Check to see if there is any immediate RCU-related work to be done
  * by the current CPU, for the specified type of RCU, returning 1 if so.
@@ -1324,6 +1481,8 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
  */
 static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
 {
+        struct rcu_node *rnp = rdp->mynode;
+
         rdp->n_rcu_pending++;
 
         /* Check for CPU stalls, if enabled. */
@@ -1348,13 +1507,13 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
         }
 
         /* Has another RCU grace period completed?  */
-        if (ACCESS_ONCE(rsp->completed) != rdp->completed) { /* outside lock */
+        if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
                 rdp->n_rp_gp_completed++;
                 return 1;
         }
 
         /* Has a new RCU grace period started? */
-        if (ACCESS_ONCE(rsp->gpnum) != rdp->gpnum) { /* outside lock */
+        if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */
                 rdp->n_rp_gp_started++;
                 return 1;
         }
@@ -1397,6 +1556,21 @@ 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);
@@ -1508,21 +1682,18 @@ static void __cpuinit
 rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
 {
         unsigned long flags;
-        long lastcomp;
         unsigned long mask;
         struct rcu_data *rdp = rsp->rda[cpu];
         struct rcu_node *rnp = rcu_get_root(rsp);
 
         /* Set up local state, ensuring consistent view of global state. */
         spin_lock_irqsave(&rnp->lock, flags);
-        lastcomp = rsp->completed;
-        rdp->completed = lastcomp;
-        rdp->gpnum = lastcomp;
         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->passed_quiesc_completed = lastcomp - 1;
+        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. */
 
@@ -1542,6 +1713,11 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
                 spin_lock(&rnp->lock);  /* irqs already disabled. */
                 rnp->qsmaskinit |= mask;
                 mask = rnp->grpmask;
+                if (rnp == rdp->mynode) {
+                        rdp->gpnum = rnp->completed; /* if GP in progress... */
+                        rdp->completed = rnp->completed;
+                        rdp->passed_quiesc_completed = rnp->completed - 1;
+                }
                 spin_unlock(&rnp->lock); /* irqs already disabled. */
                 rnp = rnp->parent;
         } while (rnp != NULL && !(rnp->qsmaskinit & mask));
@@ -1559,8 +1735,8 @@ static void __cpuinit rcu_online_cpu(int cpu)
 /*
  * Handle CPU online/offline notification events.
  */
-int __cpuinit rcu_cpu_notify(struct notifier_block *self,
-                             unsigned long action, void *hcpu)
+static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
+                                    unsigned long action, void *hcpu)
 {
         long cpu = (long)hcpu;
 
@@ -1647,8 +1823,8 @@ 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++) {
-                        if (rnp != rcu_get_root(rsp))
-                                spin_lock_init(&rnp->lock);
+                        spin_lock_init(&rnp->lock);
+                        lockdep_set_class(&rnp->lock, &rcu_node_class[i]);
                         rnp->gpnum = 0;
                         rnp->qsmask = 0;
                         rnp->qsmaskinit = 0;
@@ -1669,9 +1845,10 @@ static void __init rcu_init_one(struct rcu_state *rsp)
                         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]);
                 }
         }
-        spin_lock_init(&rcu_get_root(rsp)->lock);
 }
 
 /*
@@ -1697,16 +1874,30 @@ do { \
         } \
 } while (0)
 
-void __init __rcu_init(void)
+void __init rcu_init(void)
 {
+        int i;
+
         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();
         open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+
+        /*
+         * We don't need protection against CPU-hotplug here because
+         * this is called early in boot, before either interrupts
+         * 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);
 }
 
 #include "rcutree_plugin.h"