1 files changed, 69 insertions, 30 deletions

diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 0cf8146bd585..13458bbaa1be 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -47,15 +47,16 @@
 #include <linux/notifier.h>
 #include <linux/rcupdate.h>
 #include <linux/cpu.h>
+#include <linux/mutex.h>
 
 /* Definition for rcupdate control block. */
-struct rcu_ctrlblk rcu_ctrlblk = {
+static struct rcu_ctrlblk rcu_ctrlblk = {
         .cur = -300,
         .completed = -300,
         .lock = SPIN_LOCK_UNLOCKED,
         .cpumask = CPU_MASK_NONE,
 };
-struct rcu_ctrlblk rcu_bh_ctrlblk = {
+static struct rcu_ctrlblk rcu_bh_ctrlblk = {
         .cur = -300,
         .completed = -300,
         .lock = SPIN_LOCK_UNLOCKED,
@@ -67,7 +68,43 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L };
 
 /* Fake initialization required by compiler */
 static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL};
-static int maxbatch = 10000;
+static int blimit = 10;
+static int qhimark = 10000;
+static int qlowmark = 100;
+#ifdef CONFIG_SMP
+static int rsinterval = 1000;
+#endif
+
+static atomic_t rcu_barrier_cpu_count;
+static DEFINE_MUTEX(rcu_barrier_mutex);
+static struct completion rcu_barrier_completion;
+
+#ifdef CONFIG_SMP
+static void force_quiescent_state(struct rcu_data *rdp,
+                        struct rcu_ctrlblk *rcp)
+{
+        int cpu;
+        cpumask_t cpumask;
+        set_need_resched();
+        if (unlikely(rdp->qlen - rdp->last_rs_qlen > rsinterval)) {
+                rdp->last_rs_qlen = rdp->qlen;
+                /*
+                 * Don't send IPI to itself. With irqs disabled,
+                 * rdp->cpu is the current cpu.
+                 */
+                cpumask = rcp->cpumask;
+                cpu_clear(rdp->cpu, cpumask);
+                for_each_cpu_mask(cpu, cpumask)
+                        smp_send_reschedule(cpu);
+        }
+}
+#else
+static inline void force_quiescent_state(struct rcu_data *rdp,
+                        struct rcu_ctrlblk *rcp)
+{
+        set_need_resched();
+}
+#endif
 
 /**
  * call_rcu - Queue an RCU callback for invocation after a grace period.
@@ -92,17 +129,13 @@ void fastcall call_rcu(struct rcu_head *head,
         rdp = &__get_cpu_var(rcu_data);
         *rdp->nxttail = head;
         rdp->nxttail = &head->next;
-
-        if (unlikely(++rdp->count > 10000))
-                set_need_resched();
-
+        if (unlikely(++rdp->qlen > qhimark)) {
+                rdp->blimit = INT_MAX;
+                force_quiescent_state(rdp, &rcu_ctrlblk);
+        }
         local_irq_restore(flags);
 }
 
-static atomic_t rcu_barrier_cpu_count;
-static struct semaphore rcu_barrier_sema;
-static struct completion rcu_barrier_completion;
-
 /**
  * call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
  * @head: structure to be used for queueing the RCU updates.
@@ -131,12 +164,12 @@ void fastcall call_rcu_bh(struct rcu_head *head,
         rdp = &__get_cpu_var(rcu_bh_data);
         *rdp->nxttail = head;
         rdp->nxttail = &head->next;
-        rdp->count++;
-/*
- *  Should we directly call rcu_do_batch() here ?
- *  if (unlikely(rdp->count > 10000))
- *      rcu_do_batch(rdp);
- */
+
+        if (unlikely(++rdp->qlen > qhimark)) {
+                rdp->blimit = INT_MAX;
+                force_quiescent_state(rdp, &rcu_bh_ctrlblk);
+        }
+
         local_irq_restore(flags);
 }
 
@@ -175,13 +208,13 @@ static void rcu_barrier_func(void *notused)
 void rcu_barrier(void)
 {
         BUG_ON(in_interrupt());
-        /* Take cpucontrol semaphore to protect against CPU hotplug */
-        down(&rcu_barrier_sema);
+        /* Take cpucontrol mutex to protect against CPU hotplug */
+        mutex_lock(&rcu_barrier_mutex);
         init_completion(&rcu_barrier_completion);
         atomic_set(&rcu_barrier_cpu_count, 0);
         on_each_cpu(rcu_barrier_func, NULL, 0, 1);
         wait_for_completion(&rcu_barrier_completion);
-        up(&rcu_barrier_sema);
+        mutex_unlock(&rcu_barrier_mutex);
 }
 EXPORT_SYMBOL_GPL(rcu_barrier);
 
@@ -199,10 +232,12 @@ static void rcu_do_batch(struct rcu_data *rdp)
                 next = rdp->donelist = list->next;
                 list->func(list);
                 list = next;
-                rdp->count--;
-                if (++count >= maxbatch)
+                rdp->qlen--;
+                if (++count >= rdp->blimit)
                         break;
         }
+        if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark)
+                rdp->blimit = blimit;
         if (!rdp->donelist)
                 rdp->donetail = &rdp->donelist;
         else
@@ -381,8 +416,8 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
                 rdp->curtail = &rdp->curlist;
         }
 
-        local_irq_disable();
         if (rdp->nxtlist && !rdp->curlist) {
+                local_irq_disable();
                 rdp->curlist = rdp->nxtlist;
                 rdp->curtail = rdp->nxttail;
                 rdp->nxtlist = NULL;
@@ -407,9 +442,8 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
                         rcu_start_batch(rcp);
                         spin_unlock(&rcp->lock);
                 }
-        } else {
-                local_irq_enable();
         }
+
         rcu_check_quiescent_state(rcp, rdp);
         if (rdp->donelist)
                 rcu_do_batch(rdp);
@@ -473,6 +507,7 @@ static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp,
         rdp->quiescbatch = rcp->completed;
         rdp->qs_pending = 0;
         rdp->cpu = cpu;
+        rdp->blimit = blimit;
 }
 
 static void __devinit rcu_online_cpu(int cpu)
@@ -514,7 +549,6 @@ static struct notifier_block __devinitdata rcu_nb = {
  */
 void __init rcu_init(void)
 {
-        sema_init(&rcu_barrier_sema, 1);
         rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE,
                         (void *)(long)smp_processor_id());
         /* Register notifier for non-boot CPUs */
@@ -567,9 +601,14 @@ void synchronize_kernel(void)
         synchronize_rcu();
 }
 
-module_param(maxbatch, int, 0);
+module_param(blimit, int, 0);
+module_param(qhimark, int, 0);
+module_param(qlowmark, int, 0);
+#ifdef CONFIG_SMP
+module_param(rsinterval, int, 0);
+#endif
 EXPORT_SYMBOL_GPL(rcu_batches_completed);
-EXPORT_SYMBOL(call_rcu);  /* WARNING: GPL-only in April 2006. */
-EXPORT_SYMBOL(call_rcu_bh);  /* WARNING: GPL-only in April 2006. */
+EXPORT_SYMBOL_GPL_FUTURE(call_rcu);     /* WARNING: GPL-only in April 2006. */
+EXPORT_SYMBOL_GPL_FUTURE(call_rcu_bh);  /* WARNING: GPL-only in April 2006. */
 EXPORT_SYMBOL_GPL(synchronize_rcu);
-EXPORT_SYMBOL(synchronize_kernel);  /* WARNING: GPL-only in April 2006. */
+EXPORT_SYMBOL_GPL_FUTURE(synchronize_kernel); /* WARNING: GPL-only in April 2006. */