diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index f280e542e3e9f..f08ee3bc5741b 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -139,7 +139,7 @@ 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 rcu_boost_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);
@@ -1469,7 +1469,7 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
/* Adjust any no-longer-needed kthreads. */
rcu_stop_cpu_kthread(cpu);
- rcu_node_kthread_setaffinity(rnp, -1);
+ rcu_boost_kthread_setaffinity(rnp, -1);
/* Remove the dead CPU from the bitmasks in the rcu_node hierarchy. */
@@ -2594,11 +2594,11 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
break;
case CPU_ONLINE:
case CPU_DOWN_FAILED:
- rcu_node_kthread_setaffinity(rnp, -1);
+ rcu_boost_kthread_setaffinity(rnp, -1);
rcu_cpu_kthread_setrt(cpu, 1);
break;
case CPU_DOWN_PREPARE:
- rcu_node_kthread_setaffinity(rnp, cpu);
+ rcu_boost_kthread_setaffinity(rnp, cpu);
rcu_cpu_kthread_setrt(cpu, 0);
break;
case CPU_DYING:
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 4d29169f21246..f08176172546f 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -491,13 +491,8 @@ static void invoke_rcu_callbacks_kthread(void);
static bool rcu_is_callbacks_kthread(void);
#ifdef CONFIG_RCU_BOOST
static void rcu_preempt_do_callbacks(void);
-static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
- cpumask_var_t cm);
static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
- struct rcu_node *rnp,
- int rnp_index);
-static void invoke_rcu_node_kthread(struct rcu_node *rnp);
-static void rcu_yield(void (*f)(unsigned long), unsigned long arg);
+ struct rcu_node *rnp);
#endif /* #ifdef CONFIG_RCU_BOOST */
static void rcu_cpu_kthread_setrt(int cpu, int to_rt);
static void __cpuinit rcu_prepare_kthreads(int cpu);
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 7f3244c0df014..0f8b5ec64a7d7 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1069,6 +1069,16 @@ static void rcu_initiate_boost_trace(struct rcu_node *rnp)
#endif /* #else #ifdef CONFIG_RCU_TRACE */
+static void rcu_wake_cond(struct task_struct *t, int status)
+{
+ /*
+ * If the thread is yielding, only wake it when this
+ * is invoked from idle
+ */
+ if (status != RCU_KTHREAD_YIELDING || is_idle_task(current))
+ wake_up_process(t);
+}
+
/*
* Carry out RCU priority boosting on the task indicated by ->exp_tasks
* or ->boost_tasks, advancing the pointer to the next task in the
@@ -1140,17 +1150,6 @@ static int rcu_boost(struct rcu_node *rnp)
ACCESS_ONCE(rnp->boost_tasks) != NULL;
}
-/*
- * Timer handler to initiate waking up of boost kthreads that
- * have yielded the CPU due to excessive numbers of tasks to
- * boost. We wake up the per-rcu_node kthread, which in turn
- * will wake up the booster kthread.
- */
-static void rcu_boost_kthread_timer(unsigned long arg)
-{
- invoke_rcu_node_kthread((struct rcu_node *)arg);
-}
-
/*
* Priority-boosting kthread. One per leaf rcu_node and one for the
* root rcu_node.
@@ -1174,8 +1173,9 @@ static int rcu_boost_kthread(void *arg)
else
spincnt = 0;
if (spincnt > 10) {
+ rnp->boost_kthread_status = RCU_KTHREAD_YIELDING;
trace_rcu_utilization("End boost kthread@rcu_yield");
- rcu_yield(rcu_boost_kthread_timer, (unsigned long)rnp);
+ schedule_timeout_interruptible(2);
trace_rcu_utilization("Start boost kthread@rcu_yield");
spincnt = 0;
}
@@ -1213,8 +1213,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
rnp->boost_tasks = rnp->gp_tasks;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
t = rnp->boost_kthread_task;
- if (t != NULL)
- wake_up_process(t);
+ if (t)
+ rcu_wake_cond(t, rnp->boost_kthread_status);
} else {
rcu_initiate_boost_trace(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
@@ -1231,8 +1231,10 @@ static void invoke_rcu_callbacks_kthread(void)
local_irq_save(flags);
__this_cpu_write(rcu_cpu_has_work, 1);
if (__this_cpu_read(rcu_cpu_kthread_task) != NULL &&
- current != __this_cpu_read(rcu_cpu_kthread_task))
- wake_up_process(__this_cpu_read(rcu_cpu_kthread_task));
+ current != __this_cpu_read(rcu_cpu_kthread_task)) {
+ rcu_wake_cond(__this_cpu_read(rcu_cpu_kthread_task),
+ __this_cpu_read(rcu_cpu_kthread_status));
+ }
local_irq_restore(flags);
}
@@ -1245,21 +1247,6 @@ static bool rcu_is_callbacks_kthread(void)
return __get_cpu_var(rcu_cpu_kthread_task) == current;
}
-/*
- * Set the affinity of the boost kthread. The CPU-hotplug locks are
- * held, so no one should be messing with the existence of the boost
- * kthread.
- */
-static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
- cpumask_var_t cm)
-{
- struct task_struct *t;
-
- t = rnp->boost_kthread_task;
- if (t != NULL)
- set_cpus_allowed_ptr(rnp->boost_kthread_task, cm);
-}
-
#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000)
/*
@@ -1276,15 +1263,19 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
* Returns zero if all is well, a negated errno otherwise.
*/
static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
- struct rcu_node *rnp,
- int rnp_index)
+ struct rcu_node *rnp)
{
+ int rnp_index = rnp - &rsp->node[0];
unsigned long flags;
struct sched_param sp;
struct task_struct *t;
if (&rcu_preempt_state != rsp)
return 0;
+
+ if (!rcu_scheduler_fully_active || rnp->qsmaskinit == 0)
+ return 0;
+
rsp->boost = 1;
if (rnp->boost_kthread_task != NULL)
return 0;
@@ -1327,20 +1318,6 @@ static void rcu_kthread_do_work(void)
rcu_preempt_do_callbacks();
}
-/*
- * Wake up the specified per-rcu_node-structure kthread.
- * Because the per-rcu_node kthreads are immortal, we don't need
- * to do anything to keep them alive.
- */
-static void invoke_rcu_node_kthread(struct rcu_node *rnp)
-{
- struct task_struct *t;
-
- t = rnp->node_kthread_task;
- if (t != NULL)
- wake_up_process(t);
-}
-
/*
* Set the specified CPU's kthread to run RT or not, as specified by
* the to_rt argument. The CPU-hotplug locks are held, so the task
@@ -1365,45 +1342,6 @@ static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
sched_setscheduler_nocheck(t, policy, &sp);
}
-/*
- * Timer handler to initiate the waking up of per-CPU kthreads that
- * have yielded the CPU due to excess numbers of RCU callbacks.
- * We wake up the per-rcu_node kthread, which in turn will wake up
- * the booster kthread.
- */
-static void rcu_cpu_kthread_timer(unsigned long arg)
-{
- struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg);
- struct rcu_node *rnp = rdp->mynode;
-
- atomic_or(rdp->grpmask, &rnp->wakemask);
- invoke_rcu_node_kthread(rnp);
-}
-
-/*
- * Drop to non-real-time priority and yield, but only after posting a
- * timer that will cause us to regain our real-time priority if we
- * remain preempted. Either way, we restore our real-time priority
- * before returning.
- */
-static void rcu_yield(void (*f)(unsigned long), unsigned long arg)
-{
- struct sched_param sp;
- struct timer_list yield_timer;
- int prio = current->rt_priority;
-
- setup_timer_on_stack(&yield_timer, f, arg);
- mod_timer(&yield_timer, jiffies + 2);
- sp.sched_priority = 0;
- sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp);
- set_user_nice(current, 19);
- schedule();
- set_user_nice(current, 0);
- sp.sched_priority = prio;
- sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
- del_timer(&yield_timer);
-}
-
/*
* Handle cases where the rcu_cpu_kthread() ends up on the wrong CPU.
* This can happen while the corresponding CPU is either coming online
@@ -1476,7 +1414,7 @@ static int rcu_cpu_kthread(void *arg)
if (spincnt > 10) {
*statusp = RCU_KTHREAD_YIELDING;
trace_rcu_utilization("End CPU kthread@rcu_yield");
- rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
+ schedule_timeout_interruptible(2);
trace_rcu_utilization("Start CPU kthread@rcu_yield");
spincnt = 0;
}
@@ -1532,48 +1470,6 @@ static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu)
return 0;
}
-/*
- * Per-rcu_node kthread, which is in charge of waking up the per-CPU
- * kthreads when needed. We ignore requests to wake up kthreads
- * for offline CPUs, which is OK because force_quiescent_state()
- * takes care of this case.
- */
-static int rcu_node_kthread(void *arg)
-{
- int cpu;
- unsigned long flags;
- unsigned long mask;
- struct rcu_node *rnp = (struct rcu_node *)arg;
- struct sched_param sp;
- struct task_struct *t;
-
- for (;;) {
- rnp->node_kthread_status = RCU_KTHREAD_WAITING;
- rcu_wait(atomic_read(&rnp->wakemask) != 0);
- rnp->node_kthread_status = RCU_KTHREAD_RUNNING;
- raw_spin_lock_irqsave(&rnp->lock, flags);
- mask = atomic_xchg(&rnp->wakemask, 0);
- rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
- for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) {
- if ((mask & 0x1) == 0)
- continue;
- preempt_disable();
- t = per_cpu(rcu_cpu_kthread_task, cpu);
- if (!cpu_online(cpu) || t == NULL) {
- preempt_enable();
- continue;
- }
- per_cpu(rcu_cpu_has_work, cpu) = 1;
- sp.sched_priority = RCU_KTHREAD_PRIO;
- sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
- preempt_enable();
- }
- }
- /* NOTREACHED */
- rnp->node_kthread_status = RCU_KTHREAD_STOPPED;
- return 0;
-}
-
/*
* Set the per-rcu_node kthread's affinity to cover all CPUs that are
* served by the rcu_node in question. The CPU hotplug lock is still
@@ -1583,17 +1479,17 @@ static int rcu_node_kthread(void *arg)
* no outgoing CPU. If there are no CPUs left in the affinity set,
* this function allows the kthread to execute on any CPU.
*/
-static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
+static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
{
+ struct task_struct *t = rnp->boost_kthread_task;
+ unsigned long mask = rnp->qsmaskinit;
cpumask_var_t cm;
int cpu;
- unsigned long mask = rnp->qsmaskinit;
- if (rnp->node_kthread_task == NULL)
+ if (!t)
return;
- if (!alloc_cpumask_var(&cm, GFP_KERNEL))
+ if (!zalloc_cpumask_var(&cm, GFP_KERNEL))
return;
- cpumask_clear(cm);
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
if ((mask & 0x1) && cpu != outgoingcpu)
cpumask_set_cpu(cpu, cm);
@@ -1603,50 +1499,17 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
cpumask_clear_cpu(cpu, cm);
WARN_ON_ONCE(cpumask_weight(cm) == 0);
}
- set_cpus_allowed_ptr(rnp->node_kthread_task, cm);
- rcu_boost_kthread_setaffinity(rnp, cm);
+ set_cpus_allowed_ptr(t, cm);
free_cpumask_var(cm);
}
-/*
- * Spawn a per-rcu_node kthread, setting priority and affinity.
- * Called during boot before online/offline can happen, or, if
- * during runtime, with the main CPU-hotplug locks held. So only
- * one of these can be executing at a time.
- */
-static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp,
- struct rcu_node *rnp)
-{
- unsigned long flags;
- int rnp_index = rnp - &rsp->node[0];
- struct sched_param sp;
- struct task_struct *t;
-
- if (!rcu_scheduler_fully_active ||
- rnp->qsmaskinit == 0)
- return 0;
- if (rnp->node_kthread_task == NULL) {
- t = kthread_create(rcu_node_kthread, (void *)rnp,
- "rcun/%d", rnp_index);
- if (IS_ERR(t))
- return PTR_ERR(t);
- raw_spin_lock_irqsave(&rnp->lock, flags);
- rnp->node_kthread_task = t;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
- sp.sched_priority = 99;
- sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
- wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */
- }
- return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index);
-}
-
/*
* Spawn all kthreads -- called as soon as the scheduler is running.
*/
static int __init rcu_spawn_kthreads(void)
{
- int cpu;
struct rcu_node *rnp;
+ int cpu;
rcu_scheduler_fully_active = 1;
for_each_possible_cpu(cpu) {
@@ -1655,10 +1518,10 @@ static int __init rcu_spawn_kthreads(void)
(void)rcu_spawn_one_cpu_kthread(cpu);
}
rnp = rcu_get_root(rcu_state);
- (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
+ (void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
if (NUM_RCU_NODES > 1) {
rcu_for_each_leaf_node(rcu_state, rnp)
- (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
+ (void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
}
return 0;
}
@@ -1672,8 +1535,7 @@ static void __cpuinit rcu_prepare_kthreads(int cpu)
/* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
if (rcu_scheduler_fully_active) {
(void)rcu_spawn_one_cpu_kthread(cpu);
- if (rnp->node_kthread_task == NULL)
- (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
+ (void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
}
}
@@ -1706,7 +1568,7 @@ static void rcu_stop_cpu_kthread(int cpu)
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
-static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
+static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
{
}