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;
+
int rcu_scheduler_active __read_mostly;
EXPORT_SYMBOL_GPL(rcu_scheduler_active);
static char rcu_kthreads_spawnable;
static void rcu_node_kthread_setaffinity(struct rcu_node *rnp);
-static void invoke_rcu_kthread(void);
+static void invoke_rcu_cpu_kthread(void);
#define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */
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;
}
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. */
}
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);
t = rnp->node_kthread_task;
if (t != NULL &&
rnp->qsmaskinit == 0) {
- kthread_stop(t);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
rnp->node_kthread_task = NULL;
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ kthread_stop(t);
+ rcu_stop_boost_kthread(rnp);
} else
rcu_node_kthread_setaffinity(rnp);
}
/* Re-raise the RCU softirq if there are callbacks remaining. */
if (cpu_has_callbacks_ready_to_invoke(rdp))
- invoke_rcu_kthread();
+ invoke_rcu_cpu_kthread();
}
/*
}
rcu_preempt_check_callbacks(cpu);
if (rcu_pending(cpu))
- invoke_rcu_kthread();
+ invoke_rcu_cpu_kthread();
}
#ifdef CONFIG_SMP
/*
* 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 *))
return;
}
if (rnp->qsmask == 0) {
+ rcu_initiate_boost(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
continue;
}
}
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
+ rnp = rcu_get_root(rsp);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ if (rnp->qsmask == 0)
+ rcu_initiate_boost(rnp);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/*
* the current CPU with interrupts disabled, the rcu_cpu_kthread_task
* cannot disappear out from under us.
*/
-static void invoke_rcu_kthread(void)
+static void invoke_rcu_cpu_kthread(void)
{
unsigned long flags;
wait_queue_head_t *q;
}
/*
+ * Wake up the specified per-rcu_node-structure kthread.
+ * The caller must hold ->lock.
+ */
+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);
+}
+
+/*
* 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)
{
unsigned long flags;
- struct rcu_data *rdp = (struct rcu_data *)arg;
+ struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg);
struct rcu_node *rnp = rdp->mynode;
- struct task_struct *t;
raw_spin_lock_irqsave(&rnp->lock, flags);
rnp->wakemask |= rdp->grpmask;
- t = rnp->node_kthread_task;
- if (t == NULL) {
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
- return;
- }
- wake_up_process(t);
+ invoke_rcu_node_kthread(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
* remain preempted. Either way, we restore our real-time priority
* before returning.
*/
-static void rcu_yield(int cpu)
+static void rcu_yield(void (*f)(unsigned long), unsigned long arg)
{
- struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu);
struct sched_param sp;
struct timer_list yield_timer;
- setup_timer_on_stack(&yield_timer, rcu_cpu_kthread_timer, (unsigned long)rdp);
+ 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);
else
spincnt = 0;
if (spincnt > 10) {
- rcu_yield(cpu);
+ rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
spincnt = 0;
}
}
raw_spin_lock_irqsave(&rnp->lock, flags);
mask = rnp->wakemask;
rnp->wakemask = 0;
+ rcu_initiate_boost(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) {
if ((mask & 0x1) == 0)
/*
* Set the per-rcu_node kthread's affinity to cover all CPUs that are
- * served by the rcu_node in question.
+ * served by the rcu_node in question. The CPU hotplug lock is still
+ * held, so the value of rnp->qsmaskinit will be stable.
*/
static void rcu_node_kthread_setaffinity(struct rcu_node *rnp)
{
int cpu;
unsigned long mask = rnp->qsmaskinit;
- if (rnp->node_kthread_task == NULL ||
- rnp->qsmaskinit == 0)
+ if (rnp->node_kthread_task == NULL || mask == 0)
return;
if (!alloc_cpumask_var(&cm, GFP_KERNEL))
return;
if (mask & 0x1)
cpumask_set_cpu(cpu, cm);
set_cpus_allowed_ptr(rnp->node_kthread_task, cm);
+ rcu_boost_kthread_setaffinity(rnp, 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_kthreads_spawnable ||
- rnp->qsmaskinit == 0 ||
- rnp->node_kthread_task != NULL)
+ rnp->qsmaskinit == 0)
return 0;
- t = kthread_create(rcu_node_kthread, (void *)rnp, "rcun%d", rnp_index);
- if (IS_ERR(t))
- return PTR_ERR(t);
- rnp->node_kthread_task = t;
- wake_up_process(t);
- sp.sched_priority = 99;
- sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
- 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);
+ wake_up_process(t);
+ sp.sched_priority = 99;
+ sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
+ }
+ return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index);
}
/*
if (cpu_online(cpu))
(void)rcu_spawn_one_cpu_kthread(cpu);
}
- rcu_for_each_leaf_node(&rcu_sched_state, rnp) {
- init_waitqueue_head(&rnp->node_wq);
- (void)rcu_spawn_one_node_kthread(&rcu_sched_state, rnp);
- }
+ rnp = rcu_get_root(rcu_state);
+ init_waitqueue_head(&rnp->node_wq);
+ rcu_init_boost_waitqueue(rnp);
+ (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
+ if (NUM_RCU_NODES > 1)
+ rcu_for_each_leaf_node(rcu_state, rnp) {
+ init_waitqueue_head(&rnp->node_wq);
+ rcu_init_boost_waitqueue(rnp);
+ (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
+ }
return 0;
}
early_initcall(rcu_spawn_kthreads);
static void __cpuinit rcu_online_kthreads(int cpu)
{
- struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu);
+ struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
struct rcu_node *rnp = rdp->mynode;
/* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
if (rcu_kthreads_spawnable) {
(void)rcu_spawn_one_cpu_kthread(cpu);
if (rnp->node_kthread_task == NULL)
- (void)rcu_spawn_one_node_kthread(&rcu_sched_state, rnp);
+ (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
}
}
unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
- struct rcu_data *rdp = per_cpu_ptr(rcu_sched_state.rda, cpu);
+ struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
struct rcu_node *rnp = rdp->mynode;
switch (action) {
struct rcu_state rcu_preempt_state = RCU_STATE_INITIALIZER(rcu_preempt_state);
DEFINE_PER_CPU(struct rcu_data, rcu_preempt_data);
+static struct rcu_state *rcu_state = &rcu_preempt_state;
static int rcu_preempted_readers_exp(struct rcu_node *rnp);
if ((rnp->qsmask & rdp->grpmask) && rnp->gp_tasks != NULL) {
list_add(&t->rcu_node_entry, rnp->gp_tasks->prev);
rnp->gp_tasks = &t->rcu_node_entry;
+#ifdef CONFIG_RCU_BOOST
+ if (rnp->boost_tasks != NULL)
+ rnp->boost_tasks = rnp->gp_tasks;
+#endif /* #ifdef CONFIG_RCU_BOOST */
} else {
list_add(&t->rcu_node_entry, &rnp->blkd_tasks);
if (rnp->qsmask & rdp->grpmask)
* for the specified rcu_node structure. If the caller needs a reliable
* answer, it must hold the rcu_node's ->lock.
*/
-static int rcu_preempted_readers(struct rcu_node *rnp)
+static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp)
{
return rnp->gp_tasks != NULL;
}
unsigned long mask;
struct rcu_node *rnp_p;
- if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) {
+ if (rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return; /* Still need more quiescent states! */
}
break;
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
- empty = !rcu_preempted_readers(rnp);
+ empty = !rcu_preempt_blocked_readers_cgp(rnp);
empty_exp = !rcu_preempted_readers_exp(rnp);
smp_mb(); /* ensure expedited fastpath sees end of RCU c-s. */
np = rcu_next_node_entry(t, rnp);
rnp->gp_tasks = np;
if (&t->rcu_node_entry == rnp->exp_tasks)
rnp->exp_tasks = np;
+#ifdef CONFIG_RCU_BOOST
+ if (&t->rcu_node_entry == rnp->boost_tasks)
+ rnp->boost_tasks = np;
+#endif /* #ifdef CONFIG_RCU_BOOST */
t->rcu_blocked_node = NULL;
/*
else
rcu_report_unblock_qs_rnp(rnp, flags);
+#ifdef CONFIG_RCU_BOOST
+ /* Unboost if we were boosted. */
+ if (special & RCU_READ_UNLOCK_BOOSTED) {
+ t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_BOOSTED;
+ rt_mutex_unlock(t->rcu_boost_mutex);
+ t->rcu_boost_mutex = NULL;
+ }
+#endif /* #ifdef CONFIG_RCU_BOOST */
+
/*
* If this was the last task on the expedited lists,
* then we need to report up the rcu_node hierarchy.
unsigned long flags;
struct task_struct *t;
- if (!rcu_preempted_readers(rnp))
+ if (!rcu_preempt_blocked_readers_cgp(rnp))
return;
raw_spin_lock_irqsave(&rnp->lock, flags);
t = list_entry(rnp->gp_tasks,
{
struct task_struct *t;
- if (!rcu_preempted_readers(rnp))
+ if (!rcu_preempt_blocked_readers_cgp(rnp))
return;
t = list_entry(rnp->gp_tasks,
struct task_struct, rcu_node_entry);
*/
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp)
{
- WARN_ON_ONCE(rcu_preempted_readers(rnp));
+ WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
if (!list_empty(&rnp->blkd_tasks))
rnp->gp_tasks = rnp->blkd_tasks.next;
WARN_ON_ONCE(rnp->qsmask);
* absolutely necessary, but this is a good performance/complexity
* tradeoff.
*/
- if (rcu_preempted_readers(rnp))
+ if (rcu_preempt_blocked_readers_cgp(rnp))
retval |= RCU_OFL_TASKS_NORM_GP;
if (rcu_preempted_readers_exp(rnp))
retval |= RCU_OFL_TASKS_EXP_GP;
rnp_root->gp_tasks = rnp->gp_tasks;
if (&t->rcu_node_entry == rnp->exp_tasks)
rnp_root->exp_tasks = rnp->exp_tasks;
+#ifdef CONFIG_RCU_BOOST
+ if (&t->rcu_node_entry == rnp->boost_tasks)
+ rnp_root->boost_tasks = rnp->boost_tasks;
+#endif /* #ifdef CONFIG_RCU_BOOST */
raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
}
+
+#ifdef CONFIG_RCU_BOOST
+ /* In case root is being boosted and leaf is not. */
+ raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
+ if (rnp_root->boost_tasks != NULL &&
+ rnp_root->boost_tasks != rnp_root->gp_tasks)
+ rnp_root->boost_tasks = rnp_root->gp_tasks;
+ raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
+#endif /* #ifdef CONFIG_RCU_BOOST */
+
rnp->gp_tasks = NULL;
rnp->exp_tasks = NULL;
return retval;
raw_spin_lock(&rnp->lock); /* irqs already disabled */
if (!list_empty(&rnp->blkd_tasks)) {
rnp->exp_tasks = rnp->blkd_tasks.next;
+ rcu_initiate_boost(rnp);
must_wait = 1;
}
raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
+static struct rcu_state *rcu_state = &rcu_sched_state;
+
/*
* Tell them what RCU they are running.
*/
* Because preemptable RCU does not exist, there are never any preempted
* RCU readers.
*/
-static int rcu_preempted_readers(struct rcu_node *rnp)
+static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp)
{
return 0;
}
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
+#ifdef CONFIG_RCU_BOOST
+
+#include "rtmutex_common.h"
+
+/*
+ * Carry out RCU priority boosting on the task indicated by ->exp_tasks
+ * or ->boost_tasks, advancing the pointer to the next task in the
+ * ->blkd_tasks list.
+ *
+ * Note that irqs must be enabled: boosting the task can block.
+ * Returns 1 if there are more tasks needing to be boosted.
+ */
+static int rcu_boost(struct rcu_node *rnp)
+{
+ unsigned long flags;
+ struct rt_mutex mtx;
+ struct task_struct *t;
+ struct list_head *tb;
+
+ if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL)
+ return 0; /* Nothing left to boost. */
+
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+
+ /*
+ * Recheck under the lock: all tasks in need of boosting
+ * might exit their RCU read-side critical sections on their own.
+ */
+ if (rnp->exp_tasks == NULL && rnp->boost_tasks == NULL) {
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ return 0;
+ }
+
+ /*
+ * Preferentially boost tasks blocking expedited grace periods.
+ * This cannot starve the normal grace periods because a second
+ * expedited grace period must boost all blocked tasks, including
+ * those blocking the pre-existing normal grace period.
+ */
+ if (rnp->exp_tasks != NULL)
+ tb = rnp->exp_tasks;
+ else
+ tb = rnp->boost_tasks;
+
+ /*
+ * We boost task t by manufacturing an rt_mutex that appears to
+ * be held by task t. We leave a pointer to that rt_mutex where
+ * task t can find it, and task t will release the mutex when it
+ * exits its outermost RCU read-side critical section. Then
+ * simply acquiring this artificial rt_mutex will boost task
+ * t's priority. (Thanks to tglx for suggesting this approach!)
+ *
+ * Note that task t must acquire rnp->lock to remove itself from
+ * the ->blkd_tasks list, which it will do from exit() if from
+ * nowhere else. We therefore are guaranteed that task t will
+ * stay around at least until we drop rnp->lock. Note that
+ * rnp->lock also resolves races between our priority boosting
+ * and task t's exiting its outermost RCU read-side critical
+ * section.
+ */
+ t = container_of(tb, struct task_struct, rcu_node_entry);
+ rt_mutex_init_proxy_locked(&mtx, t);
+ t->rcu_boost_mutex = &mtx;
+ t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BOOSTED;
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ rt_mutex_lock(&mtx); /* Side effect: boosts task t's priority. */
+ rt_mutex_unlock(&mtx); /* Keep lockdep happy. */
+
+ return rnp->exp_tasks != NULL || 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)
+{
+ unsigned long flags;
+ struct rcu_node *rnp = (struct rcu_node *)arg;
+
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ invoke_rcu_node_kthread(rnp);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+/*
+ * Priority-boosting kthread. One per leaf rcu_node and one for the
+ * root rcu_node.
+ */
+static int rcu_boost_kthread(void *arg)
+{
+ struct rcu_node *rnp = (struct rcu_node *)arg;
+ int spincnt = 0;
+ int more2boost;
+
+ for (;;) {
+ wait_event_interruptible(rnp->boost_wq, rnp->boost_tasks ||
+ rnp->exp_tasks ||
+ kthread_should_stop());
+ if (kthread_should_stop())
+ break;
+ more2boost = rcu_boost(rnp);
+ if (more2boost)
+ spincnt++;
+ else
+ spincnt = 0;
+ if (spincnt > 10) {
+ rcu_yield(rcu_boost_kthread_timer, (unsigned long)rnp);
+ spincnt = 0;
+ }
+ }
+ return 0;
+}
+
+/*
+ * Check to see if it is time to start boosting RCU readers that are
+ * blocking the current grace period, and, if so, tell the per-rcu_node
+ * kthread to start boosting them. If there is an expedited grace
+ * period in progress, it is always time to boost.
+ *
+ * The caller must hold rnp->lock.
+ */
+static void rcu_initiate_boost(struct rcu_node *rnp)
+{
+ struct task_struct *t;
+
+ if (!rcu_preempt_blocked_readers_cgp(rnp) && rnp->exp_tasks == NULL)
+ return;
+ if (rnp->exp_tasks != NULL ||
+ (rnp->gp_tasks != NULL &&
+ rnp->boost_tasks == NULL &&
+ rnp->qsmask == 0 &&
+ ULONG_CMP_GE(jiffies, rnp->boost_time))) {
+ if (rnp->exp_tasks == NULL)
+ rnp->boost_tasks = rnp->gp_tasks;
+ t = rnp->boost_kthread_task;
+ if (t != NULL)
+ wake_up_process(t);
+ }
+}
+
+static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
+ cpumask_var_t cm)
+{
+ unsigned long flags;
+ struct task_struct *t;
+
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ t = rnp->boost_kthread_task;
+ if (t != NULL)
+ set_cpus_allowed_ptr(rnp->boost_kthread_task, cm);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000)
+
+/*
+ * Do priority-boost accounting for the start of a new grace period.
+ */
+static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
+{
+ rnp->boost_time = jiffies + RCU_BOOST_DELAY_JIFFIES;
+}
+
+/*
+ * Initialize the RCU-boost waitqueue.
+ */
+static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp)
+{
+ init_waitqueue_head(&rnp->boost_wq);
+}
+
+/*
+ * Create an RCU-boost kthread for the specified node if one does not
+ * already exist. We only create this kthread for preemptible RCU.
+ * 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)
+{
+ unsigned long flags;
+ struct sched_param sp;
+ struct task_struct *t;
+
+ if (&rcu_preempt_state != rsp)
+ return 0;
+ if (rnp->boost_kthread_task != NULL)
+ return 0;
+ t = kthread_create(rcu_boost_kthread, (void *)rnp,
+ "rcub%d", rnp_index);
+ if (IS_ERR(t))
+ return PTR_ERR(t);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ rnp->boost_kthread_task = t;
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ wake_up_process(t);
+ sp.sched_priority = RCU_KTHREAD_PRIO;
+ sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
+ return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void rcu_stop_boost_kthread(struct rcu_node *rnp)
+{
+ unsigned long flags;
+ struct task_struct *t;
+
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ t = rnp->boost_kthread_task;
+ rnp->boost_kthread_task = NULL;
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ if (t != NULL)
+ kthread_stop(t);
+}
+
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+
+#else /* #ifdef CONFIG_RCU_BOOST */
+
+static void rcu_initiate_boost(struct rcu_node *rnp)
+{
+}
+
+static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
+ cpumask_var_t cm)
+{
+}
+
+static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
+{
+}
+
+static void __init rcu_init_boost_waitqueue(struct rcu_node *rnp)
+{
+}
+
+static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
+ struct rcu_node *rnp,
+ int rnp_index)
+{
+ return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void rcu_stop_boost_kthread(struct rcu_node *rnp)
+{
+}
+
+#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+
+#endif /* #else #ifdef CONFIG_RCU_BOOST */
+
#ifndef CONFIG_SMP
void synchronize_sched_expedited(void)
*
* Because it is not legal to invoke rcu_process_callbacks() with irqs
* disabled, we do one pass of force_quiescent_state(), then do a
- * invoke_rcu_kthread() to cause rcu_process_callbacks() to be invoked later.
- * The per-cpu rcu_dyntick_drain variable controls the sequencing.
+ * invoke_rcu_cpu_kthread() to cause rcu_process_callbacks() to be invoked
+ * later. The per-cpu rcu_dyntick_drain variable controls the sequencing.
*/
int rcu_needs_cpu(int cpu)
{
/* If RCU callbacks are still pending, RCU still needs this CPU. */
if (c)
- invoke_rcu_kthread();
+ invoke_rcu_cpu_kthread();
return c;
}
projects / platform / upstream / kernel-adaptation-pc.git / commitdiff