.gpnum = -300, \
.completed = -300, \
.onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \
+ .orphan_cbs_list = NULL, \
+ .orphan_cbs_tail = &name.orphan_cbs_list, \
+ .orphan_qlen = 0, \
.fqslock = __SPIN_LOCK_UNLOCKED(&name.fqslock), \
.n_force_qs = 0, \
.n_force_qs_ngp = 0, \
#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * Move a dying CPU's RCU callbacks to the ->orphan_cbs_list for the
+ * specified flavor of RCU. The callbacks will be adopted by the next
+ * _rcu_barrier() invocation or by the CPU_DEAD notifier, whichever
+ * comes first. Because this is invoked from the CPU_DYING notifier,
+ * irqs are already disabled.
+ */
+static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp)
+{
+ int i;
+ struct rcu_data *rdp = rsp->rda[smp_processor_id()];
+
+ if (rdp->nxtlist == NULL)
+ return; /* irqs disabled, so comparison is stable. */
+ spin_lock(&rsp->onofflock); /* irqs already disabled. */
+ *rsp->orphan_cbs_tail = rdp->nxtlist;
+ rsp->orphan_cbs_tail = rdp->nxttail[RCU_NEXT_TAIL];
+ rdp->nxtlist = NULL;
+ for (i = 0; i < RCU_NEXT_SIZE; i++)
+ rdp->nxttail[i] = &rdp->nxtlist;
+ rsp->orphan_qlen += rdp->qlen;
+ rdp->qlen = 0;
+ spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
+}
+
+/*
+ * Adopt previously orphaned RCU callbacks.
+ */
+static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
+{
+ unsigned long flags;
+ struct rcu_data *rdp;
+
+ spin_lock_irqsave(&rsp->onofflock, flags);
+ rdp = rsp->rda[smp_processor_id()];
+ if (rsp->orphan_cbs_list == NULL) {
+ spin_unlock_irqrestore(&rsp->onofflock, flags);
+ return;
+ }
+ *rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list;
+ rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_tail;
+ rdp->qlen += rsp->orphan_qlen;
+ rsp->orphan_cbs_list = NULL;
+ rsp->orphan_cbs_tail = &rsp->orphan_cbs_list;
+ rsp->orphan_qlen = 0;
+ spin_unlock_irqrestore(&rsp->onofflock, flags);
+}
+
/*
* Remove the outgoing CPU from the bitmasks in the rcu_node hierarchy
* and move all callbacks from the outgoing CPU to the current one.
*/
static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
{
- int i;
unsigned long flags;
long lastcomp;
unsigned long mask;
struct rcu_data *rdp = rsp->rda[cpu];
- struct rcu_data *rdp_me;
struct rcu_node *rnp;
/* Exclude any attempts to start a new grace period. */
} while (rnp != NULL);
lastcomp = rsp->completed;
- spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
+ spin_unlock_irqrestore(&rsp->onofflock, flags);
- /*
- * Move callbacks from the outgoing CPU to the running CPU.
- * Note that the outgoing CPU is now quiescent, so it is now
- * (uncharacteristically) safe to access its rcu_data structure.
- * Note also that we must carefully retain the order of the
- * outgoing CPU's callbacks in order for rcu_barrier() to work
- * correctly. Finally, note that we start all the callbacks
- * afresh, even those that have passed through a grace period
- * and are therefore ready to invoke. The theory is that hotplug
- * events are rare, and that if they are frequent enough to
- * indefinitely delay callbacks, you have far worse things to
- * be worrying about.
- */
- if (rdp->nxtlist != NULL) {
- rdp_me = rsp->rda[smp_processor_id()];
- *rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist;
- rdp_me->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
- rdp->nxtlist = NULL;
- for (i = 0; i < RCU_NEXT_SIZE; i++)
- rdp->nxttail[i] = &rdp->nxtlist;
- rdp_me->qlen += rdp->qlen;
- rdp->qlen = 0;
- }
- local_irq_restore(flags);
+ rcu_adopt_orphan_cbs(rsp);
}
/*
#else /* #ifdef CONFIG_HOTPLUG_CPU */
+static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp)
+{
+}
+
+static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
+{
+}
+
static void rcu_offline_cpu(int cpu)
{
}
static atomic_t rcu_barrier_cpu_count;
static DEFINE_MUTEX(rcu_barrier_mutex);
static struct completion rcu_barrier_completion;
-static atomic_t rcu_migrate_type_count = ATOMIC_INIT(0);
-static struct rcu_head rcu_migrate_head[3];
-static DECLARE_WAIT_QUEUE_HEAD(rcu_migrate_wq);
static void rcu_barrier_callback(struct rcu_head *notused)
{
call_rcu_func(head, rcu_barrier_callback);
}
-static inline void wait_migrated_callbacks(void)
-{
- wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count));
- smp_mb(); /* In case we didn't sleep. */
-}
-
/*
* Orchestrate the specified type of RCU barrier, waiting for all
* RCU callbacks of the specified type to complete.
*/
-static void _rcu_barrier(void (*call_rcu_func)(struct rcu_head *head,
+static void _rcu_barrier(struct rcu_state *rsp,
+ void (*call_rcu_func)(struct rcu_head *head,
void (*func)(struct rcu_head *head)))
{
BUG_ON(in_interrupt());
- /* Take cpucontrol mutex to protect against CPU hotplug */
+ /* Take mutex to serialize concurrent rcu_barrier() requests. */
mutex_lock(&rcu_barrier_mutex);
init_completion(&rcu_barrier_completion);
/*
* early.
*/
atomic_set(&rcu_barrier_cpu_count, 1);
+ preempt_disable(); /* stop CPU_DYING from filling orphan_cbs_list */
+ rcu_adopt_orphan_cbs(rsp);
on_each_cpu(rcu_barrier_func, (void *)call_rcu_func, 1);
+ preempt_enable(); /* CPU_DYING can again fill orphan_cbs_list */
if (atomic_dec_and_test(&rcu_barrier_cpu_count))
complete(&rcu_barrier_completion);
wait_for_completion(&rcu_barrier_completion);
mutex_unlock(&rcu_barrier_mutex);
- wait_migrated_callbacks();
-}
-
-/**
- * rcu_barrier - Wait until all in-flight call_rcu() callbacks complete.
- */
-void rcu_barrier(void)
-{
- _rcu_barrier(call_rcu);
}
-EXPORT_SYMBOL_GPL(rcu_barrier);
/**
* rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete.
*/
void rcu_barrier_bh(void)
{
- _rcu_barrier(call_rcu_bh);
+ _rcu_barrier(&rcu_bh_state, call_rcu_bh);
}
EXPORT_SYMBOL_GPL(rcu_barrier_bh);
*/
void rcu_barrier_sched(void)
{
- _rcu_barrier(call_rcu_sched);
+ _rcu_barrier(&rcu_sched_state, call_rcu_sched);
}
EXPORT_SYMBOL_GPL(rcu_barrier_sched);
-static void rcu_migrate_callback(struct rcu_head *notused)
-{
- if (atomic_dec_and_test(&rcu_migrate_type_count))
- wake_up(&rcu_migrate_wq);
-}
-
/*
* Do boot-time initialization of a CPU's per-CPU RCU data.
*/
case CPU_UP_PREPARE_FROZEN:
rcu_online_cpu(cpu);
break;
- case CPU_DOWN_PREPARE:
- case CPU_DOWN_PREPARE_FROZEN:
- /* Don't need to wait until next removal operation. */
- /* rcu_migrate_head is protected by cpu_add_remove_lock */
- wait_migrated_callbacks();
- break;
case CPU_DYING:
case CPU_DYING_FROZEN:
/*
- * preempt_disable() in on_each_cpu() prevents stop_machine(),
+ * preempt_disable() in _rcu_barrier() prevents stop_machine(),
* so when "on_each_cpu(rcu_barrier_func, (void *)type, 1);"
- * returns, all online cpus have queued rcu_barrier_func(),
- * and the dead cpu(if it exist) queues rcu_migrate_callback()s.
- *
- * These callbacks ensure _rcu_barrier() waits for all
- * RCU callbacks of the specified type to complete.
+ * returns, all online cpus have queued rcu_barrier_func().
+ * The dying CPU clears its cpu_online_mask bit and
+ * moves all of its RCU callbacks to ->orphan_cbs_list
+ * in the context of stop_machine(), so subsequent calls
+ * to _rcu_barrier() will adopt these callbacks and only
+ * then queue rcu_barrier_func() on all remaining CPUs.
*/
- atomic_set(&rcu_migrate_type_count, 3);
- call_rcu_bh(rcu_migrate_head, rcu_migrate_callback);
- call_rcu_sched(rcu_migrate_head + 1, rcu_migrate_callback);
- call_rcu(rcu_migrate_head + 2, rcu_migrate_callback);
+ rcu_send_cbs_to_orphanage(&rcu_bh_state);
+ rcu_send_cbs_to_orphanage(&rcu_sched_state);
+ rcu_preempt_send_cbs_to_orphanage();
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
projects / deliverable / linux.git / blobdiff