static struct lock_class_key rcu_node_class[NUM_RCU_LVLS];
-#define RCU_STATE_INITIALIZER(name) { \
- .level = { &name.node[0] }, \
+#define RCU_STATE_INITIALIZER(structname) { \
+ .level = { &structname.node[0] }, \
.levelcnt = { \
NUM_RCU_LVL_0, /* root of hierarchy. */ \
NUM_RCU_LVL_1, \
.signaled = RCU_GP_IDLE, \
.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), \
+ .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \
+ .fqslock = __RAW_SPIN_LOCK_UNLOCKED(&structname.fqslock), \
.n_force_qs = 0, \
.n_force_qs_ngp = 0, \
+ .name = #structname, \
}
struct rcu_state rcu_sched_state = RCU_STATE_INITIALIZER(rcu_sched_state);
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;
-
+int rcu_scheduler_active __read_mostly;
+EXPORT_SYMBOL_GPL(rcu_scheduler_active);
/*
* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
*/
void rcu_sched_qs(int cpu)
{
- struct rcu_data *rdp;
+ struct rcu_data *rdp = &per_cpu(rcu_sched_data, cpu);
- rdp = &per_cpu(rcu_sched_data, cpu);
rdp->passed_quiesc_completed = rdp->gpnum - 1;
barrier();
rdp->passed_quiesc = 1;
- rcu_preempt_note_context_switch(cpu);
}
void rcu_bh_qs(int cpu)
{
- struct rcu_data *rdp;
+ struct rcu_data *rdp = &per_cpu(rcu_bh_data, cpu);
- rdp = &per_cpu(rcu_bh_data, cpu);
rdp->passed_quiesc_completed = rdp->gpnum - 1;
barrier();
rdp->passed_quiesc = 1;
}
+/*
+ * Note a context switch. This is a quiescent state for RCU-sched,
+ * and requires special handling for preemptible RCU.
+ */
+void rcu_note_context_switch(int cpu)
+{
+ rcu_sched_qs(cpu);
+ rcu_preempt_note_context_switch(cpu);
+}
+
#ifdef CONFIG_NO_HZ
DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
.dynticks_nesting = 1,
module_param(qhimark, int, 0);
module_param(qlowmark, int, 0);
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+int rcu_cpu_stall_suppress __read_mostly = RCU_CPU_STALL_SUPPRESS_INIT;
+module_param(rcu_cpu_stall_suppress, int, 0644);
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+
static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
static int rcu_pending(int cpu);
EXPORT_SYMBOL_GPL(rcu_batches_completed_bh);
/*
+ * Force a quiescent state for RCU BH.
+ */
+void rcu_bh_force_quiescent_state(void)
+{
+ force_quiescent_state(&rcu_bh_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_bh_force_quiescent_state);
+
+/*
+ * Force a quiescent state for RCU-sched.
+ */
+void rcu_sched_force_quiescent_state(void)
+{
+ force_quiescent_state(&rcu_sched_state, 0);
+}
+EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
+
+/*
* Does the CPU have callbacks ready to be invoked?
*/
static int
WARN_ON_ONCE(rdtp->dynticks & 0x1);
/* If the interrupt queued a callback, get out of dyntick mode. */
- if (__get_cpu_var(rcu_sched_data).nxtlist ||
- __get_cpu_var(rcu_bh_data).nxtlist)
+ if (__this_cpu_read(rcu_sched_data.nxtlist) ||
+ __this_cpu_read(rcu_bh_data.nxtlist))
set_need_resched();
}
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+int rcu_cpu_stall_suppress __read_mostly;
+
static void record_gp_stall_check_time(struct rcu_state *rsp)
{
rsp->gp_start = jiffies;
/* Only let one CPU complain about others per time interval. */
- spin_lock_irqsave(&rnp->lock, flags);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
delta = jiffies - rsp->jiffies_stall;
if (delta < RCU_STALL_RAT_DELAY || !rcu_gp_in_progress(rsp)) {
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
* due to CPU offlining.
*/
rcu_print_task_stall(rnp);
- spin_unlock_irqrestore(&rnp->lock, flags);
-
- /* OK, time to rat on our buddy... */
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
- printk(KERN_ERR "INFO: RCU detected CPU stalls:");
+ /*
+ * OK, time to rat on our buddy...
+ * See Documentation/RCU/stallwarn.txt for info on how to debug
+ * RCU CPU stall warnings.
+ */
+ printk(KERN_ERR "INFO: %s detected stalls on CPUs/tasks: {",
+ rsp->name);
rcu_for_each_leaf_node(rsp, rnp) {
+ raw_spin_lock_irqsave(&rnp->lock, flags);
rcu_print_task_stall(rnp);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
if (rnp->qsmask == 0)
continue;
for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
if (rnp->qsmask & (1UL << cpu))
printk(" %d", rnp->grplo + cpu);
}
- printk(" (detected by %d, t=%ld jiffies)\n",
+ printk("} (detected by %d, t=%ld jiffies)\n",
smp_processor_id(), (long)(jiffies - rsp->gp_start));
trigger_all_cpu_backtrace();
+ /* If so configured, complain about tasks blocking the grace period. */
+
+ rcu_print_detail_task_stall(rsp);
+
force_quiescent_state(rsp, 0); /* Kick them all. */
}
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);
- printk(KERN_ERR "INFO: RCU detected CPU %d stall (t=%lu jiffies)\n",
- smp_processor_id(), jiffies - rsp->gp_start);
+ /*
+ * OK, time to rat on ourselves...
+ * See Documentation/RCU/stallwarn.txt for info on how to debug
+ * RCU CPU stall warnings.
+ */
+ printk(KERN_ERR "INFO: %s detected stall on CPU %d (t=%lu jiffies)\n",
+ rsp->name, smp_processor_id(), jiffies - rsp->gp_start);
trigger_all_cpu_backtrace();
- spin_lock_irqsave(&rnp->lock, flags);
- if ((long)(jiffies - rsp->jiffies_stall) >= 0)
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ if (ULONG_CMP_GE(jiffies, rsp->jiffies_stall))
rsp->jiffies_stall =
jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
set_need_resched(); /* kick ourselves to get things going. */
}
long delta;
struct rcu_node *rnp;
- delta = jiffies - rsp->jiffies_stall;
+ if (rcu_cpu_stall_suppress)
+ return;
+ delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall);
rnp = rdp->mynode;
- if ((rnp->qsmask & rdp->grpmask) && delta >= 0) {
+ if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && delta >= 0) {
/* We haven't checked in, so go dump stack. */
print_cpu_stall(rsp);
}
}
+static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
+{
+ rcu_cpu_stall_suppress = 1;
+ return NOTIFY_DONE;
+}
+
+/**
+ * rcu_cpu_stall_reset - prevent further stall warnings in current grace period
+ *
+ * Set the stall-warning timeout way off into the future, thus preventing
+ * any RCU CPU stall-warning messages from appearing in the current set of
+ * RCU grace periods.
+ *
+ * The caller must disable hard irqs.
+ */
+void rcu_cpu_stall_reset(void)
+{
+ rcu_sched_state.jiffies_stall = jiffies + ULONG_MAX / 2;
+ rcu_bh_state.jiffies_stall = jiffies + ULONG_MAX / 2;
+ rcu_preempt_stall_reset();
+}
+
+static struct notifier_block rcu_panic_block = {
+ .notifier_call = rcu_panic,
+};
+
+static void __init check_cpu_stall_init(void)
+{
+ atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
+}
+
#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
static void record_gp_stall_check_time(struct rcu_state *rsp)
{
}
+void rcu_cpu_stall_reset(void)
+{
+}
+
+static void __init check_cpu_stall_init(void)
+{
+}
+
#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
/*
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;
+ /*
+ * If the current grace period is waiting for this CPU,
+ * set up to detect a quiescent state, otherwise don't
+ * go looking for one.
+ */
rdp->gpnum = rnp->gpnum;
+ if (rnp->qsmask & rdp->grpmask) {
+ rdp->qs_pending = 1;
+ rdp->passed_quiesc = 0;
+ } else
+ rdp->qs_pending = 0;
}
}
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. */
+ !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
local_irq_restore(flags);
return;
}
__note_new_gpnum(rsp, rnp, rdp);
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/*
/* Remember that we saw this grace-period completion. */
rdp->completed = rnp->completed;
+
+ /*
+ * If we were in an extended quiescent state, we may have
+ * missed some grace periods that others CPUs handled on
+ * our behalf. Catch up with this state to avoid noting
+ * spurious new grace periods. If another grace period
+ * has started, then rnp->gpnum will have advanced, so
+ * we will detect this later on.
+ */
+ if (ULONG_CMP_LT(rdp->gpnum, rdp->completed))
+ rdp->gpnum = rdp->completed;
+
+ /*
+ * If RCU does not need a quiescent state from this CPU,
+ * then make sure that this CPU doesn't go looking for one.
+ */
+ if ((rnp->qsmask & rdp->grpmask) == 0)
+ rdp->qs_pending = 0;
}
}
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. */
+ !raw_spin_trylock(&rnp->lock)) { /* irqs already off, so later. */
local_irq_restore(flags);
return;
}
__rcu_process_gp_end(rsp, rnp, rdp);
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/*
rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
__releases(rcu_get_root(rsp)->lock)
{
- struct rcu_data *rdp = rsp->rda[smp_processor_id()];
+ struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
struct rcu_node *rnp = rcu_get_root(rsp);
if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) {
+ if (cpu_needs_another_gp(rsp, rdp))
+ rsp->fqs_need_gp = 1;
if (rnp->completed == rsp->completed) {
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
/*
* Propagate new ->completed value to rcu_node structures
* of the next grace period to process their callbacks.
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
rnp->completed = rsp->completed;
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
local_irq_restore(flags);
return;
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);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
- spin_unlock(&rnp->lock); /* leave irqs disabled. */
+ raw_spin_unlock(&rnp->lock); /* leave irqs disabled. */
/* Exclude any concurrent CPU-hotplug operations. */
- spin_lock(&rsp->onofflock); /* irqs already disabled. */
+ raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */
/*
* Set the quiescent-state-needed bits in all the rcu_node
* irqs disabled.
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
rnp->gpnum = rsp->gpnum;
rnp->completed = rsp->completed;
if (rnp == rdp->mynode)
rcu_start_gp_per_cpu(rsp, rnp, rdp);
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
rnp = rcu_get_root(rsp);
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ raw_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);
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
}
/*
if (!(rnp->qsmask & mask)) {
/* Our bit has already been cleared, so done. */
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
rnp->qsmask &= ~mask;
if (rnp->qsmask != 0 || rcu_preempted_readers(rnp)) {
/* Other bits still set at this level, so done. */
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
mask = rnp->grpmask;
break;
}
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
rnp_c = rnp;
rnp = rnp->parent;
- spin_lock_irqsave(&rnp->lock, flags);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
WARN_ON_ONCE(rnp_c->qsmask);
}
struct rcu_node *rnp;
rnp = rdp->mynode;
- spin_lock_irqsave(&rnp->lock, flags);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
if (lastcomp != rnp->completed) {
/*
* race occurred.
*/
rdp->passed_quiesc = 0; /* try again later! */
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
mask = rdp->grpmask;
if ((rnp->qsmask & mask) == 0) {
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
} else {
rdp->qs_pending = 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.
+ * Move a dying CPU's RCU callbacks to online CPU's callback list.
+ * Synchronization is not required because this function executes
+ * in stop_machine() context.
*/
-static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp)
+static void rcu_send_cbs_to_online(struct rcu_state *rsp)
{
int i;
- struct rcu_data *rdp = rsp->rda[smp_processor_id()];
+ /* current DYING CPU is cleared in the cpu_online_mask */
+ int receive_cpu = cpumask_any(cpu_online_mask);
+ struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
+ struct rcu_data *receive_rdp = per_cpu_ptr(rsp->rda, receive_cpu);
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];
+
+ *receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxtlist;
+ receive_rdp->nxttail[RCU_NEXT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+ receive_rdp->qlen += rdp->qlen;
+ receive_rdp->n_cbs_adopted += rdp->qlen;
+ rdp->n_cbs_orphaned += rdp->qlen;
+
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);
}
/*
unsigned long flags;
unsigned long mask;
int need_report = 0;
- struct rcu_data *rdp = rsp->rda[cpu];
+ struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp;
/* Exclude any attempts to start a new grace period. */
- spin_lock_irqsave(&rsp->onofflock, flags);
+ raw_spin_lock_irqsave(&rsp->onofflock, flags);
/* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */
rnp = rdp->mynode; /* this is the outgoing CPU's rnp. */
mask = rdp->grpmask; /* rnp->grplo is constant. */
do {
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
rnp->qsmaskinit &= ~mask;
if (rnp->qsmaskinit != 0) {
if (rnp != rdp->mynode)
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
break;
}
if (rnp == rdp->mynode)
need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
else
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
mask = rnp->grpmask;
rnp = rnp->parent;
} while (rnp != NULL);
* because invoking rcu_report_unblock_qs_rnp() with ->onofflock
* held leads to deadlock.
*/
- spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
+ raw_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);
+ raw_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);
}
/*
#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_send_cbs_to_online(struct rcu_state *rsp)
{
}
while (list) {
next = list->next;
prefetch(next);
+ debug_rcu_head_unqueue(list);
list->func(list);
list = next;
if (++count >= rdp->blimit)
/* Update count, and requeue any remaining callbacks. */
rdp->qlen -= count;
+ rdp->n_cbs_invoked += count;
if (list != NULL) {
*tail = rdp->nxtlist;
rdp->nxtlist = list;
*/
void rcu_check_callbacks(int cpu, int user)
{
- if (!rcu_pending(cpu))
- return; /* if nothing for RCU to do. */
if (user ||
(idle_cpu(cpu) && rcu_scheduler_active &&
!in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
rcu_bh_qs(cpu);
}
rcu_preempt_check_callbacks(cpu);
- raise_softirq(RCU_SOFTIRQ);
+ if (rcu_pending(cpu))
+ raise_softirq(RCU_SOFTIRQ);
}
#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.
- * Returns 1 if the current grace period ends while scanning (possibly
- * because we made it end).
+ * The caller must have suppressed start of new grace periods.
*/
-static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
- int (*f)(struct rcu_data *))
+static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
{
unsigned long bit;
int cpu;
rcu_for_each_leaf_node(rsp, rnp) {
mask = 0;
- spin_lock_irqsave(&rnp->lock, flags);
- if (rnp->completed != lastcomp) {
- spin_unlock_irqrestore(&rnp->lock, flags);
- return 1;
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ if (!rcu_gp_in_progress(rsp)) {
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ return;
}
if (rnp->qsmask == 0) {
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
continue;
}
cpu = rnp->grplo;
bit = 1;
for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
- if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
+ if ((rnp->qsmask & bit) != 0 &&
+ f(per_cpu_ptr(rsp->rda, cpu)))
mask |= bit;
}
- if (mask != 0 && rnp->completed == lastcomp) {
+ if (mask != 0) {
/* rcu_report_qs_rnp() releases rnp->lock. */
rcu_report_qs_rnp(mask, rsp, rnp, flags);
continue;
}
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
- return 0;
}
/*
static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
{
unsigned long flags;
- long lastcomp;
struct rcu_node *rnp = rcu_get_root(rsp);
- u8 signaled;
- u8 forcenow;
- u8 gpdone;
if (!rcu_gp_in_progress(rsp))
return; /* No grace period in progress, nothing to force. */
- if (!spin_trylock_irqsave(&rsp->fqslock, flags)) {
+ if (!raw_spin_trylock_irqsave(&rsp->fqslock, flags)) {
rsp->n_force_qs_lh++; /* Inexact, can lose counts. Tough! */
return; /* Someone else is already on the job. */
}
- if (relaxed &&
- (long)(rsp->jiffies_force_qs - jiffies) >= 0)
+ if (relaxed && ULONG_CMP_GE(rsp->jiffies_force_qs, jiffies))
goto unlock_fqs_ret; /* no emergency and done recently. */
rsp->n_force_qs++;
- spin_lock(&rnp->lock); /* irqs already disabled */
- lastcomp = rsp->gpnum - 1;
- signaled = rsp->signaled;
+ raw_spin_lock(&rnp->lock); /* irqs already disabled */
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
if(!rcu_gp_in_progress(rsp)) {
rsp->n_force_qs_ngp++;
- spin_unlock(&rnp->lock); /* irqs remain disabled */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
goto unlock_fqs_ret; /* no GP in progress, time updated. */
}
rsp->fqs_active = 1;
- switch (signaled) {
+ switch (rsp->signaled) {
case RCU_GP_IDLE:
case RCU_GP_INIT:
break; /* grace period idle or initializing, ignore. */
case RCU_SAVE_DYNTICK:
-
- spin_unlock(&rnp->lock); /* irqs remain disabled */
if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK)
break; /* So gcc recognizes the dead code. */
- /* Record dyntick-idle state. */
- gpdone = rcu_process_dyntick(rsp, lastcomp,
- dyntick_save_progress_counter);
- spin_lock(&rnp->lock); /* irqs already disabled */
- if (gpdone)
- break;
- /* fall into next case. */
-
- case RCU_SAVE_COMPLETED:
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
- /* Update state, record completion counter. */
- forcenow = 0;
- if (lastcomp + 1 == rsp->gpnum &&
- lastcomp == rsp->completed &&
- rsp->signaled == signaled) {
+ /* Record dyntick-idle state. */
+ force_qs_rnp(rsp, dyntick_save_progress_counter);
+ raw_spin_lock(&rnp->lock); /* irqs already disabled */
+ if (rcu_gp_in_progress(rsp))
rsp->signaled = RCU_FORCE_QS;
- rsp->completed_fqs = lastcomp;
- forcenow = signaled == RCU_SAVE_COMPLETED;
- }
- if (!forcenow)
- break;
- /* fall into next case. */
+ break;
case RCU_FORCE_QS:
/* Check dyntick-idle state, send IPI to laggarts. */
- spin_unlock(&rnp->lock); /* irqs remain disabled */
- gpdone = rcu_process_dyntick(rsp, rsp->completed_fqs,
- rcu_implicit_dynticks_qs);
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
+ force_qs_rnp(rsp, rcu_implicit_dynticks_qs);
/* Leave state in case more forcing is required. */
- spin_lock(&rnp->lock); /* irqs already disabled */
+ raw_spin_lock(&rnp->lock); /* irqs already disabled */
break;
}
rsp->fqs_active = 0;
- spin_unlock(&rnp->lock); /* irqs remain disabled */
+ if (rsp->fqs_need_gp) {
+ raw_spin_unlock(&rsp->fqslock); /* irqs remain disabled */
+ rsp->fqs_need_gp = 0;
+ rcu_start_gp(rsp, flags); /* releases rnp->lock */
+ return;
+ }
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
unlock_fqs_ret:
- spin_unlock_irqrestore(&rsp->fqslock, flags);
+ raw_spin_unlock_irqrestore(&rsp->fqslock, flags);
}
#else /* #ifdef CONFIG_SMP */
* If an RCU GP has gone long enough, go check for dyntick
* idle CPUs and, if needed, send resched IPIs.
*/
- if ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)
+ if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies))
force_quiescent_state(rsp, 1);
/*
/* Does this CPU require a not-yet-started grace period? */
if (cpu_needs_another_gp(rsp, rdp)) {
- spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags);
+ raw_spin_lock_irqsave(&rcu_get_root(rsp)->lock, flags);
rcu_start_gp(rsp, flags); /* releases above lock */
}
* grace-period manipulations above.
*/
smp_mb(); /* See above block comment. */
+
+ /* If we are last CPU on way to dyntick-idle mode, accelerate it. */
+ rcu_needs_cpu_flush();
}
static void
unsigned long flags;
struct rcu_data *rdp;
+ debug_rcu_head_queue(head);
head->func = func;
head->next = NULL;
* a quiescent state betweentimes.
*/
local_irq_save(flags);
- rdp = rsp->rda[smp_processor_id()];
- rcu_process_gp_end(rsp, rdp);
- check_for_new_grace_period(rsp, rdp);
+ rdp = this_cpu_ptr(rsp->rda);
/* Add the callback to our list. */
*rdp->nxttail[RCU_NEXT_TAIL] = head;
rdp->nxttail[RCU_NEXT_TAIL] = &head->next;
- /* Start a new grace period if one not already started. */
- if (!rcu_gp_in_progress(rsp)) {
- unsigned long nestflag;
- struct rcu_node *rnp_root = rcu_get_root(rsp);
-
- spin_lock_irqsave(&rnp_root->lock, nestflag);
- rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */
- }
-
/*
* Force the grace period if too many callbacks or too long waiting.
* Enforce hysteresis, and don't invoke force_quiescent_state()
* 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;
- 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)
+
+ /* Are we ignoring a completed grace period? */
+ rcu_process_gp_end(rsp, rdp);
+ check_for_new_grace_period(rsp, rdp);
+
+ /* Start a new grace period if one not already started. */
+ if (!rcu_gp_in_progress(rsp)) {
+ unsigned long nestflag;
+ struct rcu_node *rnp_root = rcu_get_root(rsp);
+
+ raw_spin_lock_irqsave(&rnp_root->lock, nestflag);
+ rcu_start_gp(rsp, nestflag); /* rlses rnp_root->lock */
+ } else {
+ /* Give the grace period a kick. */
+ rdp->blimit = LONG_MAX;
+ 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 (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies))
force_quiescent_state(rsp, 1);
local_irq_restore(flags);
}
if (rcu_blocking_is_gp())
return;
+ init_rcu_head_on_stack(&rcu.head);
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);
+ destroy_rcu_head_on_stack(&rcu.head);
}
EXPORT_SYMBOL_GPL(synchronize_sched);
if (rcu_blocking_is_gp())
return;
+ init_rcu_head_on_stack(&rcu.head);
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);
+ destroy_rcu_head_on_stack(&rcu.head);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_bh);
check_cpu_stall(rsp, rdp);
/* Is the RCU core waiting for a quiescent state from this CPU? */
- if (rdp->qs_pending) {
+ if (rdp->qs_pending && !rdp->passed_quiesc) {
+
+ /*
+ * If force_quiescent_state() coming soon and this CPU
+ * needs a quiescent state, and this is either RCU-sched
+ * or RCU-bh, force a local reschedule.
+ */
rdp->n_rp_qs_pending++;
+ if (!rdp->preemptable &&
+ ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1,
+ jiffies))
+ set_need_resched();
+ } else if (rdp->qs_pending && rdp->passed_quiesc) {
+ rdp->n_rp_report_qs++;
return 1;
}
/* Has an RCU GP gone long enough to send resched IPIs &c? */
if (rcu_gp_in_progress(rsp) &&
- ((long)(ACCESS_ONCE(rsp->jiffies_force_qs) - jiffies) < 0)) {
+ ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies)) {
rdp->n_rp_need_fqs++;
return 1;
}
/*
* Check to see if any future RCU-related work will need to be done
* by the current CPU, even if none need be done immediately, returning
- * 1 if so. This function is part of the RCU implementation; it is -not-
- * an exported member of the RCU API.
+ * 1 if so.
*/
-int rcu_needs_cpu(int cpu)
+static int rcu_needs_cpu_quick_check(int cpu)
{
/* RCU callbacks either ready or pending? */
return per_cpu(rcu_sched_data, cpu).nxtlist ||
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);
* decrement rcu_barrier_cpu_count -- otherwise the first CPU
* might complete its grace period before all of the other CPUs
* did their increment, causing this function to return too
- * early.
+ * early. Note that on_each_cpu() disables irqs, which prevents
+ * any CPUs from coming online or going offline until each online
+ * CPU has queued its RCU-barrier callback.
*/
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);
{
unsigned long flags;
int i;
- struct rcu_data *rdp = rsp->rda[cpu];
+ struct rcu_data *rdp = per_cpu_ptr(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);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
rdp->nxtlist = NULL;
for (i = 0; i < RCU_NEXT_SIZE; i++)
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
#endif /* #ifdef CONFIG_NO_HZ */
rdp->cpu = cpu;
- spin_unlock_irqrestore(&rnp->lock, flags);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/*
{
unsigned long flags;
unsigned long mask;
- struct rcu_data *rdp = rsp->rda[cpu];
+ struct rcu_data *rdp = per_cpu_ptr(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);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
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->qlen_last_fqs_check = 0;
rdp->n_force_qs_snap = rsp->n_force_qs;
rdp->blimit = blimit;
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
/*
* A new grace period might start here. If so, we won't be part
*/
/* Exclude any attempts to start a new GP on large systems. */
- spin_lock(&rsp->onofflock); /* irqs already disabled. */
+ raw_spin_lock(&rsp->onofflock); /* irqs already disabled. */
/* Add CPU to rcu_node bitmasks. */
rnp = rdp->mynode;
mask = rdp->grpmask;
do {
/* Exclude any attempts to start a new GP on small systems. */
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
rnp->qsmaskinit |= mask;
mask = rnp->grpmask;
if (rnp == rdp->mynode) {
rdp->completed = rnp->completed;
rdp->passed_quiesc_completed = rnp->completed - 1;
}
- spin_unlock(&rnp->lock); /* irqs already disabled. */
+ raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
rnp = rnp->parent;
} while (rnp != NULL && !(rnp->qsmaskinit & mask));
- spin_unlock_irqrestore(&rsp->onofflock, flags);
+ raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
}
static void __cpuinit rcu_online_cpu(int cpu)
case CPU_DYING:
case CPU_DYING_FROZEN:
/*
- * 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().
- * 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.
+ * The whole machine is "stopped" except this CPU, so we can
+ * touch any data without introducing corruption. We send the
+ * dying CPU's callbacks to an arbitrarily chosen online CPU.
*/
- rcu_send_cbs_to_orphanage(&rcu_bh_state);
- rcu_send_cbs_to_orphanage(&rcu_sched_state);
- rcu_preempt_send_cbs_to_orphanage();
+ rcu_send_cbs_to_online(&rcu_bh_state);
+ rcu_send_cbs_to_online(&rcu_sched_state);
+ rcu_preempt_send_cbs_to_online();
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
}
/*
+ * 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. This function also enables RCU lockdep checking.
+ */
+void rcu_scheduler_starting(void)
+{
+ WARN_ON(num_online_cpus() != 1);
+ WARN_ON(nr_context_switches() > 0);
+ rcu_scheduler_active = 1;
+}
+
+/*
* Compute the per-level fanout, either using the exact fanout specified
* or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT.
*/
{
int i;
- for (i = NUM_RCU_LVLS - 1; i >= 0; i--)
+ for (i = NUM_RCU_LVLS - 1; i > 0; i--)
rsp->levelspread[i] = CONFIG_RCU_FANOUT;
+ rsp->levelspread[0] = RCU_FANOUT_LEAF;
}
#else /* #ifdef CONFIG_RCU_FANOUT_EXACT */
static void __init rcu_init_levelspread(struct rcu_state *rsp)
/*
* Helper function for rcu_init() that initializes one rcu_state structure.
*/
-static void __init rcu_init_one(struct rcu_state *rsp)
+static void __init rcu_init_one(struct rcu_state *rsp,
+ struct rcu_data __percpu *rda)
{
+ static char *buf[] = { "rcu_node_level_0",
+ "rcu_node_level_1",
+ "rcu_node_level_2",
+ "rcu_node_level_3" }; /* Match MAX_RCU_LVLS */
int cpustride = 1;
int i;
int j;
struct rcu_node *rnp;
+ BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf)); /* Fix buf[] init! */
+
/* Initialize the level-tracking arrays. */
for (i = 1; i < NUM_RCU_LVLS; i++)
cpustride *= rsp->levelspread[i];
rnp = rsp->level[i];
for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
- spin_lock_init(&rnp->lock);
- lockdep_set_class(&rnp->lock, &rcu_node_class[i]);
+ raw_spin_lock_init(&rnp->lock);
+ lockdep_set_class_and_name(&rnp->lock,
+ &rcu_node_class[i], buf[i]);
rnp->gpnum = 0;
rnp->qsmask = 0;
rnp->qsmaskinit = 0;
INIT_LIST_HEAD(&rnp->blocked_tasks[3]);
}
}
-}
-/*
- * Helper macro for __rcu_init() and __rcu_init_preempt(). To be used
- * nowhere else! Assigns leaf node pointers into each CPU's rcu_data
- * structure.
- */
-#define RCU_INIT_FLAVOR(rsp, rcu_data) \
-do { \
- int i; \
- int j; \
- struct rcu_node *rnp; \
- \
- rcu_init_one(rsp); \
- rnp = (rsp)->level[NUM_RCU_LVLS - 1]; \
- j = 0; \
- for_each_possible_cpu(i) { \
- if (i > rnp[j].grphi) \
- j++; \
- per_cpu(rcu_data, i).mynode = &rnp[j]; \
- (rsp)->rda[i] = &per_cpu(rcu_data, i); \
- rcu_boot_init_percpu_data(i, rsp); \
- } \
-} while (0)
+ rsp->rda = rda;
+ rnp = rsp->level[NUM_RCU_LVLS - 1];
+ for_each_possible_cpu(i) {
+ while (i > rnp->grphi)
+ rnp++;
+ per_cpu_ptr(rsp->rda, i)->mynode = rnp;
+ rcu_boot_init_percpu_data(i, rsp);
+ }
+}
void __init rcu_init(void)
{
- int i;
+ int cpu;
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_one(&rcu_sched_state, &rcu_sched_data);
+ rcu_init_one(&rcu_bh_state, &rcu_bh_data);
__rcu_init_preempt();
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
* 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);
+ for_each_online_cpu(cpu)
+ rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
+ check_cpu_stall_init();
}
#include "rcutree_plugin.h"
projects / linux-flexiantxendom0-natty.git / blobdiff