#include <linux/cpu.h>
#include <linux/mutex.h>
#include <linux/time.h>
+#include <linux/kernel_stat.h>
#include "rcutree.h"
/* Data structures. */
-static struct lock_class_key rcu_root_class;
+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, \
NUM_RCU_LVL_2, \
- NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \
+ NUM_RCU_LVL_3, \
+ NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \
}, \
.signaled = RCU_GP_IDLE, \
.gpnum = -300, \
.completed = -300, \
- .onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \
+ .onofflock = __RAW_SPIN_LOCK_UNLOCKED(&structname.onofflock), \
.orphan_cbs_list = NULL, \
- .orphan_cbs_tail = &name.orphan_cbs_list, \
+ .orphan_cbs_tail = &structname.orphan_cbs_list, \
.orphan_qlen = 0, \
- .fqslock = __SPIN_LOCK_UNLOCKED(&name.fqslock), \
+ .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);
+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,
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
return &rsp->node[0];
}
-/*
- * Record the specified "completed" value, which is later used to validate
- * dynticks counter manipulations and CPU-offline checks. Specify
- * "rsp->completed - 1" to unconditionally invalidate any future dynticks
- * manipulations and CPU-offline checks. Such invalidation is useful at
- * the beginning of a grace period.
- */
-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
-{
- rsp->completed_fqs = comp;
-}
-
#ifdef CONFIG_SMP
/*
- * Recall the previously recorded value of the completion for dynticks.
- */
-static long dyntick_recall_completed(struct rcu_state *rsp)
-{
- return rsp->completed_fqs;
-}
-
-/*
* If the specified CPU is offline, tell the caller that it is in
* a quiescent state. Otherwise, whack it with a reschedule IPI.
* Grace periods can end up waiting on an offline CPU when that
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+int rcu_cpu_stall_panicking __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);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
/* OK, time to rat on our buddy... */
- printk(KERN_ERR "INFO: RCU detected CPU stalls:");
+ 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);
+ 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;
+ if (rcu_cpu_stall_panicking)
+ return;
delta = jiffies - rsp->jiffies_stall;
rnp = rdp->mynode;
if ((rnp->qsmask & rdp->grpmask) && delta >= 0) {
}
}
+static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
+{
+ rcu_cpu_stall_panicking = 1;
+ return NOTIFY_DONE;
+}
+
+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)
{
}
+static void __init check_cpu_stall_init(void)
+{
+}
+
#endif /* #else #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
/*
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);
}
/*
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);
}
/*
struct rcu_data *rdp = rsp->rda[smp_processor_id()];
struct rcu_node *rnp = rcu_get_root(rsp);
- if (!cpu_needs_another_gp(rsp, rdp)) {
+ 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;
rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
record_gp_stall_check_time(rsp);
- dyntick_record_completed(rsp, rsp->completed - 1);
/* Special-case the common single-level case. */
if (NUM_RCU_NODES == 1) {
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);
}
/*
- * Clean up after the prior grace period and let rcu_start_gp() start up
- * the next grace period if one is needed. Note that the caller must
- * hold rnp->lock, as required by rcu_start_gp(), which will release it.
+ * Report a full set of quiescent states to the specified rcu_state
+ * data structure. This involves cleaning up after the prior grace
+ * period and letting rcu_start_gp() start up the next grace period
+ * if one is needed. Note that the caller must hold rnp->lock, as
+ * required by rcu_start_gp(), which will release it.
*/
-static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags)
+static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
__releases(rcu_get_root(rsp)->lock)
{
WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
}
/*
- * Similar to cpu_quiet(), for which it is a helper function. Allows
- * a group of CPUs to be quieted at one go, though all the CPUs in the
- * group must be represented by the same leaf rcu_node structure.
- * That structure's lock must be held upon entry, and it is released
- * before return.
+ * Similar to rcu_report_qs_rdp(), for which it is a helper function.
+ * Allows quiescent states for a group of CPUs to be reported at one go
+ * to the specified rcu_node structure, though all the CPUs in the group
+ * must be represented by the same rcu_node structure (which need not be
+ * a leaf rcu_node structure, though it often will be). That structure's
+ * lock must be held upon entry, and it is released before return.
*/
static void
-cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
- unsigned long flags)
+rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
+ struct rcu_node *rnp, unsigned long flags)
__releases(rnp->lock)
{
struct rcu_node *rnp_c;
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);
}
/*
* Get here if we are the last CPU to pass through a quiescent
- * state for this grace period. Invoke cpu_quiet_msk_finish()
+ * state for this grace period. Invoke rcu_report_qs_rsp()
* to clean up and start the next grace period if one is needed.
*/
- cpu_quiet_msk_finish(rsp, flags); /* releases rnp->lock. */
+ rcu_report_qs_rsp(rsp, flags); /* releases rnp->lock. */
}
/*
- * Record a quiescent state for the specified CPU, which must either be
- * the current CPU. The lastcomp argument is used to make sure we are
- * still in the grace period of interest. We don't want to end the current
- * grace period based on quiescent states detected in an earlier grace
- * period!
+ * Record a quiescent state for the specified CPU to that CPU's rcu_data
+ * structure. This must be either called from the specified CPU, or
+ * called when the specified CPU is known to be offline (and when it is
+ * also known that no other CPU is concurrently trying to help the offline
+ * CPU). The lastcomp argument is used to make sure we are still in the
+ * grace period of interest. We don't want to end the current grace period
+ * based on quiescent states detected in an earlier grace period!
*/
static void
-cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
+rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
{
unsigned long flags;
unsigned long mask;
struct rcu_node *rnp;
rnp = rdp->mynode;
- spin_lock_irqsave(&rnp->lock, flags);
- if (lastcomp != ACCESS_ONCE(rsp->completed)) {
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ if (lastcomp != rnp->completed) {
/*
* Someone beat us to it for this grace period, so leave.
* The race with GP start is resolved by the fact that we
* hold the leaf rcu_node lock, so that the per-CPU bits
* cannot yet be initialized -- so we would simply find our
- * CPU's bit already cleared in cpu_quiet_msk() if this race
- * occurred.
+ * CPU's bit already cleared in rcu_report_qs_rnp() if this
+ * 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;
*/
rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
- cpu_quiet_msk(mask, rsp, rnp, flags); /* releases rnp->lock */
+ rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */
}
}
if (!rdp->passed_quiesc)
return;
- /* Tell RCU we are done (but cpu_quiet() will be the judge of that). */
- cpu_quiet(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
+ /*
+ * Tell RCU we are done (but rcu_report_qs_rdp() will be the
+ * judge of that).
+ */
+ rcu_report_qs_rdp(rdp->cpu, rsp, rdp, rdp->passed_quiesc_completed);
}
#ifdef CONFIG_HOTPLUG_CPU
if (rdp->nxtlist == NULL)
return; /* irqs disabled, so comparison is stable. */
- spin_lock(&rsp->onofflock); /* irqs already disabled. */
+ raw_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;
rdp->nxttail[i] = &rdp->nxtlist;
rsp->orphan_qlen += rdp->qlen;
rdp->qlen = 0;
- spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
+ raw_spin_unlock(&rsp->onofflock); /* irqs remain disabled. */
}
/*
unsigned long flags;
struct rcu_data *rdp;
- spin_lock_irqsave(&rsp->onofflock, flags);
+ raw_spin_lock_irqsave(&rsp->onofflock, flags);
rdp = rsp->rda[smp_processor_id()];
if (rsp->orphan_cbs_list == NULL) {
- spin_unlock_irqrestore(&rsp->onofflock, flags);
+ raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
return;
}
*rdp->nxttail[RCU_NEXT_TAIL] = rsp->orphan_cbs_list;
rsp->orphan_cbs_list = NULL;
rsp->orphan_cbs_tail = &rsp->orphan_cbs_list;
rsp->orphan_qlen = 0;
- spin_unlock_irqrestore(&rsp->onofflock, flags);
+ raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
}
/*
static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
{
unsigned long flags;
- long lastcomp;
unsigned long mask;
+ int need_report = 0;
struct rcu_data *rdp = 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) {
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ if (rnp != rdp->mynode)
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
break;
}
-
- /*
- * If there was a task blocking the current grace period,
- * and if all CPUs have checked in, we need to propagate
- * the quiescent state up the rcu_node hierarchy. But that
- * is inconvenient at the moment due to deadlock issues if
- * this should end the current grace period. So set the
- * offlined CPU's bit in ->qsmask in order to force the
- * next force_quiescent_state() invocation to clean up this
- * mess in a deadlock-free manner.
- */
- if (rcu_preempt_offline_tasks(rsp, rnp, rdp) && !rnp->qsmask)
- rnp->qsmask |= mask;
-
+ if (rnp == rdp->mynode)
+ need_report = rcu_preempt_offline_tasks(rsp, rnp, rdp);
+ else
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
mask = rnp->grpmask;
- spin_unlock(&rnp->lock); /* irqs remain disabled. */
rnp = rnp->parent;
} while (rnp != NULL);
- lastcomp = rsp->completed;
- spin_unlock_irqrestore(&rsp->onofflock, flags);
+ /*
+ * We still hold the leaf rcu_node structure lock here, and
+ * irqs are still disabled. The reason for this subterfuge is
+ * because invoking rcu_report_unblock_qs_rnp() with ->onofflock
+ * held leads to deadlock.
+ */
+ 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
+ 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);
}
*/
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 (rsp->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;
if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
mask |= bit;
}
- if (mask != 0 && rsp->completed == lastcomp) {
+ if (mask != 0) {
- /* cpu_quiet_msk() releases rnp->lock. */
- cpu_quiet_msk(mask, rsp, rnp, flags);
+ /* 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;
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)
- goto unlock_ret; /* no emergency and done recently. */
+ 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);
- lastcomp = rsp->completed;
- signaled = rsp->signaled;
+ raw_spin_lock(&rnp->lock); /* irqs already disabled */
rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;
- if (lastcomp == rsp->gpnum) {
+ if(!rcu_gp_in_progress(rsp)) {
rsp->n_force_qs_ngp++;
- spin_unlock(&rnp->lock);
- goto unlock_ret; /* no GP in progress, time updated. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
+ goto unlock_fqs_ret; /* no GP in progress, time updated. */
}
- spin_unlock(&rnp->lock);
- switch (signaled) {
+ rsp->fqs_active = 1;
+ switch (rsp->signaled) {
case RCU_GP_IDLE:
case RCU_GP_INIT:
break; /* grace period idle or initializing, ignore. */
case RCU_SAVE_DYNTICK:
-
if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK)
break; /* So gcc recognizes the dead code. */
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
+
/* Record dyntick-idle state. */
- if (rcu_process_dyntick(rsp, lastcomp,
- dyntick_save_progress_counter))
- goto unlock_ret;
- /* fall into next case. */
-
- case RCU_SAVE_COMPLETED:
-
- /* Update state, record completion counter. */
- forcenow = 0;
- spin_lock(&rnp->lock);
- if (lastcomp == rsp->completed &&
- rsp->signaled == signaled) {
+ 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;
- dyntick_record_completed(rsp, lastcomp);
- forcenow = signaled == RCU_SAVE_COMPLETED;
- }
- spin_unlock(&rnp->lock);
- if (!forcenow)
- break;
- /* fall into next case. */
+ break;
case RCU_FORCE_QS:
/* Check dyntick-idle state, send IPI to laggarts. */
- if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),
- rcu_implicit_dynticks_qs))
- goto unlock_ret;
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
+ force_qs_rnp(rsp, rcu_implicit_dynticks_qs);
/* Leave state in case more forcing is required. */
+ raw_spin_lock(&rnp->lock); /* irqs already disabled */
break;
}
-unlock_ret:
- spin_unlock_irqrestore(&rsp->fqslock, flags);
+ rsp->fqs_active = 0;
+ 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:
+ 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 nestflag;
struct rcu_node *rnp_root = rcu_get_root(rsp);
- spin_lock_irqsave(&rnp_root->lock, nestflag);
+ raw_spin_lock_irqsave(&rnp_root->lock, nestflag);
rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */
}
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)
+ } else if (ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs), jiffies))
force_quiescent_state(rsp, 1);
local_irq_restore(flags);
}
}
EXPORT_SYMBOL_GPL(call_rcu_bh);
+/**
+ * synchronize_sched - wait until an rcu-sched grace period has elapsed.
+ *
+ * Control will return to the caller some time after a full rcu-sched
+ * grace period has elapsed, in other words after all currently executing
+ * rcu-sched read-side critical sections have completed. These read-side
+ * critical sections are delimited by rcu_read_lock_sched() and
+ * rcu_read_unlock_sched(), and may be nested. Note that preempt_disable(),
+ * local_irq_disable(), and so on may be used in place of
+ * rcu_read_lock_sched().
+ *
+ * This means that all preempt_disable code sequences, including NMI and
+ * hardware-interrupt handlers, in progress on entry will have completed
+ * before this primitive returns. However, this does not guarantee that
+ * softirq handlers will have completed, since in some kernels, these
+ * handlers can run in process context, and can block.
+ *
+ * This primitive provides the guarantees made by the (now removed)
+ * synchronize_kernel() API. In contrast, synchronize_rcu() only
+ * guarantees that rcu_read_lock() sections will have completed.
+ * In "classic RCU", these two guarantees happen to be one and
+ * the same, but can differ in realtime RCU implementations.
+ */
+void synchronize_sched(void)
+{
+ struct rcu_synchronize rcu;
+
+ 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);
+
+/**
+ * synchronize_rcu_bh - wait until an rcu_bh grace period has elapsed.
+ *
+ * Control will return to the caller some time after a full rcu_bh grace
+ * period has elapsed, in other words after all currently executing rcu_bh
+ * read-side critical sections have completed. RCU read-side critical
+ * sections are delimited by rcu_read_lock_bh() and rcu_read_unlock_bh(),
+ * and may be nested.
+ */
+void synchronize_rcu_bh(void)
+{
+ struct rcu_synchronize rcu;
+
+ 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 to see if there is any immediate RCU-related work to be done
* by the current CPU, for the specified type of RCU, returning 1 if so.
*/
static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
{
+ struct rcu_node *rnp = rdp->mynode;
+
rdp->n_rcu_pending++;
/* Check for CPU stalls, if enabled. */
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 another RCU grace period completed? */
- if (ACCESS_ONCE(rsp->completed) != rdp->completed) { /* outside lock */
+ if (ACCESS_ONCE(rnp->completed) != rdp->completed) { /* outside lock */
rdp->n_rp_gp_completed++;
return 1;
}
/* Has a new RCU grace period started? */
- if (ACCESS_ONCE(rsp->gpnum) != rdp->gpnum) { /* outside lock */
+ if (ACCESS_ONCE(rnp->gpnum) != rdp->gpnum) { /* outside lock */
rdp->n_rp_gp_started++;
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 ||
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);
}
/*
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)
/*
* Handle CPU online/offline notification events.
*/
-int __cpuinit rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
+static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
}
/*
+ * 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.
*/
*/
static void __init rcu_init_one(struct rcu_state *rsp)
{
+ 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);
+ 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;
rnp->level = i;
INIT_LIST_HEAD(&rnp->blocked_tasks[0]);
INIT_LIST_HEAD(&rnp->blocked_tasks[1]);
+ INIT_LIST_HEAD(&rnp->blocked_tasks[2]);
+ INIT_LIST_HEAD(&rnp->blocked_tasks[3]);
}
}
- lockdep_set_class(&rcu_get_root(rsp)->lock, &rcu_root_class);
+
+ rnp = rsp->level[NUM_RCU_LVLS - 1];
+ for_each_possible_cpu(i) {
+ while (i > rnp->grphi)
+ rnp++;
+ rsp->rda[i]->mynode = rnp;
+ rcu_boot_init_percpu_data(i, rsp);
+ }
}
/*
#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); \
} \
+ rcu_init_one(rsp); \
} while (0)
-void __init __rcu_init(void)
+void __init rcu_init(void)
{
+ 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 */
RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data);
RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data);
__rcu_init_preempt();
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
+
+ /*
+ * We don't need protection against CPU-hotplug here because
+ * this is called early in boot, before either interrupts
+ * or the scheduler are operational.
+ */
+ cpu_notifier(rcu_cpu_notify, 0);
+ for_each_online_cpu(cpu)
+ rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
+ check_cpu_stall_init();
}
#include "rcutree_plugin.h"
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff