#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] }, \
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, \
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;
+
/*
* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
struct rcu_data *rdp;
rdp = &per_cpu(rcu_sched_data, cpu);
- rdp->passed_quiesc_completed = rdp->completed;
+ rdp->passed_quiesc_completed = rdp->gpnum - 1;
barrier();
rdp->passed_quiesc = 1;
rcu_preempt_note_context_switch(cpu);
struct rcu_data *rdp;
rdp = &per_cpu(rcu_bh_data, cpu);
- rdp->passed_quiesc_completed = rdp->completed;
+ rdp->passed_quiesc_completed = rdp->gpnum - 1;
barrier();
rdp->passed_quiesc = 1;
}
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
struct rcu_node *rnp = rcu_get_root(rsp);
if (!cpu_needs_another_gp(rsp, rdp)) {
- spin_unlock_irqrestore(&rnp->lock, flags);
+ if (rnp->completed == rsp->completed) {
+ spin_unlock_irqrestore(&rnp->lock, flags);
+ return;
+ }
+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
+
+ /*
+ * Propagate new ->completed value to rcu_node structures
+ * so that other CPUs don't have to wait until the start
+ * of the next grace period to process their callbacks.
+ */
+ rcu_for_each_node_breadth_first(rsp, rnp) {
+ spin_lock(&rnp->lock); /* irqs already disabled. */
+ rnp->completed = rsp->completed;
+ 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) {
}
/*
- * 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;
/*
* 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;
rnp = rdp->mynode;
spin_lock_irqsave(&rnp->lock, flags);
- if (lastcomp != ACCESS_ONCE(rsp->completed)) {
+ 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);
*/
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
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;
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)
+ 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
+ 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.
+ */
+ 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);
+ if (need_report & RCU_OFL_TASKS_EXP_GP)
+ rcu_report_exp_rnp(rsp, rnp);
rcu_adopt_orphan_cbs(rsp);
}
rcu_for_each_leaf_node(rsp, rnp) {
mask = 0;
spin_lock_irqsave(&rnp->lock, flags);
- if (rsp->completed != lastcomp) {
+ if (rnp->completed != lastcomp) {
spin_unlock_irqrestore(&rnp->lock, flags);
return 1;
}
if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
mask |= bit;
}
- if (mask != 0 && rsp->completed == lastcomp) {
+ if (mask != 0 && rnp->completed == lastcomp) {
- /* 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);
goto unlock_ret; /* no emergency and done recently. */
rsp->n_force_qs++;
spin_lock(&rnp->lock);
- lastcomp = rsp->completed;
+ lastcomp = rsp->gpnum - 1;
signaled = rsp->signaled;
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. */
/* Update state, record completion counter. */
forcenow = 0;
spin_lock(&rnp->lock);
- if (lastcomp == rsp->completed &&
+ if (lastcomp + 1 == rsp->gpnum &&
+ lastcomp == rsp->completed &&
rsp->signaled == signaled) {
rsp->signaled = RCU_FORCE_QS;
- dyntick_record_completed(rsp, lastcomp);
+ rsp->completed_fqs = lastcomp;
forcenow = signaled == RCU_SAVE_COMPLETED;
}
spin_unlock(&rnp->lock);
case RCU_FORCE_QS:
/* Check dyntick-idle state, send IPI to laggarts. */
- if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),
+ if (rcu_process_dyntick(rsp, rsp->completed_fqs,
rcu_implicit_dynticks_qs))
goto unlock_ret;
}
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_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);
+}
+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_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);
+}
+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. */
}
/* 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;
}
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);
/*
* 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;
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]);
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);
}
/*
} \
} while (0)
-void __init __rcu_init(void)
+void __init rcu_init(void)
{
+ int i;
+
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_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(i)
+ rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)i);
}
#include "rcutree_plugin.h"
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff