#include "rcutree.h"
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-static struct lock_class_key rcu_lock_key;
-struct lockdep_map rcu_lock_map =
- STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
-EXPORT_SYMBOL_GPL(rcu_lock_map);
-#endif
-
/* Data structures. */
#define RCU_STATE_INITIALIZER(name) { \
NUM_RCU_LVL_2, \
NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \
}, \
- .signaled = RCU_SIGNAL_INIT, \
+ .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), \
.n_force_qs = 0, \
.n_force_qs_ngp = 0, \
static int qhimark = 10000; /* If this many pending, ignore blimit. */
static int qlowmark = 100; /* Once only this many pending, use blimit. */
+module_param(blimit, int, 0);
+module_param(qhimark, int, 0);
+module_param(qlowmark, int, 0);
+
static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
static int rcu_pending(int cpu);
long delta;
unsigned long flags;
struct rcu_node *rnp = rcu_get_root(rsp);
- struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1];
- struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES];
/* Only let one CPU complain about others per time interval. */
return;
}
rsp->jiffies_stall = jiffies + RCU_SECONDS_TILL_STALL_RECHECK;
+
+ /*
+ * Now rat on any tasks that got kicked up to the root rcu_node
+ * due to CPU offlining.
+ */
+ rcu_print_task_stall(rnp);
spin_unlock_irqrestore(&rnp->lock, flags);
/* OK, time to rat on our buddy... */
printk(KERN_ERR "INFO: RCU detected CPU stalls:");
- for (; rnp_cur < rnp_end; rnp_cur++) {
+ rcu_for_each_leaf_node(rsp, rnp) {
rcu_print_task_stall(rnp);
- if (rnp_cur->qsmask == 0)
+ if (rnp->qsmask == 0)
continue;
- for (cpu = 0; cpu <= rnp_cur->grphi - rnp_cur->grplo; cpu++)
- if (rnp_cur->qsmask & (1UL << cpu))
- printk(" %d", rnp_cur->grplo + cpu);
+ 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",
smp_processor_id(), (long)(jiffies - rsp->gp_start));
* one corresponding to this CPU, due to the fact that we have
* irqs disabled.
*/
- for (rnp = &rsp->node[0]; rnp < &rsp->node[NUM_RCU_NODES]; rnp++) {
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ rcu_for_each_node_breadth_first(rsp, rnp) {
+ spin_lock(&rnp->lock); /* irqs already disabled. */
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
rnp->gpnum = rsp->gpnum;
- spin_unlock(&rnp->lock); /* irqs already disabled. */
+ spin_unlock(&rnp->lock); /* irqs remain disabled. */
}
+ rnp = rcu_get_root(rsp);
+ 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);
}
{
WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
rsp->completed = rsp->gpnum;
+ rsp->signaled = RCU_GP_IDLE;
rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
}
#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. */
spin_unlock(&rnp->lock); /* irqs remain disabled. */
break;
}
- rcu_preempt_offline_tasks(rsp, rnp, rdp);
+
+ /*
+ * 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;
+
mask = rnp->grpmask;
spin_unlock(&rnp->lock); /* irqs remain disabled. */
rnp = rnp->parent;
} 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.
- */
- rdp_me = rsp->rda[smp_processor_id()];
- if (rdp->nxtlist != NULL) {
- *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)
{
}
* Invoke any RCU callbacks that have made it to the end of their grace
* period. Thottle as specified by rdp->blimit.
*/
-static void rcu_do_batch(struct rcu_data *rdp)
+static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
{
unsigned long flags;
struct rcu_head *next, *list, **tail;
if (rdp->blimit == LONG_MAX && rdp->qlen <= qlowmark)
rdp->blimit = blimit;
+ /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */
+ if (rdp->qlen == 0 && rdp->qlen_last_fqs_check != 0) {
+ rdp->qlen_last_fqs_check = 0;
+ rdp->n_force_qs_snap = rsp->n_force_qs;
+ } else if (rdp->qlen < rdp->qlen_last_fqs_check - qhimark)
+ rdp->qlen_last_fqs_check = rdp->qlen;
+
local_irq_restore(flags);
/* Re-raise the RCU softirq if there are callbacks remaining. */
int cpu;
unsigned long flags;
unsigned long mask;
- struct rcu_node *rnp_cur = rsp->level[NUM_RCU_LVLS - 1];
- struct rcu_node *rnp_end = &rsp->node[NUM_RCU_NODES];
+ struct rcu_node *rnp;
- for (; rnp_cur < rnp_end; rnp_cur++) {
+ rcu_for_each_leaf_node(rsp, rnp) {
mask = 0;
- spin_lock_irqsave(&rnp_cur->lock, flags);
+ spin_lock_irqsave(&rnp->lock, flags);
if (rsp->completed != lastcomp) {
- spin_unlock_irqrestore(&rnp_cur->lock, flags);
+ spin_unlock_irqrestore(&rnp->lock, flags);
return 1;
}
- if (rnp_cur->qsmask == 0) {
- spin_unlock_irqrestore(&rnp_cur->lock, flags);
+ if (rnp->qsmask == 0) {
+ spin_unlock_irqrestore(&rnp->lock, flags);
continue;
}
- cpu = rnp_cur->grplo;
+ cpu = rnp->grplo;
bit = 1;
- for (; cpu <= rnp_cur->grphi; cpu++, bit <<= 1) {
- if ((rnp_cur->qsmask & bit) != 0 && f(rsp->rda[cpu]))
+ for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
+ if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
mask |= bit;
}
if (mask != 0 && rsp->completed == lastcomp) {
- /* cpu_quiet_msk() releases rnp_cur->lock. */
- cpu_quiet_msk(mask, rsp, rnp_cur, flags);
+ /* cpu_quiet_msk() releases rnp->lock. */
+ cpu_quiet_msk(mask, rsp, rnp, flags);
continue;
}
- spin_unlock_irqrestore(&rnp_cur->lock, flags);
+ spin_unlock_irqrestore(&rnp->lock, flags);
}
return 0;
}
}
spin_unlock(&rnp->lock);
switch (signaled) {
+ case RCU_GP_IDLE:
case RCU_GP_INIT:
- break; /* grace period still initializing, ignore. */
+ break; /* grace period idle or initializing, ignore. */
case RCU_SAVE_DYNTICK:
/* Update state, record completion counter. */
spin_lock(&rnp->lock);
- if (lastcomp == rsp->completed) {
+ if (lastcomp == rsp->completed &&
+ rsp->signaled == RCU_SAVE_DYNTICK) {
rsp->signaled = RCU_FORCE_QS;
dyntick_record_completed(rsp, lastcomp);
}
}
/* If there are callbacks ready, invoke them. */
- rcu_do_batch(rdp);
+ rcu_do_batch(rsp, rdp);
}
/*
rcu_start_gp(rsp, nestflag); /* releases rnp_root->lock. */
}
- /* Force the grace period if too many callbacks or too long waiting. */
- if (unlikely(++rdp->qlen > qhimark)) {
+ /*
+ * Force the grace period if too many callbacks or too long waiting.
+ * Enforce hysteresis, and don't invoke force_quiescent_state()
+ * if some other CPU has recently done so. Also, don't bother
+ * invoking force_quiescent_state() if the newly enqueued callback
+ * 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;
- force_quiescent_state(rsp, 0);
+ 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)
force_quiescent_state(rsp, 1);
local_irq_restore(flags);
rcu_preempt_needs_cpu(cpu);
}
+static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};
+static atomic_t rcu_barrier_cpu_count;
+static DEFINE_MUTEX(rcu_barrier_mutex);
+static struct completion rcu_barrier_completion;
+
+static void rcu_barrier_callback(struct rcu_head *notused)
+{
+ if (atomic_dec_and_test(&rcu_barrier_cpu_count))
+ complete(&rcu_barrier_completion);
+}
+
+/*
+ * Called with preemption disabled, and from cross-cpu IRQ context.
+ */
+static void rcu_barrier_func(void *type)
+{
+ int cpu = smp_processor_id();
+ struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu);
+ void (*call_rcu_func)(struct rcu_head *head,
+ void (*func)(struct rcu_head *head));
+
+ atomic_inc(&rcu_barrier_cpu_count);
+ call_rcu_func = type;
+ call_rcu_func(head, rcu_barrier_callback);
+}
+
+/*
+ * Orchestrate the specified type of RCU barrier, waiting for all
+ * RCU callbacks of the specified type to complete.
+ */
+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 mutex to serialize concurrent rcu_barrier() requests. */
+ mutex_lock(&rcu_barrier_mutex);
+ init_completion(&rcu_barrier_completion);
+ /*
+ * Initialize rcu_barrier_cpu_count to 1, then invoke
+ * rcu_barrier_func() on each CPU, so that each CPU also has
+ * incremented rcu_barrier_cpu_count. Only then is it safe to
+ * 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.
+ */
+ 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);
+}
+
+/**
+ * rcu_barrier_bh - Wait until all in-flight call_rcu_bh() callbacks complete.
+ */
+void rcu_barrier_bh(void)
+{
+ _rcu_barrier(&rcu_bh_state, call_rcu_bh);
+}
+EXPORT_SYMBOL_GPL(rcu_barrier_bh);
+
+/**
+ * rcu_barrier_sched - Wait for in-flight call_rcu_sched() callbacks.
+ */
+void rcu_barrier_sched(void)
+{
+ _rcu_barrier(&rcu_sched_state, call_rcu_sched);
+}
+EXPORT_SYMBOL_GPL(rcu_barrier_sched);
+
/*
* Do boot-time initialization of a CPU's per-CPU RCU data.
*/
rdp->beenonline = 1; /* We have now been online. */
rdp->preemptable = preemptable;
rdp->passed_quiesc_completed = lastcomp - 1;
+ 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. */
case CPU_UP_PREPARE_FROZEN:
rcu_online_cpu(cpu);
break;
+ 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.
+ */
+ 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:
case CPU_UP_CANCELED:
cpustride *= rsp->levelspread[i];
rnp = rsp->level[i];
for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
- spin_lock_init(&rnp->lock);
+ if (rnp != rcu_get_root(rsp))
+ spin_lock_init(&rnp->lock);
rnp->gpnum = 0;
rnp->qsmask = 0;
rnp->qsmaskinit = 0;
INIT_LIST_HEAD(&rnp->blocked_tasks[1]);
}
}
+ spin_lock_init(&rcu_get_root(rsp)->lock);
}
/*
*/
#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; \
void __init __rcu_init(void)
{
- int i; /* All used by RCU_INIT_FLAVOR(). */
- int j;
- struct rcu_node *rnp;
-
rcu_bootup_announce();
#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n");
}
#include "rcutree_plugin.h"
-
-module_param(blimit, int, 0);
-module_param(qhimark, int, 0);
-module_param(qlowmark, int, 0);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff