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-rw-r--r--kernel/rcutree.c493
1 files changed, 342 insertions, 151 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 705f02ac743..53ae9598f79 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -46,20 +46,24 @@
#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_node_class[NUM_RCU_LVLS];
+
#define RCU_STATE_INITIALIZER(name) { \
.level = { &name.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_SIGNAL_INIT, \
+ .signaled = RCU_GP_IDLE, \
.gpnum = -300, \
.completed = -300, \
.onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \
@@ -77,6 +81,8 @@ DEFINE_PER_CPU(struct rcu_data, rcu_sched_data);
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
@@ -98,7 +104,7 @@ void rcu_sched_qs(int cpu)
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);
@@ -109,7 +115,7 @@ void rcu_bh_qs(int 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;
}
@@ -335,28 +341,9 @@ void rcu_irq_exit(void)
set_need_resched();
}
-/*
- * Record the specified "completed" value, which is later used to validate
- * dynticks counter manipulations. Specify "rsp->completed - 1" to
- * unconditionally invalidate any future dynticks manipulations (which is
- * useful at the beginning of a grace period).
- */
-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
-{
- rsp->dynticks_completed = 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->dynticks_completed;
-}
-
-/*
* Snapshot the specified CPU's dynticks counter so that we can later
* credit them with an implicit quiescent state. Return 1 if this CPU
* is in dynticks idle mode, which is an extended quiescent state.
@@ -419,24 +406,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
#else /* #ifdef CONFIG_NO_HZ */
-static void dyntick_record_completed(struct rcu_state *rsp, long comp)
-{
-}
-
#ifdef CONFIG_SMP
-/*
- * If there are no dynticks, then the only way that a CPU can passively
- * be in a quiescent state is to be offline. Unlike dynticks idle, which
- * is a point in time during the prior (already finished) grace period,
- * an offline CPU is always in a quiescent state, and thus can be
- * unconditionally applied. So just return the current value of completed.
- */
-static long dyntick_recall_completed(struct rcu_state *rsp)
-{
- return rsp->completed;
-}
-
static int dyntick_save_progress_counter(struct rcu_data *rdp)
{
return 0;
@@ -553,13 +524,33 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
/*
* Update CPU-local rcu_data state to record the newly noticed grace period.
* This is used both when we started the grace period and when we notice
- * that someone else started the grace period.
+ * that someone else started the grace period. The caller must hold the
+ * ->lock of the leaf rcu_node structure corresponding to the current CPU,
+ * and must have irqs disabled.
*/
+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;
+ rdp->gpnum = rnp->gpnum;
+ }
+}
+
static void note_new_gpnum(struct rcu_state *rsp, struct rcu_data *rdp)
{
- rdp->qs_pending = 1;
- rdp->passed_quiesc = 0;
- rdp->gpnum = rsp->gpnum;
+ unsigned long flags;
+ struct rcu_node *rnp;
+
+ 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. */
+ local_irq_restore(flags);
+ return;
+ }
+ __note_new_gpnum(rsp, rnp, rdp);
+ spin_unlock_irqrestore(&rnp->lock, flags);
}
/*
@@ -583,6 +574,79 @@ check_for_new_grace_period(struct rcu_state *rsp, struct rcu_data *rdp)
}
/*
+ * Advance this CPU's callbacks, but only if the current grace period
+ * has ended. This may be called only from the CPU to whom the rdp
+ * belongs. In addition, the corresponding leaf rcu_node structure's
+ * ->lock must be held by the caller, with irqs disabled.
+ */
+static void
+__rcu_process_gp_end(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
+{
+ /* Did another grace period end? */
+ if (rdp->completed != rnp->completed) {
+
+ /* Advance callbacks. No harm if list empty. */
+ rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
+ rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
+ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+
+ /* Remember that we saw this grace-period completion. */
+ rdp->completed = rnp->completed;
+ }
+}
+
+/*
+ * Advance this CPU's callbacks, but only if the current grace period
+ * has ended. This may be called only from the CPU to whom the rdp
+ * belongs.
+ */
+static void
+rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
+{
+ unsigned long flags;
+ struct rcu_node *rnp;
+
+ 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. */
+ local_irq_restore(flags);
+ return;
+ }
+ __rcu_process_gp_end(rsp, rnp, rdp);
+ spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+/*
+ * Do per-CPU grace-period initialization for running CPU. The caller
+ * must hold the lock of the leaf rcu_node structure corresponding to
+ * this CPU.
+ */
+static void
+rcu_start_gp_per_cpu(struct rcu_state *rsp, struct rcu_node *rnp, struct rcu_data *rdp)
+{
+ /* Prior grace period ended, so advance callbacks for current CPU. */
+ __rcu_process_gp_end(rsp, rnp, rdp);
+
+ /*
+ * Because this CPU just now started the new grace period, we know
+ * that all of its callbacks will be covered by this upcoming grace
+ * period, even the ones that were registered arbitrarily recently.
+ * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL.
+ *
+ * Other CPUs cannot be sure exactly when the grace period started.
+ * Therefore, their recently registered callbacks must pass through
+ * an additional RCU_NEXT_READY stage, so that they will be handled
+ * by the next RCU grace period.
+ */
+ rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+ rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
+
+ /* Set state so that this CPU will detect the next quiescent state. */
+ __note_new_gpnum(rsp, rnp, rdp);
+}
+
+/*
* Start a new RCU grace period if warranted, re-initializing the hierarchy
* in preparation for detecting the next grace period. The caller must hold
* the root node's ->lock, which is released before return. Hard irqs must
@@ -596,7 +660,23 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
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;
}
@@ -606,29 +686,15 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
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);
- note_new_gpnum(rsp, rdp);
-
- /*
- * Because this CPU just now started the new grace period, we know
- * that all of its callbacks will be covered by this upcoming grace
- * period, even the ones that were registered arbitrarily recently.
- * Therefore, advance all outstanding callbacks to RCU_WAIT_TAIL.
- *
- * Other CPUs cannot be sure exactly when the grace period started.
- * Therefore, their recently registered callbacks must pass through
- * an additional RCU_NEXT_READY stage, so that they will be handled
- * by the next RCU grace period.
- */
- rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
- rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
/* Special-case the common single-level case. */
if (NUM_RCU_NODES == 1) {
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
rnp->gpnum = rsp->gpnum;
+ 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);
return;
}
@@ -657,69 +723,50 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
* irqs disabled.
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
- spin_lock(&rnp->lock); /* irqs already disabled. */
+ 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. */
+ rnp->completed = rsp->completed;
+ if (rnp == rdp->mynode)
+ rcu_start_gp_per_cpu(rsp, rnp, rdp);
+ 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);
}
/*
- * Advance this CPU's callbacks, but only if the current grace period
- * has ended. This may be called only from the CPU to whom the rdp
- * belongs.
- */
-static void
-rcu_process_gp_end(struct rcu_state *rsp, struct rcu_data *rdp)
-{
- long completed_snap;
- unsigned long flags;
-
- local_irq_save(flags);
- completed_snap = ACCESS_ONCE(rsp->completed); /* outside of lock. */
-
- /* Did another grace period end? */
- if (rdp->completed != completed_snap) {
-
- /* Advance callbacks. No harm if list empty. */
- rdp->nxttail[RCU_DONE_TAIL] = rdp->nxttail[RCU_WAIT_TAIL];
- rdp->nxttail[RCU_WAIT_TAIL] = rdp->nxttail[RCU_NEXT_READY_TAIL];
- rdp->nxttail[RCU_NEXT_READY_TAIL] = rdp->nxttail[RCU_NEXT_TAIL];
-
- /* Remember that we saw this grace-period completion. */
- rdp->completed = completed_snap;
- }
- local_irq_restore(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));
rsp->completed = rsp->gpnum;
- rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]);
+ rsp->signaled = RCU_GP_IDLE;
rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */
}
/*
- * 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;
@@ -755,21 +802,23 @@ cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp, struct rcu_node *rnp,
/*
* 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;
@@ -777,15 +826,15 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
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);
@@ -803,7 +852,7 @@ cpu_quiet(int cpu, struct rcu_state *rsp, struct rcu_data *rdp, long lastcomp)
*/
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 */
}
}
@@ -834,8 +883,11 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
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
@@ -895,8 +947,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
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;
@@ -910,17 +962,32 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
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;
}
- rcu_preempt_offline_tasks(rsp, rnp, rdp);
+ 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);
}
@@ -958,7 +1025,7 @@ 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;
@@ -1011,6 +1078,13 @@ static void rcu_do_batch(struct rcu_data *rdp)
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. */
@@ -1085,7 +1159,7 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
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;
}
@@ -1099,10 +1173,10 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp,
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);
@@ -1120,6 +1194,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
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. */
@@ -1132,19 +1207,20 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
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. */
}
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:
@@ -1155,20 +1231,29 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed)
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) {
+ 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);
- break;
+ if (!forcenow)
+ break;
+ /* fall into next case. */
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;
@@ -1224,7 +1309,7 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
}
/* If there are callbacks ready, invoke them. */
- rcu_do_batch(rdp);
+ rcu_do_batch(rsp, rdp);
}
/*
@@ -1288,10 +1373,20 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
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);
@@ -1315,6 +1410,68 @@ void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
}
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.
@@ -1324,6 +1481,8 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
*/
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. */
@@ -1348,13 +1507,13 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp)
}
/* 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;
}
@@ -1397,6 +1556,21 @@ int rcu_needs_cpu(int cpu)
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);
@@ -1508,21 +1682,18 @@ static void __cpuinit
rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
{
unsigned long flags;
- long lastcomp;
unsigned long mask;
struct rcu_data *rdp = 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);
- lastcomp = rsp->completed;
- rdp->completed = lastcomp;
- rdp->gpnum = lastcomp;
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->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. */
@@ -1542,6 +1713,11 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
spin_lock(&rnp->lock); /* irqs already disabled. */
rnp->qsmaskinit |= mask;
mask = rnp->grpmask;
+ if (rnp == rdp->mynode) {
+ rdp->gpnum = rnp->completed; /* if GP in progress... */
+ rdp->completed = rnp->completed;
+ rdp->passed_quiesc_completed = rnp->completed - 1;
+ }
spin_unlock(&rnp->lock); /* irqs already disabled. */
rnp = rnp->parent;
} while (rnp != NULL && !(rnp->qsmaskinit & mask));
@@ -1559,8 +1735,8 @@ 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;
@@ -1647,8 +1823,8 @@ static void __init rcu_init_one(struct rcu_state *rsp)
cpustride *= rsp->levelspread[i];
rnp = rsp->level[i];
for (j = 0; j < rsp->levelcnt[i]; j++, rnp++) {
- if (rnp != rcu_get_root(rsp))
- spin_lock_init(&rnp->lock);
+ spin_lock_init(&rnp->lock);
+ lockdep_set_class(&rnp->lock, &rcu_node_class[i]);
rnp->gpnum = 0;
rnp->qsmask = 0;
rnp->qsmaskinit = 0;
@@ -1669,9 +1845,10 @@ static void __init rcu_init_one(struct rcu_state *rsp)
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]);
}
}
- spin_lock_init(&rcu_get_root(rsp)->lock);
}
/*
@@ -1697,16 +1874,30 @@ do { \
} \
} 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"