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-rw-r--r--kernel/rcu/tree.c437
1 files changed, 311 insertions, 126 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 48d640ca1a05..233165da782f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -91,8 +91,10 @@ static const char *tp_##sname##_varname __used __tracepoint_string = sname##_var
#define RCU_STATE_INITIALIZER(sname, sabbr, cr) \
DEFINE_RCU_TPS(sname) \
+DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, sname##_data); \
struct rcu_state sname##_state = { \
.level = { &sname##_state.node[0] }, \
+ .rda = &sname##_data, \
.call = cr, \
.fqs_state = RCU_GP_IDLE, \
.gpnum = 0UL - 300UL, \
@@ -101,11 +103,9 @@ struct rcu_state sname##_state = { \
.orphan_nxttail = &sname##_state.orphan_nxtlist, \
.orphan_donetail = &sname##_state.orphan_donelist, \
.barrier_mutex = __MUTEX_INITIALIZER(sname##_state.barrier_mutex), \
- .onoff_mutex = __MUTEX_INITIALIZER(sname##_state.onoff_mutex), \
.name = RCU_STATE_NAME(sname), \
.abbr = sabbr, \
-}; \
-DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, sname##_data)
+}
RCU_STATE_INITIALIZER(rcu_sched, 's', call_rcu_sched);
RCU_STATE_INITIALIZER(rcu_bh, 'b', call_rcu_bh);
@@ -152,6 +152,8 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);
*/
static int rcu_scheduler_fully_active __read_mostly;
+static void rcu_init_new_rnp(struct rcu_node *rnp_leaf);
+static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf);
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
static void invoke_rcu_core(void);
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
@@ -160,6 +162,12 @@ static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO;
module_param(kthread_prio, int, 0644);
+/* Delay in jiffies for grace-period initialization delays. */
+static int gp_init_delay = IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_INIT)
+ ? CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY
+ : 0;
+module_param(gp_init_delay, int, 0644);
+
/*
* Track the rcutorture test sequence number and the update version
* number within a given test. The rcutorture_testseq is incremented
@@ -173,6 +181,17 @@ unsigned long rcutorture_testseq;
unsigned long rcutorture_vernum;
/*
+ * Compute the mask of online CPUs for the specified rcu_node structure.
+ * This will not be stable unless the rcu_node structure's ->lock is
+ * held, but the bit corresponding to the current CPU will be stable
+ * in most contexts.
+ */
+unsigned long rcu_rnp_online_cpus(struct rcu_node *rnp)
+{
+ return ACCESS_ONCE(rnp->qsmaskinitnext);
+}
+
+/*
* Return true if an RCU grace period is in progress. The ACCESS_ONCE()s
* permit this function to be invoked without holding the root rcu_node
* structure's ->lock, but of course results can be subject to change.
@@ -292,10 +311,10 @@ void rcu_note_context_switch(void)
EXPORT_SYMBOL_GPL(rcu_note_context_switch);
/*
- * Register a quiesecent state for all RCU flavors. If there is an
+ * Register a quiescent state for all RCU flavors. If there is an
* emergency, invoke rcu_momentary_dyntick_idle() to do a heavy-weight
* dyntick-idle quiescent state visible to other CPUs (but only for those
- * RCU flavors in desparate need of a quiescent state, which will normally
+ * RCU flavors in desperate need of a quiescent state, which will normally
* be none of them). Either way, do a lightweight quiescent state for
* all RCU flavors.
*/
@@ -410,6 +429,15 @@ void rcu_bh_force_quiescent_state(void)
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);
+}
+EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
+
+/*
* Show the state of the grace-period kthreads.
*/
void show_rcu_gp_kthreads(void)
@@ -483,15 +511,6 @@ void rcutorture_record_progress(unsigned long vernum)
EXPORT_SYMBOL_GPL(rcutorture_record_progress);
/*
- * Force a quiescent state for RCU-sched.
- */
-void rcu_sched_force_quiescent_state(void)
-{
- force_quiescent_state(&rcu_sched_state);
-}
-EXPORT_SYMBOL_GPL(rcu_sched_force_quiescent_state);
-
-/*
* Does the CPU have callbacks ready to be invoked?
*/
static int
@@ -954,7 +973,7 @@ bool rcu_lockdep_current_cpu_online(void)
preempt_disable();
rdp = this_cpu_ptr(&rcu_sched_data);
rnp = rdp->mynode;
- ret = (rdp->grpmask & rnp->qsmaskinit) ||
+ ret = (rdp->grpmask & rcu_rnp_online_cpus(rnp)) ||
!rcu_scheduler_fully_active;
preempt_enable();
return ret;
@@ -1196,9 +1215,10 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
} else {
j = jiffies;
gpa = ACCESS_ONCE(rsp->gp_activity);
- pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld\n",
+ pr_err("All QSes seen, last %s kthread activity %ld (%ld-%ld), jiffies_till_next_fqs=%ld, root ->qsmask %#lx\n",
rsp->name, j - gpa, j, gpa,
- jiffies_till_next_fqs);
+ jiffies_till_next_fqs,
+ rcu_get_root(rsp)->qsmask);
/* In this case, the current CPU might be at fault. */
sched_show_task(current);
}
@@ -1328,20 +1348,30 @@ void rcu_cpu_stall_reset(void)
}
/*
- * Initialize the specified rcu_data structure's callback list to empty.
+ * Initialize the specified rcu_data structure's default callback list
+ * to empty. The default callback list is the one that is not used by
+ * no-callbacks CPUs.
*/
-static void init_callback_list(struct rcu_data *rdp)
+static void init_default_callback_list(struct rcu_data *rdp)
{
int i;
- if (init_nocb_callback_list(rdp))
- return;
rdp->nxtlist = NULL;
for (i = 0; i < RCU_NEXT_SIZE; i++)
rdp->nxttail[i] = &rdp->nxtlist;
}
/*
+ * Initialize the specified rcu_data structure's callback list to empty.
+ */
+static void init_callback_list(struct rcu_data *rdp)
+{
+ if (init_nocb_callback_list(rdp))
+ return;
+ init_default_callback_list(rdp);
+}
+
+/*
* Determine the value that ->completed will have at the end of the
* next subsequent grace period. This is used to tag callbacks so that
* a CPU can invoke callbacks in a timely fashion even if that CPU has
@@ -1703,11 +1733,11 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp)
*/
static int rcu_gp_init(struct rcu_state *rsp)
{
+ unsigned long oldmask;
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);
ACCESS_ONCE(rsp->gp_activity) = jiffies;
- rcu_bind_gp_kthread();
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
if (!ACCESS_ONCE(rsp->gp_flags)) {
@@ -1733,9 +1763,54 @@ static int rcu_gp_init(struct rcu_state *rsp)
trace_rcu_grace_period(rsp->name, rsp->gpnum, TPS("start"));
raw_spin_unlock_irq(&rnp->lock);
- /* Exclude any concurrent CPU-hotplug operations. */
- mutex_lock(&rsp->onoff_mutex);
- smp_mb__after_unlock_lock(); /* ->gpnum increment before GP! */
+ /*
+ * Apply per-leaf buffered online and offline operations to the
+ * rcu_node tree. Note that this new grace period need not wait
+ * for subsequent online CPUs, and that quiescent-state forcing
+ * will handle subsequent offline CPUs.
+ */
+ rcu_for_each_leaf_node(rsp, rnp) {
+ raw_spin_lock_irq(&rnp->lock);
+ smp_mb__after_unlock_lock();
+ if (rnp->qsmaskinit == rnp->qsmaskinitnext &&
+ !rnp->wait_blkd_tasks) {
+ /* Nothing to do on this leaf rcu_node structure. */
+ raw_spin_unlock_irq(&rnp->lock);
+ continue;
+ }
+
+ /* Record old state, apply changes to ->qsmaskinit field. */
+ oldmask = rnp->qsmaskinit;
+ rnp->qsmaskinit = rnp->qsmaskinitnext;
+
+ /* If zero-ness of ->qsmaskinit changed, propagate up tree. */
+ if (!oldmask != !rnp->qsmaskinit) {
+ if (!oldmask) /* First online CPU for this rcu_node. */
+ rcu_init_new_rnp(rnp);
+ else if (rcu_preempt_has_tasks(rnp)) /* blocked tasks */
+ rnp->wait_blkd_tasks = true;
+ else /* Last offline CPU and can propagate. */
+ rcu_cleanup_dead_rnp(rnp);
+ }
+
+ /*
+ * If all waited-on tasks from prior grace period are
+ * done, and if all this rcu_node structure's CPUs are
+ * still offline, propagate up the rcu_node tree and
+ * clear ->wait_blkd_tasks. Otherwise, if one of this
+ * rcu_node structure's CPUs has since come back online,
+ * simply clear ->wait_blkd_tasks (but rcu_cleanup_dead_rnp()
+ * checks for this, so just call it unconditionally).
+ */
+ if (rnp->wait_blkd_tasks &&
+ (!rcu_preempt_has_tasks(rnp) ||
+ rnp->qsmaskinit)) {
+ rnp->wait_blkd_tasks = false;
+ rcu_cleanup_dead_rnp(rnp);
+ }
+
+ raw_spin_unlock_irq(&rnp->lock);
+ }
/*
* Set the quiescent-state-needed bits in all the rcu_node
@@ -1757,8 +1832,8 @@ static int rcu_gp_init(struct rcu_state *rsp)
rcu_preempt_check_blocked_tasks(rnp);
rnp->qsmask = rnp->qsmaskinit;
ACCESS_ONCE(rnp->gpnum) = rsp->gpnum;
- WARN_ON_ONCE(rnp->completed != rsp->completed);
- ACCESS_ONCE(rnp->completed) = rsp->completed;
+ if (WARN_ON_ONCE(rnp->completed != rsp->completed))
+ ACCESS_ONCE(rnp->completed) = rsp->completed;
if (rnp == rdp->mynode)
(void)__note_gp_changes(rsp, rnp, rdp);
rcu_preempt_boost_start_gp(rnp);
@@ -1768,9 +1843,12 @@ static int rcu_gp_init(struct rcu_state *rsp)
raw_spin_unlock_irq(&rnp->lock);
cond_resched_rcu_qs();
ACCESS_ONCE(rsp->gp_activity) = jiffies;
+ if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_INIT) &&
+ gp_init_delay > 0 &&
+ !(rsp->gpnum % (rcu_num_nodes * 10)))
+ schedule_timeout_uninterruptible(gp_init_delay);
}
- mutex_unlock(&rsp->onoff_mutex);
return 1;
}
@@ -1798,7 +1876,7 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
fqs_state = RCU_FORCE_QS;
} else {
/* Handle dyntick-idle and offline CPUs. */
- isidle = false;
+ isidle = true;
force_qs_rnp(rsp, rcu_implicit_dynticks_qs, &isidle, &maxj);
}
/* Clear flag to prevent immediate re-entry. */
@@ -1852,6 +1930,8 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
rcu_for_each_node_breadth_first(rsp, rnp) {
raw_spin_lock_irq(&rnp->lock);
smp_mb__after_unlock_lock();
+ WARN_ON_ONCE(rcu_preempt_blocked_readers_cgp(rnp));
+ WARN_ON_ONCE(rnp->qsmask);
ACCESS_ONCE(rnp->completed) = rsp->gpnum;
rdp = this_cpu_ptr(rsp->rda);
if (rnp == rdp->mynode)
@@ -1895,6 +1975,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
struct rcu_state *rsp = arg;
struct rcu_node *rnp = rcu_get_root(rsp);
+ rcu_bind_gp_kthread();
for (;;) {
/* Handle grace-period start. */
@@ -2062,25 +2143,32 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
* 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.
+ * must be represented by the same rcu_node structure (which need not be a
+ * leaf rcu_node structure, though it often will be). The gps parameter
+ * is the grace-period snapshot, which means that the quiescent states
+ * are valid only if rnp->gpnum is equal to gps. That structure's lock
+ * must be held upon entry, and it is released before return.
*/
static void
rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
- struct rcu_node *rnp, unsigned long flags)
+ struct rcu_node *rnp, unsigned long gps, unsigned long flags)
__releases(rnp->lock)
{
+ unsigned long oldmask = 0;
struct rcu_node *rnp_c;
/* Walk up the rcu_node hierarchy. */
for (;;) {
- if (!(rnp->qsmask & mask)) {
+ if (!(rnp->qsmask & mask) || rnp->gpnum != gps) {
- /* Our bit has already been cleared, so done. */
+ /*
+ * Our bit has already been cleared, or the
+ * relevant grace period is already over, so done.
+ */
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
+ WARN_ON_ONCE(oldmask); /* Any child must be all zeroed! */
rnp->qsmask &= ~mask;
trace_rcu_quiescent_state_report(rsp->name, rnp->gpnum,
mask, rnp->qsmask, rnp->level,
@@ -2104,7 +2192,7 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
rnp = rnp->parent;
raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
- WARN_ON_ONCE(rnp_c->qsmask);
+ oldmask = rnp_c->qsmask;
}
/*
@@ -2116,6 +2204,46 @@ rcu_report_qs_rnp(unsigned long mask, struct rcu_state *rsp,
}
/*
+ * Record a quiescent state for all tasks that were previously queued
+ * on the specified rcu_node structure and that were blocking the current
+ * RCU grace period. The caller must hold the specified rnp->lock with
+ * irqs disabled, and this lock is released upon return, but irqs remain
+ * disabled.
+ */
+static void rcu_report_unblock_qs_rnp(struct rcu_state *rsp,
+ struct rcu_node *rnp, unsigned long flags)
+ __releases(rnp->lock)
+{
+ unsigned long gps;
+ unsigned long mask;
+ struct rcu_node *rnp_p;
+
+ if (rcu_state_p == &rcu_sched_state || rsp != rcu_state_p ||
+ rnp->qsmask != 0 || rcu_preempt_blocked_readers_cgp(rnp)) {
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+ return; /* Still need more quiescent states! */
+ }
+
+ rnp_p = rnp->parent;
+ if (rnp_p == NULL) {
+ /*
+ * Only one rcu_node structure in the tree, so don't
+ * try to report up to its nonexistent parent!
+ */
+ rcu_report_qs_rsp(rsp, flags);
+ return;
+ }
+
+ /* Report up the rest of the hierarchy, tracking current ->gpnum. */
+ gps = rnp->gpnum;
+ mask = rnp->grpmask;
+ raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
+ raw_spin_lock(&rnp_p->lock); /* irqs already disabled. */
+ smp_mb__after_unlock_lock();
+ rcu_report_qs_rnp(mask, rsp, rnp_p, gps, flags);
+}
+
+/*
* 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
@@ -2163,7 +2291,8 @@ rcu_report_qs_rdp(int cpu, struct rcu_state *rsp, struct rcu_data *rdp)
*/
needwake = rcu_accelerate_cbs(rsp, rnp, rdp);
- rcu_report_qs_rnp(mask, rsp, rnp, flags); /* rlses rnp->lock */
+ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags);
+ /* ^^^ Released rnp->lock */
if (needwake)
rcu_gp_kthread_wake(rsp);
}
@@ -2256,8 +2385,12 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
rsp->orphan_donetail = rdp->nxttail[RCU_DONE_TAIL];
}
- /* Finally, initialize the rcu_data structure's list to empty. */
+ /*
+ * Finally, initialize the rcu_data structure's list to empty and
+ * disallow further callbacks on this CPU.
+ */
init_callback_list(rdp);
+ rdp->nxttail[RCU_NEXT_TAIL] = NULL;
}
/*
@@ -2355,6 +2488,7 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
raw_spin_lock(&rnp->lock); /* irqs already disabled. */
smp_mb__after_unlock_lock(); /* GP memory ordering. */
rnp->qsmaskinit &= ~mask;
+ rnp->qsmask &= ~mask;
if (rnp->qsmaskinit) {
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
return;
@@ -2364,6 +2498,26 @@ static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
}
/*
+ * The CPU is exiting the idle loop into the arch_cpu_idle_dead()
+ * function. We now remove it from the rcu_node tree's ->qsmaskinit
+ * bit masks.
+ */
+static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
+{
+ unsigned long flags;
+ unsigned long mask;
+ struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+ struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
+
+ /* Remove outgoing CPU from mask in the leaf rcu_node structure. */
+ mask = rdp->grpmask;
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ smp_mb__after_unlock_lock(); /* Enforce GP memory-order guarantee. */
+ rnp->qsmaskinitnext &= ~mask;
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+}
+
+/*
* The CPU has been completely removed, and some other CPU is reporting
* this fact from process context. Do the remainder of the cleanup,
* including orphaning the outgoing CPU's RCU callbacks, and also
@@ -2379,29 +2533,15 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
/* Adjust any no-longer-needed kthreads. */
rcu_boost_kthread_setaffinity(rnp, -1);
- /* Exclude any attempts to start a new grace period. */
- mutex_lock(&rsp->onoff_mutex);
- raw_spin_lock_irqsave(&rsp->orphan_lock, flags);
-
/* Orphan the dead CPU's callbacks, and adopt them if appropriate. */
+ raw_spin_lock_irqsave(&rsp->orphan_lock, flags);
rcu_send_cbs_to_orphanage(cpu, rsp, rnp, rdp);
rcu_adopt_orphan_cbs(rsp, flags);
raw_spin_unlock_irqrestore(&rsp->orphan_lock, flags);
- /* Remove outgoing CPU from mask in the leaf rcu_node structure. */
- raw_spin_lock_irqsave(&rnp->lock, flags);
- smp_mb__after_unlock_lock(); /* Enforce GP memory-order guarantee. */
- rnp->qsmaskinit &= ~rdp->grpmask;
- if (rnp->qsmaskinit == 0 && !rcu_preempt_has_tasks(rnp))
- rcu_cleanup_dead_rnp(rnp);
- rcu_report_qs_rnp(rdp->grpmask, rsp, rnp, flags); /* Rlses rnp->lock. */
WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",
cpu, rdp->qlen, rdp->nxtlist);
- init_callback_list(rdp);
- /* Disallow further callbacks on this CPU. */
- rdp->nxttail[RCU_NEXT_TAIL] = NULL;
- mutex_unlock(&rsp->onoff_mutex);
}
#else /* #ifdef CONFIG_HOTPLUG_CPU */
@@ -2414,6 +2554,10 @@ static void __maybe_unused rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf)
{
}
+static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
+{
+}
+
static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
{
}
@@ -2589,26 +2733,47 @@ static void force_qs_rnp(struct rcu_state *rsp,
return;
}
if (rnp->qsmask == 0) {
- rcu_initiate_boost(rnp, flags); /* releases rnp->lock */
- continue;
+ if (rcu_state_p == &rcu_sched_state ||
+ rsp != rcu_state_p ||
+ rcu_preempt_blocked_readers_cgp(rnp)) {
+ /*
+ * No point in scanning bits because they
+ * are all zero. But we might need to
+ * priority-boost blocked readers.
+ */
+ rcu_initiate_boost(rnp, flags);
+ /* rcu_initiate_boost() releases rnp->lock */
+ continue;
+ }
+ if (rnp->parent &&
+ (rnp->parent->qsmask & rnp->grpmask)) {
+ /*
+ * Race between grace-period
+ * initialization and task exiting RCU
+ * read-side critical section: Report.
+ */
+ rcu_report_unblock_qs_rnp(rsp, rnp, flags);
+ /* rcu_report_unblock_qs_rnp() rlses ->lock */
+ continue;
+ }
}
cpu = rnp->grplo;
bit = 1;
for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
if ((rnp->qsmask & bit) != 0) {
- if ((rnp->qsmaskinit & bit) != 0)
- *isidle = false;
+ if ((rnp->qsmaskinit & bit) == 0)
+ *isidle = false; /* Pending hotplug. */
if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
mask |= bit;
}
}
if (mask != 0) {
-
- /* rcu_report_qs_rnp() releases rnp->lock. */
- rcu_report_qs_rnp(mask, rsp, rnp, flags);
- continue;
+ /* Idle/offline CPUs, report (releases rnp->lock. */
+ rcu_report_qs_rnp(mask, rsp, rnp, rnp->gpnum, flags);
+ } else {
+ /* Nothing to do here, so just drop the lock. */
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
}
@@ -2741,7 +2906,7 @@ static void __call_rcu_core(struct rcu_state *rsp, struct rcu_data *rdp,
* If called from an extended quiescent state, invoke the RCU
* core in order to force a re-evaluation of RCU's idleness.
*/
- if (!rcu_is_watching() && cpu_online(smp_processor_id()))
+ if (!rcu_is_watching())
invoke_rcu_core();
/* If interrupts were disabled or CPU offline, don't invoke RCU core. */
@@ -2827,11 +2992,22 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
if (cpu != -1)
rdp = per_cpu_ptr(rsp->rda, cpu);
- offline = !__call_rcu_nocb(rdp, head, lazy, flags);
- WARN_ON_ONCE(offline);
- /* _call_rcu() is illegal on offline CPU; leak the callback. */
- local_irq_restore(flags);
- return;
+ if (likely(rdp->mynode)) {
+ /* Post-boot, so this should be for a no-CBs CPU. */
+ offline = !__call_rcu_nocb(rdp, head, lazy, flags);
+ WARN_ON_ONCE(offline);
+ /* Offline CPU, _call_rcu() illegal, leak callback. */
+ local_irq_restore(flags);
+ return;
+ }
+ /*
+ * Very early boot, before rcu_init(). Initialize if needed
+ * and then drop through to queue the callback.
+ */
+ BUG_ON(cpu != -1);
+ WARN_ON_ONCE(!rcu_is_watching());
+ if (!likely(rdp->nxtlist))
+ init_default_callback_list(rdp);
}
ACCESS_ONCE(rdp->qlen) = rdp->qlen + 1;
if (lazy)
@@ -2954,7 +3130,7 @@ void synchronize_sched(void)
"Illegal synchronize_sched() in RCU-sched read-side critical section");
if (rcu_blocking_is_gp())
return;
- if (rcu_expedited)
+ if (rcu_gp_is_expedited())
synchronize_sched_expedited();
else
wait_rcu_gp(call_rcu_sched);
@@ -2981,7 +3157,7 @@ void synchronize_rcu_bh(void)
"Illegal synchronize_rcu_bh() in RCU-bh read-side critical section");
if (rcu_blocking_is_gp())
return;
- if (rcu_expedited)
+ if (rcu_gp_is_expedited())
synchronize_rcu_bh_expedited();
else
wait_rcu_gp(call_rcu_bh);
@@ -3518,6 +3694,28 @@ void rcu_barrier_sched(void)
EXPORT_SYMBOL_GPL(rcu_barrier_sched);
/*
+ * Propagate ->qsinitmask bits up the rcu_node tree to account for the
+ * first CPU in a given leaf rcu_node structure coming online. The caller
+ * must hold the corresponding leaf rcu_node ->lock with interrrupts
+ * disabled.
+ */
+static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
+{
+ long mask;
+ struct rcu_node *rnp = rnp_leaf;
+
+ for (;;) {
+ mask = rnp->grpmask;
+ rnp = rnp->parent;
+ if (rnp == NULL)
+ return;
+ raw_spin_lock(&rnp->lock); /* Interrupts already disabled. */
+ rnp->qsmaskinit |= mask;
+ raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */
+ }
+}
+
+/*
* Do boot-time initialization of a CPU's per-CPU RCU data.
*/
static void __init
@@ -3553,49 +3751,37 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
struct rcu_node *rnp = rcu_get_root(rsp);
- /* Exclude new grace periods. */
- mutex_lock(&rsp->onoff_mutex);
-
/* Set up local state, ensuring consistent view of global state. */
raw_spin_lock_irqsave(&rnp->lock, flags);
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;
- init_callback_list(rdp); /* Re-enable callbacks on this CPU. */
+ if (!rdp->nxtlist)
+ init_callback_list(rdp); /* Re-enable callbacks on this CPU. */
rdp->dynticks->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
rcu_sysidle_init_percpu_data(rdp->dynticks);
atomic_set(&rdp->dynticks->dynticks,
(atomic_read(&rdp->dynticks->dynticks) & ~0x1) + 1);
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
- /* Add CPU to rcu_node bitmasks. */
+ /*
+ * Add CPU to leaf rcu_node pending-online bitmask. Any needed
+ * propagation up the rcu_node tree will happen at the beginning
+ * of the next grace period.
+ */
rnp = rdp->mynode;
mask = rdp->grpmask;
- do {
- /* Exclude any attempts to start a new GP on small systems. */
- raw_spin_lock(&rnp->lock); /* irqs already disabled. */
- rnp->qsmaskinit |= mask;
- mask = rnp->grpmask;
- if (rnp == rdp->mynode) {
- /*
- * If there is a grace period in progress, we will
- * set up to wait for it next time we run the
- * RCU core code.
- */
- rdp->gpnum = rnp->completed;
- rdp->completed = rnp->completed;
- rdp->passed_quiesce = 0;
- rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
- rdp->qs_pending = 0;
- trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
- }
- raw_spin_unlock(&rnp->lock); /* irqs already disabled. */
- rnp = rnp->parent;
- } while (rnp != NULL && !(rnp->qsmaskinit & mask));
- local_irq_restore(flags);
-
- mutex_unlock(&rsp->onoff_mutex);
+ raw_spin_lock(&rnp->lock); /* irqs already disabled. */
+ smp_mb__after_unlock_lock();
+ rnp->qsmaskinitnext |= mask;
+ rdp->gpnum = rnp->completed; /* Make CPU later note any new GP. */
+ rdp->completed = rnp->completed;
+ rdp->passed_quiesce = false;
+ rdp->rcu_qs_ctr_snap = __this_cpu_read(rcu_qs_ctr);
+ rdp->qs_pending = false;
+ trace_rcu_grace_period(rsp->name, rdp->gpnum, TPS("cpuonl"));
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
static void rcu_prepare_cpu(int cpu)
@@ -3609,15 +3795,14 @@ static void rcu_prepare_cpu(int cpu)
/*
* Handle CPU online/offline notification events.
*/
-static int rcu_cpu_notify(struct notifier_block *self,
- unsigned long action, void *hcpu)
+int rcu_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
struct rcu_data *rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
struct rcu_node *rnp = rdp->mynode;
struct rcu_state *rsp;
- trace_rcu_utilization(TPS("Start CPU hotplug"));
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
@@ -3637,6 +3822,11 @@ static int rcu_cpu_notify(struct notifier_block *self,
for_each_rcu_flavor(rsp)
rcu_cleanup_dying_cpu(rsp);
break;
+ case CPU_DYING_IDLE:
+ for_each_rcu_flavor(rsp) {
+ rcu_cleanup_dying_idle_cpu(cpu, rsp);
+ }
+ break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
case CPU_UP_CANCELED:
@@ -3649,7 +3839,6 @@ static int rcu_cpu_notify(struct notifier_block *self,
default:
break;
}
- trace_rcu_utilization(TPS("End CPU hotplug"));
return NOTIFY_OK;
}
@@ -3660,11 +3849,12 @@ static int rcu_pm_notify(struct notifier_block *self,
case PM_HIBERNATION_PREPARE:
case PM_SUSPEND_PREPARE:
if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */
- rcu_expedited = 1;
+ rcu_expedite_gp();
break;
case PM_POST_HIBERNATION:
case PM_POST_SUSPEND:
- rcu_expedited = 0;
+ if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */
+ rcu_unexpedite_gp();
break;
default:
break;
@@ -3734,30 +3924,26 @@ void rcu_scheduler_starting(void)
* Compute the per-level fanout, either using the exact fanout specified
* or balancing the tree, depending on CONFIG_RCU_FANOUT_EXACT.
*/
-#ifdef CONFIG_RCU_FANOUT_EXACT
-static void __init rcu_init_levelspread(struct rcu_state *rsp)
-{
- int i;
-
- rsp->levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
- for (i = rcu_num_lvls - 2; i >= 0; i--)
- rsp->levelspread[i] = CONFIG_RCU_FANOUT;
-}
-#else /* #ifdef CONFIG_RCU_FANOUT_EXACT */
static void __init rcu_init_levelspread(struct rcu_state *rsp)
{
- int ccur;
- int cprv;
int i;
- cprv = nr_cpu_ids;
- for (i = rcu_num_lvls - 1; i >= 0; i--) {
- ccur = rsp->levelcnt[i];
- rsp->levelspread[i] = (cprv + ccur - 1) / ccur;
- cprv = ccur;
+ if (IS_ENABLED(CONFIG_RCU_FANOUT_EXACT)) {
+ rsp->levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
+ for (i = rcu_num_lvls - 2; i >= 0; i--)
+ rsp->levelspread[i] = CONFIG_RCU_FANOUT;
+ } else {
+ int ccur;
+ int cprv;
+
+ cprv = nr_cpu_ids;
+ for (i = rcu_num_lvls - 1; i >= 0; i--) {
+ ccur = rsp->levelcnt[i];
+ rsp->levelspread[i] = (cprv + ccur - 1) / ccur;
+ cprv = ccur;
+ }
}
}
-#endif /* #else #ifdef CONFIG_RCU_FANOUT_EXACT */
/*
* Helper function for rcu_init() that initializes one rcu_state structure.
@@ -3833,7 +4019,6 @@ static void __init rcu_init_one(struct rcu_state *rsp,
}
}
- rsp->rda = rda;
init_waitqueue_head(&rsp->gp_wq);
rnp = rsp->level[rcu_num_lvls - 1];
for_each_possible_cpu(i) {
@@ -3926,6 +4111,8 @@ void __init rcu_init(void)
{
int cpu;
+ rcu_early_boot_tests();
+
rcu_bootup_announce();
rcu_init_geometry();
rcu_init_one(&rcu_bh_state, &rcu_bh_data);
@@ -3942,8 +4129,6 @@ void __init rcu_init(void)
pm_notifier(rcu_pm_notify, 0);
for_each_online_cpu(cpu)
rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
-
- rcu_early_boot_tests();
}
#include "tree_plugin.h"