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-rw-r--r--kernel/rcu/tree.c123
-rw-r--r--kernel/rcu/tree.h1
2 files changed, 82 insertions, 42 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 6e92bf4337bd..d2cdcada6fe0 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3642,19 +3642,77 @@ static int synchronize_sched_expedited_cpu_stop(void *data)
struct rcu_data *rdp = data;
struct rcu_state *rsp = rdp->rsp;
- /* We are here: If we are last, do the wakeup. */
- rdp->exp_done = true;
- if (atomic_dec_and_test(&rsp->expedited_need_qs))
- wake_up(&rsp->expedited_wq);
+ /* Report the quiescent state. */
+ rcu_report_exp_rdp(rsp, rdp, true);
return 0;
}
+/*
+ * Select the nodes that the upcoming expedited grace period needs
+ * to wait for.
+ */
+static void sync_sched_exp_select_cpus(struct rcu_state *rsp)
+{
+ int cpu;
+ unsigned long flags;
+ unsigned long mask;
+ unsigned long mask_ofl_test;
+ unsigned long mask_ofl_ipi;
+ struct rcu_data *rdp;
+ struct rcu_node *rnp;
+
+ sync_exp_reset_tree(rsp);
+ rcu_for_each_leaf_node(rsp, rnp) {
+ raw_spin_lock_irqsave(&rnp->lock, flags);
+ smp_mb__after_unlock_lock();
+
+ /* Each pass checks a CPU for identity, offline, and idle. */
+ mask_ofl_test = 0;
+ for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) {
+ struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+ struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+
+ if (raw_smp_processor_id() == cpu ||
+ cpu_is_offline(cpu) ||
+ !(atomic_add_return(0, &rdtp->dynticks) & 0x1))
+ mask_ofl_test |= rdp->grpmask;
+ }
+ mask_ofl_ipi = rnp->expmask & ~mask_ofl_test;
+
+ /*
+ * Need to wait for any blocked tasks as well. Note that
+ * additional blocking tasks will also block the expedited
+ * GP until such time as the ->expmask bits are cleared.
+ */
+ if (rcu_preempt_has_tasks(rnp))
+ rnp->exp_tasks = rnp->blkd_tasks.next;
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
+
+ /* IPI the remaining CPUs for expedited quiescent state. */
+ mask = 1;
+ for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
+ if (!(mask_ofl_ipi & mask))
+ continue;
+ rdp = per_cpu_ptr(rsp->rda, cpu);
+ stop_one_cpu_nowait(cpu, synchronize_sched_expedited_cpu_stop,
+ rdp, &rdp->exp_stop_work);
+ mask_ofl_ipi &= ~mask;
+ }
+ /* Report quiescent states for those that went offline. */
+ mask_ofl_test |= mask_ofl_ipi;
+ if (mask_ofl_test)
+ rcu_report_exp_cpu_mult(rsp, rnp, mask_ofl_test, false);
+ }
+}
+
static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
{
int cpu;
unsigned long jiffies_stall;
unsigned long jiffies_start;
- struct rcu_data *rdp;
+ unsigned long mask;
+ struct rcu_node *rnp;
+ struct rcu_node *rnp_root = rcu_get_root(rsp);
int ret;
jiffies_stall = rcu_jiffies_till_stall_check();
@@ -3663,33 +3721,36 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
for (;;) {
ret = wait_event_interruptible_timeout(
rsp->expedited_wq,
- !atomic_read(&rsp->expedited_need_qs),
+ sync_rcu_preempt_exp_done(rnp_root),
jiffies_stall);
if (ret > 0)
return;
if (ret < 0) {
/* Hit a signal, disable CPU stall warnings. */
wait_event(rsp->expedited_wq,
- !atomic_read(&rsp->expedited_need_qs));
+ sync_rcu_preempt_exp_done(rnp_root));
return;
}
pr_err("INFO: %s detected expedited stalls on CPUs: {",
rsp->name);
- for_each_online_cpu(cpu) {
- rdp = per_cpu_ptr(rsp->rda, cpu);
-
- if (rdp->exp_done)
- continue;
- pr_cont(" %d", cpu);
+ rcu_for_each_leaf_node(rsp, rnp) {
+ mask = 1;
+ for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
+ if (!(rnp->expmask & mask))
+ continue;
+ pr_cont(" %d", cpu);
+ }
+ mask <<= 1;
}
pr_cont(" } %lu jiffies s: %lu\n",
jiffies - jiffies_start, rsp->expedited_sequence);
- for_each_online_cpu(cpu) {
- rdp = per_cpu_ptr(rsp->rda, cpu);
-
- if (rdp->exp_done)
- continue;
- dump_cpu_task(cpu);
+ rcu_for_each_leaf_node(rsp, rnp) {
+ mask = 1;
+ for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
+ if (!(rnp->expmask & mask))
+ continue;
+ dump_cpu_task(cpu);
+ }
}
jiffies_stall = 3 * rcu_jiffies_till_stall_check() + 3;
}
@@ -3713,7 +3774,6 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
*/
void synchronize_sched_expedited(void)
{
- int cpu;
unsigned long s;
struct rcu_node *rnp;
struct rcu_state *rsp = &rcu_sched_state;
@@ -3736,27 +3796,8 @@ void synchronize_sched_expedited(void)
}
rcu_exp_gp_seq_start(rsp);
-
- /* Stop each CPU that is online, non-idle, and not us. */
- atomic_set(&rsp->expedited_need_qs, 1); /* Extra count avoids race. */
- for_each_online_cpu(cpu) {
- struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
- struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
-
- rdp->exp_done = false;
-
- /* Skip our CPU and any idle CPUs. */
- if (raw_smp_processor_id() == cpu ||
- !(atomic_add_return(0, &rdtp->dynticks) & 0x1))
- continue;
- atomic_inc(&rsp->expedited_need_qs);
- stop_one_cpu_nowait(cpu, synchronize_sched_expedited_cpu_stop,
- rdp, &rdp->exp_stop_work);
- }
-
- /* Remove extra count and, if necessary, wait for CPUs to stop. */
- if (!atomic_dec_and_test(&rsp->expedited_need_qs))
- synchronize_sched_expedited_wait(rsp);
+ sync_sched_exp_select_cpus(rsp);
+ synchronize_sched_expedited_wait(rsp);
rcu_exp_gp_seq_end(rsp);
mutex_unlock(&rnp->exp_funnel_mutex);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index a57f25ecca58..efe361c764ab 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -383,7 +383,6 @@ struct rcu_data {
struct rcu_head oom_head;
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
struct mutex exp_funnel_mutex;
- bool exp_done; /* Expedited QS for this CPU? */
/* 7) Callback offloading. */
#ifdef CONFIG_RCU_NOCB_CPU
generated by cgit v1.2.3 (git 2.39.1) at 2024-10-13 20:32:28 +0000