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Date: Tue, 3 May 2022 12:00:45 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Phil Auld <pauld@...hat.com>,
Alex Belits <abelits@...vell.com>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
Xiongfeng Wang <wangxiongfeng2@...wei.com>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Thomas Gleixner <tglx@...utronix.de>,
Yu Liao <liaoyu15@...wei.com>,
Boqun Feng <boqun.feng@...il.com>,
"Paul E . McKenney" <paulmck@...nel.org>,
Marcelo Tosatti <mtosatti@...hat.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Uladzislau Rezki <uladzislau.rezki@...y.com>,
Joel Fernandes <joel@...lfernandes.org>
Subject: [PATCH 15/21] rcu/context_tracking: Move dynticks_nesting to context tracking
The RCU eqs tracking is going to be performed by the context tracking
subsystem. The related nesting counters thus need to be moved to the
context tracking structure.
Acked-by: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@...cinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@...y.com>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Nicolas Saenz Julienne <nsaenz@...nel.org>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc: Yu Liao<liaoyu15@...wei.com>
Cc: Phil Auld <pauld@...hat.com>
Cc: Paul Gortmaker<paul.gortmaker@...driver.com>
Cc: Alex Belits <abelits@...vell.com>
---
include/linux/context_tracking_state.h | 12 ++++++++++
kernel/context_tracking.c | 1 +
kernel/rcu/tree.c | 31 +++++++++++++-------------
kernel/rcu/tree.h | 1 -
kernel/rcu/tree_stall.h | 2 +-
5 files changed, 30 insertions(+), 17 deletions(-)
diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
index 014dc431521b..cd3a09fb0aea 100644
--- a/include/linux/context_tracking_state.h
+++ b/include/linux/context_tracking_state.h
@@ -24,6 +24,7 @@ struct context_tracking {
} state;
#endif
atomic_t dynticks; /* Even value for idle, else odd. */
+ long dynticks_nesting; /* Track process nesting level. */
};
#ifdef CONFIG_CONTEXT_TRACKING
@@ -45,6 +46,17 @@ static __always_inline int ct_dynticks_cpu_acquire(int cpu)
struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
return atomic_read_acquire(&ct->state);
}
+
+static __always_inline long ct_dynticks_nesting(void)
+{
+ return __this_cpu_read(context_tracking.dynticks_nesting);
+}
+
+static __always_inline long ct_dynticks_nesting_cpu(int cpu)
+{
+ struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
+ return ct->dynticks_nesting;
+}
#endif
#ifdef CONFIG_CONTEXT_TRACKING_USER
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 20be30c24723..ae86fab4eab5 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -250,6 +250,7 @@ void __init context_tracking_init(void)
#endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */
DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
+ .dynticks_nesting = 1,
.dynticks = ATOMIC_INIT(1),
};
EXPORT_SYMBOL_GPL(context_tracking);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7667186731e3..826946b39943 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -75,7 +75,6 @@
/* Data structures. */
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
- .dynticks_nesting = 1,
.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
#ifdef CONFIG_RCU_NOCB_CPU
.cblist.flags = SEGCBLIST_RCU_CORE,
@@ -436,7 +435,7 @@ static int rcu_is_cpu_rrupt_from_idle(void)
lockdep_assert_irqs_disabled();
/* Check for counter underflows */
- RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0,
+ RCU_LOCKDEP_WARN(ct_dynticks_nesting() < 0,
"RCU dynticks_nesting counter underflow!");
RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 0,
"RCU dynticks_nmi_nesting counter underflow/zero!");
@@ -452,7 +451,7 @@ static int rcu_is_cpu_rrupt_from_idle(void)
WARN_ON_ONCE(!nesting && !is_idle_task(current));
/* Does CPU appear to be idle from an RCU standpoint? */
- return __this_cpu_read(rcu_data.dynticks_nesting) == 0;
+ return ct_dynticks_nesting() == 0;
}
#define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1000 : 10)
@@ -619,16 +618,16 @@ static noinstr void rcu_eqs_enter(bool user)
WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
- rdp->dynticks_nesting == 0);
- if (rdp->dynticks_nesting != 1) {
+ ct_dynticks_nesting() == 0);
+ if (ct_dynticks_nesting() != 1) {
// RCU will still be watching, so just do accounting and leave.
- rdp->dynticks_nesting--;
+ ct->dynticks_nesting--;
return;
}
lockdep_assert_irqs_disabled();
instrumentation_begin();
- trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, ct_dynticks());
+ trace_rcu_dyntick(TPS("Start"), ct_dynticks_nesting(), 0, ct_dynticks());
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
rcu_preempt_deferred_qs(current);
@@ -636,7 +635,7 @@ static noinstr void rcu_eqs_enter(bool user)
instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
instrumentation_end();
- WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
+ WRITE_ONCE(ct->dynticks_nesting, 0); /* Avoid irq-access tearing. */
// RCU is watching here ...
rcu_dynticks_eqs_enter();
// ... but is no longer watching here.
@@ -793,7 +792,7 @@ void rcu_irq_exit_check_preempt(void)
{
lockdep_assert_irqs_disabled();
- RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) <= 0,
+ RCU_LOCKDEP_WARN(ct_dynticks_nesting() <= 0,
"RCU dynticks_nesting counter underflow/zero!");
RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nmi_nesting) !=
DYNTICK_IRQ_NONIDLE,
@@ -819,11 +818,11 @@ static void noinstr rcu_eqs_exit(bool user)
lockdep_assert_irqs_disabled();
rdp = this_cpu_ptr(&rcu_data);
- oldval = rdp->dynticks_nesting;
+ oldval = ct_dynticks_nesting();
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
if (oldval) {
// RCU was already watching, so just do accounting and leave.
- rdp->dynticks_nesting++;
+ ct->dynticks_nesting++;
return;
}
rcu_dynticks_task_exit();
@@ -835,9 +834,9 @@ static void noinstr rcu_eqs_exit(bool user)
// instrumentation for the noinstr rcu_dynticks_eqs_exit()
instrument_atomic_write(&ct->dynticks, sizeof(ct->dynticks));
- trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, ct_dynticks());
+ trace_rcu_dyntick(TPS("End"), ct_dynticks_nesting(), 1, ct_dynticks());
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
- WRITE_ONCE(rdp->dynticks_nesting, 1);
+ WRITE_ONCE(ct->dynticks_nesting, 1);
WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
instrumentation_end();
@@ -4229,12 +4228,13 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
static void __init
rcu_boot_init_percpu_data(int cpu)
{
+ struct context_tracking *ct = this_cpu_ptr(&context_tracking);
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
/* Set up local state, ensuring consistent view of global state. */
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
INIT_WORK(&rdp->strict_work, strict_work_handler);
- WARN_ON_ONCE(rdp->dynticks_nesting != 1);
+ WARN_ON_ONCE(ct->dynticks_nesting != 1);
WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(cpu)));
rdp->barrier_seq_snap = rcu_state.barrier_sequence;
rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
@@ -4259,6 +4259,7 @@ rcu_boot_init_percpu_data(int cpu)
int rcutree_prepare_cpu(unsigned int cpu)
{
unsigned long flags;
+ struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
struct rcu_node *rnp = rcu_get_root();
@@ -4267,7 +4268,7 @@ int rcutree_prepare_cpu(unsigned int cpu)
rdp->qlen_last_fqs_check = 0;
rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
rdp->blimit = blimit;
- rdp->dynticks_nesting = 1; /* CPU not up, no tearing. */
+ ct->dynticks_nesting = 1; /* CPU not up, no tearing. */
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
/*
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 55a6b2191d26..26400b511c5b 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -191,7 +191,6 @@ struct rcu_data {
/* 3) dynticks interface. */
int dynticks_snap; /* Per-GP tracking for dynticks. */
- long dynticks_nesting; /* Track process nesting level. */
long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */
bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */
bool rcu_urgent_qs; /* GP old need light quiescent state. */
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 05f5d7e820d0..0235c03c8642 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -477,7 +477,7 @@ static void print_cpu_stall_info(int cpu)
"!."[!delta],
ticks_value, ticks_title,
rcu_dynticks_snap(cpu) & 0xfff,
- rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
+ ct_dynticks_nesting_cpu(cpu), rdp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
rcuc_starved ? buf : "",
--
2.25.1
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