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Date: Wed, 29 Aug 2018 16:07:32 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: mingo@...nel.org, jiangshanlai@...il.com, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 07/10] rcu: Switch dyntick nesting counters to rcu_data structure
This commit removes ->dynticks_nesting and ->dynticks_nmi_nesting from
the rcu_dynticks structure and updates the code to access them from the
rcu_data structure.
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/tree.c | 79 +++++++++++++++++++++-------------------
kernel/rcu/tree.h | 2 -
kernel/rcu/tree_plugin.h | 2 +-
3 files changed, 43 insertions(+), 40 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 44f5e0a99e5a..35326d1005eb 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -73,7 +73,10 @@
/* Data structures. */
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data);
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
+ .dynticks_nesting = 1,
+ .dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
+};
struct rcu_state rcu_state = {
.level = { &rcu_state.node[0] },
.gp_state = RCU_GP_IDLE,
@@ -210,8 +213,6 @@ void rcu_softirq_qs(void)
#endif
static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
- .dynticks_nesting = 1,
- .dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
.dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
};
@@ -378,8 +379,8 @@ static void __maybe_unused rcu_momentary_dyntick_idle(void)
*/
static int rcu_is_cpu_rrupt_from_idle(void)
{
- return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 0 &&
- __this_cpu_read(rcu_dynticks.dynticks_nmi_nesting) <= 1;
+ return __this_cpu_read(rcu_data.dynticks_nesting) <= 0 &&
+ __this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 1;
}
#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch. */
@@ -571,27 +572,27 @@ static struct rcu_node *rcu_get_root(void)
*/
static void rcu_eqs_enter(bool user)
{
- struct rcu_data *rdp;
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
struct rcu_dynticks *rdtp;
rdtp = this_cpu_ptr(&rcu_dynticks);
- WARN_ON_ONCE(rdtp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0);
+ 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) &&
- rdtp->dynticks_nesting == 0);
- if (rdtp->dynticks_nesting != 1) {
- rdtp->dynticks_nesting--;
+ rdp->dynticks_nesting == 0);
+ if (rdp->dynticks_nesting != 1) {
+ rdp->dynticks_nesting--;
return;
}
lockdep_assert_irqs_disabled();
- trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0, rdtp->dynticks);
+ trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, rdtp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
rdp = this_cpu_ptr(&rcu_data);
do_nocb_deferred_wakeup(rdp);
rcu_prepare_for_idle();
rcu_preempt_deferred_qs(current);
- WRITE_ONCE(rdtp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
+ WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
rcu_dynticks_eqs_enter();
rcu_dynticks_task_enter();
}
@@ -637,7 +638,7 @@ void rcu_user_enter(void)
* @irq: Is this call from rcu_irq_exit?
*
* If we are returning from the outermost NMI handler that interrupted an
- * RCU-idle period, update rdtp->dynticks and rdtp->dynticks_nmi_nesting
+ * RCU-idle period, update rdtp->dynticks and rdp->dynticks_nmi_nesting
* to let the RCU grace-period handling know that the CPU is back to
* being RCU-idle.
*
@@ -646,30 +647,31 @@ void rcu_user_enter(void)
*/
static __always_inline void rcu_nmi_exit_common(bool irq)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+ struct rcu_dynticks __maybe_unused *rdtp = this_cpu_ptr(&rcu_dynticks);
/*
* Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
* (We are exiting an NMI handler, so RCU better be paying attention
* to us!)
*/
- WARN_ON_ONCE(rdtp->dynticks_nmi_nesting <= 0);
+ WARN_ON_ONCE(rdp->dynticks_nmi_nesting <= 0);
WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
/*
* If the nesting level is not 1, the CPU wasn't RCU-idle, so
* leave it in non-RCU-idle state.
*/
- if (rdtp->dynticks_nmi_nesting != 1) {
- trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, rdtp->dynticks_nmi_nesting - 2, rdtp->dynticks);
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */
- rdtp->dynticks_nmi_nesting - 2);
+ if (rdp->dynticks_nmi_nesting != 1) {
+ trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdtp->dynticks);
+ WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
+ rdp->dynticks_nmi_nesting - 2);
return;
}
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
- trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0, rdtp->dynticks);
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
+ trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, rdtp->dynticks);
+ WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
if (irq)
rcu_prepare_for_idle();
@@ -738,25 +740,27 @@ void rcu_irq_exit_irqson(void)
*/
static void rcu_eqs_exit(bool user)
{
+ struct rcu_data *rdp;
struct rcu_dynticks *rdtp;
long oldval;
lockdep_assert_irqs_disabled();
rdtp = this_cpu_ptr(&rcu_dynticks);
- oldval = rdtp->dynticks_nesting;
+ rdp = this_cpu_ptr(&rcu_data);
+ oldval = rdp->dynticks_nesting;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
if (oldval) {
- rdtp->dynticks_nesting++;
+ rdp->dynticks_nesting++;
return;
}
rcu_dynticks_task_exit();
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
- trace_rcu_dyntick(TPS("End"), rdtp->dynticks_nesting, 1, rdtp->dynticks);
+ trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, rdtp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
- WRITE_ONCE(rdtp->dynticks_nesting, 1);
- WARN_ON_ONCE(rdtp->dynticks_nmi_nesting);
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
+ WRITE_ONCE(rdp->dynticks_nesting, 1);
+ WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
+ WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
}
/**
@@ -798,7 +802,7 @@ void rcu_user_exit(void)
* @irq: Is this call from rcu_irq_enter?
*
* If the CPU was idle from RCU's viewpoint, update rdtp->dynticks and
- * rdtp->dynticks_nmi_nesting to let the RCU grace-period handling know
+ * rdp->dynticks_nmi_nesting to let the RCU grace-period handling know
* that the CPU is active. This implementation permits nested NMIs, as
* long as the nesting level does not overflow an int. (You will probably
* run out of stack space first.)
@@ -808,11 +812,12 @@ void rcu_user_exit(void)
*/
static __always_inline void rcu_nmi_enter_common(bool irq)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+ struct rcu_dynticks __maybe_unused *rdtp = this_cpu_ptr(&rcu_dynticks);
long incby = 2;
/* Complain about underflow. */
- WARN_ON_ONCE(rdtp->dynticks_nmi_nesting < 0);
+ WARN_ON_ONCE(rdp->dynticks_nmi_nesting < 0);
/*
* If idle from RCU viewpoint, atomically increment ->dynticks
@@ -835,10 +840,10 @@ static __always_inline void rcu_nmi_enter_common(bool irq)
incby = 1;
}
trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
- rdtp->dynticks_nmi_nesting,
- rdtp->dynticks_nmi_nesting + incby, rdtp->dynticks);
- WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */
- rdtp->dynticks_nmi_nesting + incby);
+ rdp->dynticks_nmi_nesting,
+ rdp->dynticks_nmi_nesting + incby, rdtp->dynticks);
+ WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
+ rdp->dynticks_nmi_nesting + incby);
barrier();
}
@@ -3193,7 +3198,7 @@ rcu_boot_init_percpu_data(int cpu)
/* Set up local state, ensuring consistent view of global state. */
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
- WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1);
+ WARN_ON_ONCE(rdp->dynticks_nesting != 1);
WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks)));
rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;
@@ -3226,7 +3231,7 @@ int rcutree_prepare_cpu(unsigned int cpu)
if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */
!init_nocb_callback_list(rdp))
rcu_segcblist_init(&rdp->cblist); /* Re-enable callbacks. */
- rdp->dynticks->dynticks_nesting = 1; /* CPU not up, no tearing. */
+ rdp->dynticks_nesting = 1; /* CPU not up, no tearing. */
rcu_dynticks_eqs_online();
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 4c31066ddb94..2e5eec48a94a 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -38,8 +38,6 @@
* Dynticks per-CPU state.
*/
struct rcu_dynticks {
- long dynticks_nesting; /* Track process nesting level. */
- long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */
atomic_t dynticks; /* Even value for idle, else odd. */
};
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 161760957a07..7087ee3e1ea5 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1831,7 +1831,7 @@ static void print_cpu_stall_info(int cpu)
"!."[!delta],
ticks_value, ticks_title,
rcu_dynticks_snap(rdtp) & 0xfff,
- rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,
+ rdp->dynticks_nesting, rdp->dynticks_nmi_nesting,
rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
fast_no_hz);
--
2.17.1
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