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Message-Id: <20180829230735.10256-8-paulmck@linux.vnet.ibm.com>
Date: Wed, 29 Aug 2018 16:07:33 -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 08/10] rcu: Switch ->dynticks to rcu_data structure, remove rcu_dynticks
This commit move ->dynticks from the rcu_dynticks structure to the
rcu_data structure, replacing the field of the same name. It also updates
the code to access ->dynticks from the rcu_data structure and to use the
rcu_data structure rather than following to now-gone ->dynticks field
to the now-gone rcu_dynticks structure. While in the area, this commit
also fixes up comments.
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
kernel/rcu/tree.c | 92 ++++++++++++++++++----------------------
kernel/rcu/tree.h | 35 ++++++---------
kernel/rcu/tree_exp.h | 6 +--
kernel/rcu/tree_plugin.h | 3 +-
4 files changed, 56 insertions(+), 80 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 35326d1005eb..ad09707d99ee 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -73,9 +73,20 @@
/* Data structures. */
+/*
+ * Steal a bit from the bottom of ->dynticks for idle entry/exit
+ * control. Initially this is for TLB flushing.
+ */
+#define RCU_DYNTICK_CTRL_MASK 0x1
+#define RCU_DYNTICK_CTRL_CTR (RCU_DYNTICK_CTRL_MASK + 1)
+#ifndef rcu_eqs_special_exit
+#define rcu_eqs_special_exit() do { } while (0)
+#endif
+
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {
.dynticks_nesting = 1,
.dynticks_nmi_nesting = DYNTICK_IRQ_NONIDLE,
+ .dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
};
struct rcu_state rcu_state = {
.level = { &rcu_state.node[0] },
@@ -202,27 +213,13 @@ void rcu_softirq_qs(void)
rcu_preempt_deferred_qs(current);
}
-/*
- * Steal a bit from the bottom of ->dynticks for idle entry/exit
- * control. Initially this is for TLB flushing.
- */
-#define RCU_DYNTICK_CTRL_MASK 0x1
-#define RCU_DYNTICK_CTRL_CTR (RCU_DYNTICK_CTRL_MASK + 1)
-#ifndef rcu_eqs_special_exit
-#define rcu_eqs_special_exit() do { } while (0)
-#endif
-
-static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = {
- .dynticks = ATOMIC_INIT(RCU_DYNTICK_CTRL_CTR),
-};
-
/*
* Record entry into an extended quiescent state. This is only to be
* called when not already in an extended quiescent state.
*/
static void rcu_dynticks_eqs_enter(void)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
int seq;
/*
@@ -230,7 +227,7 @@ static void rcu_dynticks_eqs_enter(void)
* critical sections, and we also must force ordering with the
* next idle sojourn.
*/
- seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdtp->dynticks);
+ seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
/* Better be in an extended quiescent state! */
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
(seq & RCU_DYNTICK_CTRL_CTR));
@@ -245,7 +242,7 @@ static void rcu_dynticks_eqs_enter(void)
*/
static void rcu_dynticks_eqs_exit(void)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
int seq;
/*
@@ -253,11 +250,11 @@ static void rcu_dynticks_eqs_exit(void)
* and we also must force ordering with the next RCU read-side
* critical section.
*/
- seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdtp->dynticks);
+ seq = atomic_add_return(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
!(seq & RCU_DYNTICK_CTRL_CTR));
if (seq & RCU_DYNTICK_CTRL_MASK) {
- atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdtp->dynticks);
+ atomic_andnot(RCU_DYNTICK_CTRL_MASK, &rdp->dynticks);
smp_mb__after_atomic(); /* _exit after clearing mask. */
/* Prefer duplicate flushes to losing a flush. */
rcu_eqs_special_exit();
@@ -276,11 +273,11 @@ static void rcu_dynticks_eqs_exit(void)
*/
static void rcu_dynticks_eqs_online(void)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
- if (atomic_read(&rdtp->dynticks) & RCU_DYNTICK_CTRL_CTR)
+ if (atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR)
return;
- atomic_add(RCU_DYNTICK_CTRL_CTR, &rdtp->dynticks);
+ atomic_add(RCU_DYNTICK_CTRL_CTR, &rdp->dynticks);
}
/*
@@ -290,18 +287,18 @@ static void rcu_dynticks_eqs_online(void)
*/
bool rcu_dynticks_curr_cpu_in_eqs(void)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
- return !(atomic_read(&rdtp->dynticks) & RCU_DYNTICK_CTRL_CTR);
+ return !(atomic_read(&rdp->dynticks) & RCU_DYNTICK_CTRL_CTR);
}
/*
* Snapshot the ->dynticks counter with full ordering so as to allow
* stable comparison of this counter with past and future snapshots.
*/
-int rcu_dynticks_snap(struct rcu_dynticks *rdtp)
+int rcu_dynticks_snap(struct rcu_data *rdp)
{
- int snap = atomic_add_return(0, &rdtp->dynticks);
+ int snap = atomic_add_return(0, &rdp->dynticks);
return snap & ~RCU_DYNTICK_CTRL_MASK;
}
@@ -316,13 +313,13 @@ static bool rcu_dynticks_in_eqs(int snap)
}
/*
- * Return true if the CPU corresponding to the specified rcu_dynticks
+ * Return true if the CPU corresponding to the specified rcu_data
* structure has spent some time in an extended quiescent state since
* rcu_dynticks_snap() returned the specified snapshot.
*/
-static bool rcu_dynticks_in_eqs_since(struct rcu_dynticks *rdtp, int snap)
+static bool rcu_dynticks_in_eqs_since(struct rcu_data *rdp, int snap)
{
- return snap != rcu_dynticks_snap(rdtp);
+ return snap != rcu_dynticks_snap(rdp);
}
/*
@@ -336,14 +333,14 @@ bool rcu_eqs_special_set(int cpu)
{
int old;
int new;
- struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
+ struct rcu_data *rdp = &per_cpu(rcu_data, cpu);
do {
- old = atomic_read(&rdtp->dynticks);
+ old = atomic_read(&rdp->dynticks);
if (old & RCU_DYNTICK_CTRL_CTR)
return false;
new = old | RCU_DYNTICK_CTRL_MASK;
- } while (atomic_cmpxchg(&rdtp->dynticks, old, new) != old);
+ } while (atomic_cmpxchg(&rdp->dynticks, old, new) != old);
return true;
}
@@ -360,11 +357,11 @@ bool rcu_eqs_special_set(int cpu)
*/
static void __maybe_unused rcu_momentary_dyntick_idle(void)
{
- struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
int special;
raw_cpu_write(rcu_data.rcu_need_heavy_qs, false);
- special = atomic_add_return(2 * RCU_DYNTICK_CTRL_CTR, &rdtp->dynticks);
+ special = atomic_add_return(2 * RCU_DYNTICK_CTRL_CTR,
+ &this_cpu_ptr(&rcu_data)->dynticks);
/* It is illegal to call this from idle state. */
WARN_ON_ONCE(!(special & RCU_DYNTICK_CTRL_CTR));
rcu_preempt_deferred_qs(current);
@@ -573,9 +570,7 @@ static struct rcu_node *rcu_get_root(void)
static void rcu_eqs_enter(bool user)
{
struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
- struct rcu_dynticks *rdtp;
- rdtp = this_cpu_ptr(&rcu_dynticks);
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) &&
@@ -586,7 +581,7 @@ static void rcu_eqs_enter(bool user)
}
lockdep_assert_irqs_disabled();
- trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, rdtp->dynticks);
+ trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, rdp->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);
@@ -638,7 +633,7 @@ 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 rdp->dynticks_nmi_nesting
+ * RCU-idle period, update rdp->dynticks and rdp->dynticks_nmi_nesting
* to let the RCU grace-period handling know that the CPU is back to
* being RCU-idle.
*
@@ -648,7 +643,6 @@ void rcu_user_enter(void)
static __always_inline void rcu_nmi_exit_common(bool irq)
{
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.
@@ -663,14 +657,14 @@ static __always_inline void rcu_nmi_exit_common(bool irq)
* leave it in non-RCU-idle state.
*/
if (rdp->dynticks_nmi_nesting != 1) {
- trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdtp->dynticks);
+ trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdp->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"), rdp->dynticks_nmi_nesting, 0, rdtp->dynticks);
+ trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, rdp->dynticks);
WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
if (irq)
@@ -741,11 +735,9 @@ 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);
rdp = this_cpu_ptr(&rcu_data);
oldval = rdp->dynticks_nesting;
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
@@ -756,7 +748,7 @@ static void rcu_eqs_exit(bool user)
rcu_dynticks_task_exit();
rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle();
- trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, rdtp->dynticks);
+ trace_rcu_dyntick(TPS("End"), rdp->dynticks_nesting, 1, rdp->dynticks);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
WRITE_ONCE(rdp->dynticks_nesting, 1);
WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
@@ -801,7 +793,7 @@ void rcu_user_exit(void)
* rcu_nmi_enter_common - inform RCU of entry to NMI context
* @irq: Is this call from rcu_irq_enter?
*
- * If the CPU was idle from RCU's viewpoint, update rdtp->dynticks and
+ * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and
* 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
@@ -813,7 +805,6 @@ void rcu_user_exit(void)
static __always_inline void rcu_nmi_enter_common(bool irq)
{
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. */
@@ -841,7 +832,7 @@ static __always_inline void rcu_nmi_enter_common(bool irq)
}
trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
rdp->dynticks_nmi_nesting,
- rdp->dynticks_nmi_nesting + incby, rdtp->dynticks);
+ rdp->dynticks_nmi_nesting + incby, rdp->dynticks);
WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
rdp->dynticks_nmi_nesting + incby);
barrier();
@@ -994,7 +985,7 @@ static void rcu_gpnum_ovf(struct rcu_node *rnp, struct rcu_data *rdp)
*/
static int dyntick_save_progress_counter(struct rcu_data *rdp)
{
- rdp->dynticks_snap = rcu_dynticks_snap(rdp->dynticks);
+ rdp->dynticks_snap = rcu_dynticks_snap(rdp);
if (rcu_dynticks_in_eqs(rdp->dynticks_snap)) {
trace_rcu_fqs(rcu_state.name, rdp->gp_seq, rdp->cpu, TPS("dti"));
rcu_gpnum_ovf(rdp->mynode, rdp);
@@ -1045,7 +1036,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
* read-side critical section that started before the beginning
* of the current RCU grace period.
*/
- if (rcu_dynticks_in_eqs_since(rdp->dynticks, rdp->dynticks_snap)) {
+ if (rcu_dynticks_in_eqs_since(rdp, rdp->dynticks_snap)) {
trace_rcu_fqs(rcu_state.name, rdp->gp_seq, rdp->cpu, TPS("dti"));
rdp->dynticks_fqs++;
rcu_gpnum_ovf(rnp, rdp);
@@ -3197,9 +3188,8 @@ 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_nesting != 1);
- WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp->dynticks)));
+ WARN_ON_ONCE(rcu_dynticks_in_eqs(rcu_dynticks_snap(rdp)));
rdp->rcu_ofl_gp_seq = rcu_state.gp_seq;
rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;
rdp->rcu_onl_gp_seq = rcu_state.gp_seq;
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 2e5eec48a94a..af8681fec23b 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -34,13 +34,6 @@
#include "rcu_segcblist.h"
-/*
- * Dynticks per-CPU state.
- */
-struct rcu_dynticks {
- atomic_t dynticks; /* Even value for idle, else odd. */
-};
-
/* Communicate arguments to a workqueue handler. */
struct rcu_exp_work {
smp_call_func_t rew_func;
@@ -194,24 +187,20 @@ struct rcu_data {
long blimit; /* Upper limit on a processed batch */
/* 3) dynticks interface. */
- struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
int dynticks_snap; /* Per-GP tracking for 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. */
- bool rcu_need_heavy_qs; /* GP old, need heavy quiescent state. */
- bool rcu_urgent_qs; /* GP old need light quiescent state. */
+ 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. */
+ bool rcu_need_heavy_qs; /* GP old, so heavy quiescent state! */
+ bool rcu_urgent_qs; /* GP old need light quiescent state. */
#ifdef CONFIG_RCU_FAST_NO_HZ
- bool all_lazy; /* Are all CPU's CBs lazy? */
- unsigned long nonlazy_posted;
- /* # times non-lazy CBs posted to CPU. */
+ bool all_lazy; /* Are all CPU's CBs lazy? */
+ unsigned long nonlazy_posted; /* # times non-lazy CB posted to CPU. */
unsigned long nonlazy_posted_snap;
- /* idle-period nonlazy_posted snapshot. */
- unsigned long last_accelerate;
- /* Last jiffy CBs were accelerated. */
- unsigned long last_advance_all;
- /* Last jiffy CBs were all advanced. */
- int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
+ /* Nonlazy_posted snapshot. */
+ unsigned long last_accelerate; /* Last jiffy CBs were accelerated. */
+ unsigned long last_advance_all; /* Last jiffy CBs were all advanced. */
+ int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
@@ -426,7 +415,7 @@ extern struct rcu_state rcu_bh_state;
extern struct rcu_state rcu_preempt_state;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
-int rcu_dynticks_snap(struct rcu_dynticks *rdtp);
+int rcu_dynticks_snap(struct rcu_data *rdp);
#ifdef CONFIG_RCU_BOOST
DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index 11387fcd4d85..8d18c1014e2b 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -360,14 +360,13 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
for_each_leaf_node_cpu_mask(rnp, cpu, rnp->expmask) {
unsigned long mask = leaf_node_cpu_bit(rnp, cpu);
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
- struct rcu_dynticks *rdtp = per_cpu_ptr(&rcu_dynticks, cpu);
int snap;
if (raw_smp_processor_id() == cpu ||
!(rnp->qsmaskinitnext & mask)) {
mask_ofl_test |= mask;
} else {
- snap = rcu_dynticks_snap(rdtp);
+ snap = rcu_dynticks_snap(rdp);
if (rcu_dynticks_in_eqs(snap))
mask_ofl_test |= mask;
else
@@ -393,8 +392,7 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
if (!(mask_ofl_ipi & mask))
continue;
retry_ipi:
- if (rcu_dynticks_in_eqs_since(rdp->dynticks,
- rdp->exp_dynticks_snap)) {
+ if (rcu_dynticks_in_eqs_since(rdp, rdp->exp_dynticks_snap)) {
mask_ofl_test |= mask;
continue;
}
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 7087ee3e1ea5..05915e536336 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1802,7 +1802,6 @@ static void print_cpu_stall_info(int cpu)
unsigned long delta;
char fast_no_hz[72];
struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
- struct rcu_dynticks *rdtp = rdp->dynticks;
char *ticks_title;
unsigned long ticks_value;
@@ -1830,7 +1829,7 @@ static void print_cpu_stall_info(int cpu)
rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
"!."[!delta],
ticks_value, ticks_title,
- rcu_dynticks_snap(rdtp) & 0xfff,
+ rcu_dynticks_snap(rdp) & 0xfff,
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,
--
2.17.1
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