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rcu: Switch ->dynticks to rcu_data structure, remove rcu_dynticks

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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@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-08-03 21:00:38 -07:00
parent 4c5273bf2b
commit dc5a4f2932
4 changed files with 56 additions and 80 deletions
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92
kernel/rcu/tree.c
View File

@ -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);
@ -635,7 +630,7 @@ void rcu_user_enter(void)
/*
* 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.
*
@ -645,7 +640,6 @@ 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.
@ -660,14 +654,14 @@ 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)
@ -742,11 +736,9 @@ 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);
@ -757,7 +749,7 @@ 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);
@ -802,7 +794,7 @@ 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
@ -814,7 +806,6 @@ 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. */
@ -842,7 +833,7 @@ 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();
@ -995,7 +986,7 @@ 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);
@ -1046,7 +1037,7 @@ 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);
@ -3198,9 +3189,8 @@ 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;

35
kernel/rcu/tree.h
View File

@ -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);

6
kernel/rcu/tree_exp.h
View File

@ -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;
}

3
kernel/rcu/tree_plugin.h
View File

@ -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,