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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@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2018-08-03 21:00:38 -07:00
parent 2dba13f0b6
commit 4c5273bf2b
3 changed files with 43 additions and 40 deletions
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79
kernel/rcu/tree.c
View File

@ -73,7 +73,10 @@
/* Data structures. */ /* 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 = { struct rcu_state rcu_state = {
.level = { &rcu_state.node[0] }, .level = { &rcu_state.node[0] },
.gp_state = RCU_GP_IDLE, .gp_state = RCU_GP_IDLE,
@ -210,8 +213,6 @@ void rcu_softirq_qs(void)
#endif #endif
static DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { 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), .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) static int rcu_is_cpu_rrupt_from_idle(void)
{ {
return __this_cpu_read(rcu_dynticks.dynticks_nesting) <= 0 && return __this_cpu_read(rcu_data.dynticks_nesting) <= 0 &&
__this_cpu_read(rcu_dynticks.dynticks_nmi_nesting) <= 1; __this_cpu_read(rcu_data.dynticks_nmi_nesting) <= 1;
} }
#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch. */ #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) static void rcu_eqs_enter(bool user)
{ {
struct rcu_data *rdp; struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
struct rcu_dynticks *rdtp; struct rcu_dynticks *rdtp;
rdtp = this_cpu_ptr(&rcu_dynticks); rdtp = this_cpu_ptr(&rcu_dynticks);
WARN_ON_ONCE(rdtp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE); WARN_ON_ONCE(rdp->dynticks_nmi_nesting != DYNTICK_IRQ_NONIDLE);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0);
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
rdtp->dynticks_nesting == 0); rdp->dynticks_nesting == 0);
if (rdtp->dynticks_nesting != 1) { if (rdp->dynticks_nesting != 1) {
rdtp->dynticks_nesting--; rdp->dynticks_nesting--;
return; return;
} }
lockdep_assert_irqs_disabled(); 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)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
rdp = this_cpu_ptr(&rcu_data); rdp = this_cpu_ptr(&rcu_data);
do_nocb_deferred_wakeup(rdp); do_nocb_deferred_wakeup(rdp);
rcu_prepare_for_idle(); rcu_prepare_for_idle();
rcu_preempt_deferred_qs(current); 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_eqs_enter();
rcu_dynticks_task_enter(); rcu_dynticks_task_enter();
} }
@ -634,7 +635,7 @@ void rcu_user_enter(void)
/* /*
* If we are returning from the outermost NMI handler that interrupted an * 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 * to let the RCU grace-period handling know that the CPU is back to
* being RCU-idle. * being RCU-idle.
* *
@ -643,30 +644,31 @@ void rcu_user_enter(void)
*/ */
static __always_inline void rcu_nmi_exit_common(bool irq) 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. * Check for ->dynticks_nmi_nesting underflow and bad ->dynticks.
* (We are exiting an NMI handler, so RCU better be paying attention * (We are exiting an NMI handler, so RCU better be paying attention
* to us!) * 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()); WARN_ON_ONCE(rcu_dynticks_curr_cpu_in_eqs());
/* /*
* If the nesting level is not 1, the CPU wasn't RCU-idle, so * If the nesting level is not 1, the CPU wasn't RCU-idle, so
* leave it in non-RCU-idle state. * leave it in non-RCU-idle state.
*/ */
if (rdtp->dynticks_nmi_nesting != 1) { if (rdp->dynticks_nmi_nesting != 1) {
trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nmi_nesting, rdtp->dynticks_nmi_nesting - 2, rdtp->dynticks); trace_rcu_dyntick(TPS("--="), rdp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting - 2, rdtp->dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* No store tearing. */ WRITE_ONCE(rdp->dynticks_nmi_nesting, /* No store tearing. */
rdtp->dynticks_nmi_nesting - 2); rdp->dynticks_nmi_nesting - 2);
return; return;
} }
/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */ /* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
trace_rcu_dyntick(TPS("Startirq"), rdtp->dynticks_nmi_nesting, 0, rdtp->dynticks); trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, rdtp->dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */
if (irq) if (irq)
rcu_prepare_for_idle(); rcu_prepare_for_idle();
@ -739,25 +741,27 @@ void rcu_irq_exit_irqson(void)
*/ */
static void rcu_eqs_exit(bool user) static void rcu_eqs_exit(bool user)
{ {
struct rcu_data *rdp;
struct rcu_dynticks *rdtp; struct rcu_dynticks *rdtp;
long oldval; long oldval;
lockdep_assert_irqs_disabled(); lockdep_assert_irqs_disabled();
rdtp = this_cpu_ptr(&rcu_dynticks); 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); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && oldval < 0);
if (oldval) { if (oldval) {
rdtp->dynticks_nesting++; rdp->dynticks_nesting++;
return; return;
} }
rcu_dynticks_task_exit(); rcu_dynticks_task_exit();
rcu_dynticks_eqs_exit(); rcu_dynticks_eqs_exit();
rcu_cleanup_after_idle(); 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)); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
WRITE_ONCE(rdtp->dynticks_nesting, 1); WRITE_ONCE(rdp->dynticks_nesting, 1);
WARN_ON_ONCE(rdtp->dynticks_nmi_nesting); WARN_ON_ONCE(rdp->dynticks_nmi_nesting);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE); WRITE_ONCE(rdp->dynticks_nmi_nesting, DYNTICK_IRQ_NONIDLE);
} }
/** /**
@ -799,7 +803,7 @@ void rcu_user_exit(void)
* @irq: Is this call from rcu_irq_enter? * @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 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 * that the CPU is active. This implementation permits nested NMIs, as
* long as the nesting level does not overflow an int. (You will probably * long as the nesting level does not overflow an int. (You will probably
* run out of stack space first.) * run out of stack space first.)
@ -809,11 +813,12 @@ void rcu_user_exit(void)
*/ */
static __always_inline void rcu_nmi_enter_common(bool irq) 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; long incby = 2;
/* Complain about underflow. */ /* 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 * If idle from RCU viewpoint, atomically increment ->dynticks
@ -836,10 +841,10 @@ static __always_inline void rcu_nmi_enter_common(bool irq)
incby = 1; incby = 1;
} }
trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="), trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
rdtp->dynticks_nmi_nesting, rdp->dynticks_nmi_nesting,
rdtp->dynticks_nmi_nesting + incby, rdtp->dynticks); rdp->dynticks_nmi_nesting + incby, rdtp->dynticks);
WRITE_ONCE(rdtp->dynticks_nmi_nesting, /* Prevent store tearing. */ WRITE_ONCE(rdp->dynticks_nmi_nesting, /* Prevent store tearing. */
rdtp->dynticks_nmi_nesting + incby); rdp->dynticks_nmi_nesting + incby);
barrier(); barrier();
} }
@ -3194,7 +3199,7 @@ rcu_boot_init_percpu_data(int cpu)
/* Set up local state, ensuring consistent view of global state. */ /* Set up local state, ensuring consistent view of global state. */
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu); rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
rdp->dynticks = &per_cpu(rcu_dynticks, 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))); 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_seq = rcu_state.gp_seq;
rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED; rdp->rcu_ofl_gp_flags = RCU_GP_CLEANED;
@ -3227,7 +3232,7 @@ int rcutree_prepare_cpu(unsigned int cpu)
if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */ if (rcu_segcblist_empty(&rdp->cblist) && /* No early-boot CBs? */
!init_nocb_callback_list(rdp)) !init_nocb_callback_list(rdp))
rcu_segcblist_init(&rdp->cblist); /* Re-enable callbacks. */ 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(); rcu_dynticks_eqs_online();
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */ raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled. */

2
kernel/rcu/tree.h
View File

@ -38,8 +38,6 @@
* Dynticks per-CPU state. * Dynticks per-CPU state.
*/ */
struct rcu_dynticks { 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. */ atomic_t dynticks; /* Even value for idle, else odd. */
}; };

2
kernel/rcu/tree_plugin.h
View File

@ -1831,7 +1831,7 @@ static void print_cpu_stall_info(int cpu)
"!."[!delta], "!."[!delta],
ticks_value, ticks_title, ticks_value, ticks_title,
rcu_dynticks_snap(rdtp) & 0xfff, 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), rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu),
READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, READ_ONCE(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart,
fast_no_hz); fast_no_hz);