From 4c5273bf2b5ed9b585e470dda19c09c875a9fbbd Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 3 Aug 2018 21:00:38 -0700 Subject: [PATCH] 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 --- 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 7ec0ba885273..bfa264a6f3fc 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(); } @@ -634,7 +635,7 @@ void rcu_user_enter(void) /* * If we are returning from the outermost NMI handler that interrupted an - * RCU-idle period, update rdtp->dynticks and 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. * @@ -643,30 +644,31 @@ 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(); @@ -739,25 +741,27 @@ 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); } /** @@ -799,7 +803,7 @@ 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.) @@ -809,11 +813,12 @@ 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 @@ -836,10 +841,10 @@ 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(); } @@ -3194,7 +3199,7 @@ 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; @@ -3227,7 +3232,7 @@ 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);