From b97d23c51c9fee56b0c7598c323ab2846d873f2d Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 4 Jul 2018 15:35:00 -0700 Subject: [PATCH] rcu: Remove for_each_rcu_flavor() flavor-traversal macro Now that there is only ever a single flavor of RCU in a given kernel build, there isn't a whole lot of point in having a flavor-traversal macro. This commit therefore removes it and converts calls to it to straightline code, inlining trivial functions as appropriate. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 172 ++++++++++++++++----------------------- kernel/rcu/tree.h | 7 -- kernel/rcu/tree_plugin.h | 57 +++++-------- 3 files changed, 91 insertions(+), 145 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index aeff9024bb6c..46a32999020d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -85,8 +85,6 @@ struct rcu_state rcu_state = { .ofl_lock = __SPIN_LOCK_UNLOCKED(rcu_state.ofl_lock), }; -LIST_HEAD(rcu_struct_flavors); - /* Dump rcu_node combining tree at boot to verify correct setup. */ static bool dump_tree; module_param(dump_tree, bool, 0444); @@ -568,31 +566,28 @@ void show_rcu_gp_kthreads(void) int cpu; struct rcu_data *rdp; struct rcu_node *rnp; - struct rcu_state *rsp; - for_each_rcu_flavor(rsp) { - pr_info("%s: wait state: %d ->state: %#lx\n", - rsp->name, rsp->gp_state, rsp->gp_kthread->state); - rcu_for_each_node_breadth_first(rnp) { - if (ULONG_CMP_GE(rsp->gp_seq, rnp->gp_seq_needed)) + pr_info("%s: wait state: %d ->state: %#lx\n", rcu_state.name, + rcu_state.gp_state, rcu_state.gp_kthread->state); + rcu_for_each_node_breadth_first(rnp) { + if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed)) + continue; + pr_info("\trcu_node %d:%d ->gp_seq %lu ->gp_seq_needed %lu\n", + rnp->grplo, rnp->grphi, rnp->gp_seq, + rnp->gp_seq_needed); + if (!rcu_is_leaf_node(rnp)) + continue; + for_each_leaf_node_possible_cpu(rnp, cpu) { + rdp = per_cpu_ptr(&rcu_data, cpu); + if (rdp->gpwrap || + ULONG_CMP_GE(rcu_state.gp_seq, + rdp->gp_seq_needed)) continue; - pr_info("\trcu_node %d:%d ->gp_seq %lu ->gp_seq_needed %lu\n", - rnp->grplo, rnp->grphi, rnp->gp_seq, - rnp->gp_seq_needed); - if (!rcu_is_leaf_node(rnp)) - continue; - for_each_leaf_node_possible_cpu(rnp, cpu) { - rdp = per_cpu_ptr(&rcu_data, cpu); - if (rdp->gpwrap || - ULONG_CMP_GE(rsp->gp_seq, - rdp->gp_seq_needed)) - continue; - pr_info("\tcpu %d ->gp_seq_needed %lu\n", - cpu, rdp->gp_seq_needed); - } + pr_info("\tcpu %d ->gp_seq_needed %lu\n", + cpu, rdp->gp_seq_needed); } - /* sched_show_task(rsp->gp_kthread); */ } + /* sched_show_task(rcu_state.gp_kthread); */ } EXPORT_SYMBOL_GPL(show_rcu_gp_kthreads); @@ -638,7 +633,6 @@ static struct rcu_node *rcu_get_root(void) */ static void rcu_eqs_enter(bool user) { - struct rcu_state *rsp; struct rcu_data *rdp; struct rcu_dynticks *rdtp; @@ -655,10 +649,8 @@ static void rcu_eqs_enter(bool user) lockdep_assert_irqs_disabled(); trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0, rdtp->dynticks); WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current)); - for_each_rcu_flavor(rsp) { - rdp = this_cpu_ptr(&rcu_data); - do_nocb_deferred_wakeup(rdp); - } + 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. */ @@ -1024,21 +1016,17 @@ bool rcu_lockdep_current_cpu_online(void) { struct rcu_data *rdp; struct rcu_node *rnp; - struct rcu_state *rsp; + bool ret = false; if (in_nmi() || !rcu_scheduler_fully_active) return true; preempt_disable(); - for_each_rcu_flavor(rsp) { - rdp = this_cpu_ptr(&rcu_data); - rnp = rdp->mynode; - if (rdp->grpmask & rcu_rnp_online_cpus(rnp)) { - preempt_enable(); - return true; - } - } + rdp = this_cpu_ptr(&rcu_data); + rnp = rdp->mynode; + if (rdp->grpmask & rcu_rnp_online_cpus(rnp)) + ret = true; preempt_enable(); - return false; + return ret; } EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); @@ -1516,10 +1504,7 @@ static void check_cpu_stall(struct rcu_data *rdp) */ void rcu_cpu_stall_reset(void) { - struct rcu_state *rsp; - - for_each_rcu_flavor(rsp) - WRITE_ONCE(rsp->jiffies_stall, jiffies + ULONG_MAX / 2); + WRITE_ONCE(rcu_state.jiffies_stall, jiffies + ULONG_MAX / 2); } /* Trace-event wrapper function for trace_rcu_future_grace_period. */ @@ -3134,17 +3119,12 @@ static bool rcu_cpu_has_callbacks(bool *all_lazy) bool al = true; bool hc = false; struct rcu_data *rdp; - struct rcu_state *rsp; - for_each_rcu_flavor(rsp) { - rdp = this_cpu_ptr(&rcu_data); - if (rcu_segcblist_empty(&rdp->cblist)) - continue; + rdp = this_cpu_ptr(&rcu_data); + if (!rcu_segcblist_empty(&rdp->cblist)) { hc = true; - if (rcu_segcblist_n_nonlazy_cbs(&rdp->cblist) || !all_lazy) { + if (rcu_segcblist_n_nonlazy_cbs(&rdp->cblist)) al = false; - break; - } } if (all_lazy) *all_lazy = al; @@ -3436,15 +3416,12 @@ int rcutree_online_cpu(unsigned int cpu) unsigned long flags; struct rcu_data *rdp; struct rcu_node *rnp; - struct rcu_state *rsp; - for_each_rcu_flavor(rsp) { - rdp = per_cpu_ptr(&rcu_data, cpu); - rnp = rdp->mynode; - raw_spin_lock_irqsave_rcu_node(rnp, flags); - rnp->ffmask |= rdp->grpmask; - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - } + rdp = per_cpu_ptr(&rcu_data, cpu); + rnp = rdp->mynode; + raw_spin_lock_irqsave_rcu_node(rnp, flags); + rnp->ffmask |= rdp->grpmask; + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); if (IS_ENABLED(CONFIG_TREE_SRCU)) srcu_online_cpu(cpu); if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE) @@ -3463,15 +3440,12 @@ int rcutree_offline_cpu(unsigned int cpu) unsigned long flags; struct rcu_data *rdp; struct rcu_node *rnp; - struct rcu_state *rsp; - for_each_rcu_flavor(rsp) { - rdp = per_cpu_ptr(&rcu_data, cpu); - rnp = rdp->mynode; - raw_spin_lock_irqsave_rcu_node(rnp, flags); - rnp->ffmask &= ~rdp->grpmask; - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - } + rdp = per_cpu_ptr(&rcu_data, cpu); + rnp = rdp->mynode; + raw_spin_lock_irqsave_rcu_node(rnp, flags); + rnp->ffmask &= ~rdp->grpmask; + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); rcutree_affinity_setting(cpu, cpu); if (IS_ENABLED(CONFIG_TREE_SRCU)) @@ -3500,34 +3474,32 @@ void rcu_cpu_starting(unsigned int cpu) unsigned long oldmask; struct rcu_data *rdp; struct rcu_node *rnp; - struct rcu_state *rsp; + struct rcu_state *rsp = &rcu_state; if (per_cpu(rcu_cpu_started, cpu)) return; per_cpu(rcu_cpu_started, cpu) = 1; - for_each_rcu_flavor(rsp) { - rdp = per_cpu_ptr(&rcu_data, cpu); - rnp = rdp->mynode; - mask = rdp->grpmask; - raw_spin_lock_irqsave_rcu_node(rnp, flags); - rnp->qsmaskinitnext |= mask; - oldmask = rnp->expmaskinitnext; - rnp->expmaskinitnext |= mask; - oldmask ^= rnp->expmaskinitnext; - nbits = bitmap_weight(&oldmask, BITS_PER_LONG); - /* Allow lockless access for expedited grace periods. */ - smp_store_release(&rsp->ncpus, rsp->ncpus + nbits); /* ^^^ */ - rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */ - rdp->rcu_onl_gp_seq = READ_ONCE(rsp->gp_seq); - rdp->rcu_onl_gp_flags = READ_ONCE(rsp->gp_flags); - if (rnp->qsmask & mask) { /* RCU waiting on incoming CPU? */ - /* Report QS -after- changing ->qsmaskinitnext! */ - rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags); - } else { - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - } + rdp = per_cpu_ptr(&rcu_data, cpu); + rnp = rdp->mynode; + mask = rdp->grpmask; + raw_spin_lock_irqsave_rcu_node(rnp, flags); + rnp->qsmaskinitnext |= mask; + oldmask = rnp->expmaskinitnext; + rnp->expmaskinitnext |= mask; + oldmask ^= rnp->expmaskinitnext; + nbits = bitmap_weight(&oldmask, BITS_PER_LONG); + /* Allow lockless access for expedited grace periods. */ + smp_store_release(&rsp->ncpus, rsp->ncpus + nbits); /* ^^^ */ + rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */ + rdp->rcu_onl_gp_seq = READ_ONCE(rsp->gp_seq); + rdp->rcu_onl_gp_flags = READ_ONCE(rsp->gp_flags); + if (rnp->qsmask & mask) { /* RCU waiting on incoming CPU? */ + /* Report QS -after- changing ->qsmaskinitnext! */ + rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags); + } else { + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } smp_mb(); /* Ensure RCU read-side usage follows above initialization. */ } @@ -3644,7 +3616,6 @@ static int __init rcu_spawn_gp_kthread(void) unsigned long flags; int kthread_prio_in = kthread_prio; struct rcu_node *rnp; - struct rcu_state *rsp; struct sched_param sp; struct task_struct *t; @@ -3664,19 +3635,17 @@ static int __init rcu_spawn_gp_kthread(void) kthread_prio, kthread_prio_in); rcu_scheduler_fully_active = 1; - for_each_rcu_flavor(rsp) { - t = kthread_create(rcu_gp_kthread, NULL, "%s", rsp->name); - BUG_ON(IS_ERR(t)); - rnp = rcu_get_root(); - raw_spin_lock_irqsave_rcu_node(rnp, flags); - rsp->gp_kthread = t; - if (kthread_prio) { - sp.sched_priority = kthread_prio; - sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); - } - raw_spin_unlock_irqrestore_rcu_node(rnp, flags); - wake_up_process(t); + t = kthread_create(rcu_gp_kthread, NULL, "%s", rcu_state.name); + BUG_ON(IS_ERR(t)); + rnp = rcu_get_root(); + raw_spin_lock_irqsave_rcu_node(rnp, flags); + rcu_state.gp_kthread = t; + if (kthread_prio) { + sp.sched_priority = kthread_prio; + sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); } + raw_spin_unlock_irqrestore_rcu_node(rnp, flags); + wake_up_process(t); rcu_spawn_nocb_kthreads(); rcu_spawn_boost_kthreads(); return 0; @@ -3782,7 +3751,6 @@ static void __init rcu_init_one(void) per_cpu_ptr(&rcu_data, i)->mynode = rnp; rcu_boot_init_percpu_data(i); } - list_add(&rsp->flavors, &rcu_struct_flavors); } /* diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 6f1b1a3fc23d..8abc15c42d84 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -360,7 +360,6 @@ struct rcu_state { /* jiffies. */ const char *name; /* Name of structure. */ char abbr; /* Abbreviated name. */ - struct list_head flavors; /* List of RCU flavors. */ spinlock_t ofl_lock ____cacheline_internodealigned_in_smp; /* Synchronize offline with */ @@ -417,12 +416,6 @@ static const char *tp_rcu_varname __used __tracepoint_string = rcu_name; #define RCU_NAME rcu_name #endif /* #else #ifdef CONFIG_TRACING */ -extern struct list_head rcu_struct_flavors; - -/* Sequence through rcu_state structures for each RCU flavor. */ -#define for_each_rcu_flavor(rsp) \ - list_for_each_entry((rsp), &rcu_struct_flavors, flavors) - /* * RCU implementation internal declarations: */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 59d66ee26310..878a1d2cd465 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -1561,31 +1561,28 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void) struct rcu_data *rdp; struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks); struct rcu_node *rnp; - struct rcu_state *rsp; /* Exit early if we advanced recently. */ if (jiffies == rdtp->last_advance_all) return false; rdtp->last_advance_all = jiffies; - for_each_rcu_flavor(rsp) { - rdp = this_cpu_ptr(&rcu_data); - rnp = rdp->mynode; + rdp = this_cpu_ptr(&rcu_data); + rnp = rdp->mynode; - /* - * Don't bother checking unless a grace period has - * completed since we last checked and there are - * callbacks not yet ready to invoke. - */ - if ((rcu_seq_completed_gp(rdp->gp_seq, - rcu_seq_current(&rnp->gp_seq)) || - unlikely(READ_ONCE(rdp->gpwrap))) && - rcu_segcblist_pend_cbs(&rdp->cblist)) - note_gp_changes(rdp); + /* + * Don't bother checking unless a grace period has + * completed since we last checked and there are + * callbacks not yet ready to invoke. + */ + if ((rcu_seq_completed_gp(rdp->gp_seq, + rcu_seq_current(&rnp->gp_seq)) || + unlikely(READ_ONCE(rdp->gpwrap))) && + rcu_segcblist_pend_cbs(&rdp->cblist)) + note_gp_changes(rdp); - if (rcu_segcblist_ready_cbs(&rdp->cblist)) - cbs_ready = true; - } + if (rcu_segcblist_ready_cbs(&rdp->cblist)) + cbs_ready = true; return cbs_ready; } @@ -1648,7 +1645,6 @@ static void rcu_prepare_for_idle(void) struct rcu_data *rdp; struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks); struct rcu_node *rnp; - struct rcu_state *rsp; int tne; lockdep_assert_irqs_disabled(); @@ -1686,10 +1682,8 @@ static void rcu_prepare_for_idle(void) if (rdtp->last_accelerate == jiffies) return; rdtp->last_accelerate = jiffies; - for_each_rcu_flavor(rsp) { - rdp = this_cpu_ptr(&rcu_data); - if (!rcu_segcblist_pend_cbs(&rdp->cblist)) - continue; + rdp = this_cpu_ptr(&rcu_data); + if (rcu_segcblist_pend_cbs(&rdp->cblist)) { rnp = rdp->mynode; raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */ needwake = rcu_accelerate_cbs(rnp, rdp); @@ -1824,10 +1818,7 @@ static void zero_cpu_stall_ticks(struct rcu_data *rdp) /* Increment ->ticks_this_gp for all flavors of RCU. */ static void increment_cpu_stall_ticks(void) { - struct rcu_state *rsp; - - for_each_rcu_flavor(rsp) - raw_cpu_inc(rcu_data.ticks_this_gp); + raw_cpu_inc(rcu_data.ticks_this_gp); } #ifdef CONFIG_RCU_NOCB_CPU @@ -2384,7 +2375,6 @@ void __init rcu_init_nohz(void) { int cpu; bool need_rcu_nocb_mask = false; - struct rcu_state *rsp; #if defined(CONFIG_NO_HZ_FULL) if (tick_nohz_full_running && cpumask_weight(tick_nohz_full_mask)) @@ -2418,11 +2408,9 @@ void __init rcu_init_nohz(void) if (rcu_nocb_poll) pr_info("\tPoll for callbacks from no-CBs CPUs.\n"); - for_each_rcu_flavor(rsp) { - for_each_cpu(cpu, rcu_nocb_mask) - init_nocb_callback_list(per_cpu_ptr(&rcu_data, cpu)); - rcu_organize_nocb_kthreads(); - } + for_each_cpu(cpu, rcu_nocb_mask) + init_nocb_callback_list(per_cpu_ptr(&rcu_data, cpu)); + rcu_organize_nocb_kthreads(); } /* Initialize per-rcu_data variables for no-CBs CPUs. */ @@ -2489,11 +2477,8 @@ static void rcu_spawn_one_nocb_kthread(int cpu) */ static void rcu_spawn_all_nocb_kthreads(int cpu) { - struct rcu_state *rsp; - if (rcu_scheduler_fully_active) - for_each_rcu_flavor(rsp) - rcu_spawn_one_nocb_kthread(cpu); + rcu_spawn_one_nocb_kthread(cpu); } /*