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 <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index aeff902..46a3299 100644 (file)
--- 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))
-                               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))
+       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;
-                       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 6f1b1a3..8abc15c 100644 (file)
--- 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 59d66ee..878a1d2 100644 (file)
--- 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);
-
-               if (rcu_segcblist_ready_cbs(&rdp->cblist))
-                       cbs_ready = true;
-       }
+       /*
+        * 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;
        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);
 }
 
 /*