rcu: Remove rcu_state structure's ->rda field

The rcu_state structure's ->rda field was used to find the per-CPU
rcu_data structures corresponding to that rcu_state structure.  But now
there is only one rcu_state structure (creatively named "rcu_state")
and one set of per-CPU rcu_data structures (creatively named "rcu_data").
Therefore, uses of the ->rda field can always be replaced by "rcu_data,
and this commit makes that change and removes the ->rda field.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/tree.h

@@ -312,7 +312,6 @@ struct rcu_state {
 	struct rcu_node *level[RCU_NUM_LVLS + 1];
 						/* Hierarchy levels (+1 to */
 						/*  shut bogus gcc warning) */
-	struct rcu_data __percpu *rda;		/* pointer of percu rcu_data. */
 	int ncpus;				/* # CPUs seen so far. */
 
 	/* The following fields are guarded by the root rcu_node's lock. */

kernel/rcu/tree_exp.h

@@ -286,7 +286,7 @@ static bool sync_exp_work_done(struct rcu_state *rsp, unsigned long s)
  */
 static bool exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
 {
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
+	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id());
 	struct rcu_node *rnp = rdp->mynode;
 	struct rcu_node *rnp_root = rcu_get_root(rsp);
 
@@ -361,7 +361,7 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
 	mask_ofl_test = 0;
 	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(rsp->rda, cpu);
+		struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 		struct rcu_dynticks *rdtp = per_cpu_ptr(&rcu_dynticks, cpu);
 		int snap;
 
@@ -390,7 +390,7 @@ static void sync_rcu_exp_select_node_cpus(struct work_struct *wp)
 	/* IPI the remaining CPUs for expedited quiescent state. */
 	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(rsp->rda, cpu);
+		struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 
 		if (!(mask_ofl_ipi & mask))
 			continue;
@@ -509,7 +509,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
 				if (!(rnp->expmask & mask))
 					continue;
 				ndetected++;
-				rdp = per_cpu_ptr(rsp->rda, cpu);
+				rdp = per_cpu_ptr(&rcu_data, cpu);
 				pr_cont(" %d-%c%c%c", cpu,
 					"O."[!!cpu_online(cpu)],
 					"o."[!!(rdp->grpmask & rnp->expmaskinit)],
@@ -642,7 +642,7 @@ static void _synchronize_rcu_expedited(struct rcu_state *rsp,
 	}
 
 	/* Wait for expedited grace period to complete. */
-	rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
+	rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id());
 	rnp = rcu_get_root(rsp);
 	wait_event(rnp->exp_wq[rcu_seq_ctr(s) & 0x3],
 		   sync_exp_work_done(rsp, s));
@@ -665,7 +665,7 @@ static void sync_rcu_exp_handler(void *info)
 {
 	unsigned long flags;
 	struct rcu_state *rsp = info;
-	struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
+	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 	struct rcu_node *rnp = rdp->mynode;
 	struct task_struct *t = current;
 
@@ -772,13 +772,12 @@ EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
 #else /* #ifdef CONFIG_PREEMPT_RCU */
 
 /* Invoked on each online non-idle CPU for expedited quiescent state. */
-static void sync_sched_exp_handler(void *data)
+static void sync_sched_exp_handler(void *unused)
 {
 	struct rcu_data *rdp;
 	struct rcu_node *rnp;
-	struct rcu_state *rsp = data;
 
-	rdp = this_cpu_ptr(rsp->rda);
+	rdp = this_cpu_ptr(&rcu_data);
 	rnp = rdp->mynode;
 	if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
 	    __this_cpu_read(rcu_data.cpu_no_qs.b.exp))
@@ -801,7 +800,7 @@ static void sync_sched_exp_online_cleanup(int cpu)
 	struct rcu_node *rnp;
 	struct rcu_state *rsp = &rcu_state;
 
-	rdp = per_cpu_ptr(rsp->rda, cpu);
+	rdp = per_cpu_ptr(&rcu_data, cpu);
 	rnp = rdp->mynode;
 	if (!(READ_ONCE(rnp->expmask) & rdp->grpmask))
 		return;

kernel/rcu/tree_plugin.h

@@ -328,7 +328,7 @@ static void rcu_qs(void)
 void rcu_note_context_switch(bool preempt)
 {
 	struct task_struct *t = current;
-	struct rcu_data *rdp = this_cpu_ptr(rcu_state_p->rda);
+	struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
 	struct rcu_node *rnp;
 
 	barrier(); /* Avoid RCU read-side critical sections leaking down. */
@@ -488,7 +488,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
 	 * t->rcu_read_unlock_special cannot change.
 	 */
 	special = t->rcu_read_unlock_special;
-	rdp = this_cpu_ptr(rcu_state_p->rda);
+	rdp = this_cpu_ptr(&rcu_data);
 	if (!special.s && !rdp->deferred_qs) {
 		local_irq_restore(flags);
 		return;
@@ -911,7 +911,7 @@ dump_blkd_tasks(struct rcu_state *rsp, struct rcu_node *rnp, int ncheck)
 	}
 	pr_cont("\n");
 	for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) {
-		rdp = per_cpu_ptr(rsp->rda, cpu);
+		rdp = per_cpu_ptr(&rcu_data, cpu);
 		onl = !!(rdp->grpmask & rcu_rnp_online_cpus(rnp));
 		pr_info("\t%d: %c online: %ld(%d) offline: %ld(%d)\n",
 			cpu, ".o"[onl],
@@ -1437,7 +1437,7 @@ static void __init rcu_spawn_boost_kthreads(void)
 
 static void rcu_prepare_kthreads(int cpu)
 {
-	struct rcu_data *rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
+	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	struct rcu_node *rnp = rdp->mynode;
 
 	/* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
@@ -1574,7 +1574,7 @@ static bool __maybe_unused rcu_try_advance_all_cbs(void)
 	rdtp->last_advance_all = jiffies;
 
 	for_each_rcu_flavor(rsp) {
-		rdp = this_cpu_ptr(rsp->rda);
+		rdp = this_cpu_ptr(&rcu_data);
 		rnp = rdp->mynode;
 
 		/*
@@ -1692,7 +1692,7 @@ static void rcu_prepare_for_idle(void)
 		return;
 	rdtp->last_accelerate = jiffies;
 	for_each_rcu_flavor(rsp) {
-		rdp = this_cpu_ptr(rsp->rda);
+		rdp = this_cpu_ptr(&rcu_data);
 		if (!rcu_segcblist_pend_cbs(&rdp->cblist))
 			continue;
 		rnp = rdp->mynode;
@@ -1778,7 +1778,7 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
 {
 	unsigned long delta;
 	char fast_no_hz[72];
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	struct rcu_dynticks *rdtp = rdp->dynticks;
 	char *ticks_title;
 	unsigned long ticks_value;
@@ -1833,7 +1833,7 @@ static void increment_cpu_stall_ticks(void)
 	struct rcu_state *rsp;
 
 	for_each_rcu_flavor(rsp)
-		raw_cpu_inc(rsp->rda->ticks_this_gp);
+		raw_cpu_inc(rcu_data.ticks_this_gp);
 }
 
 #ifdef CONFIG_RCU_NOCB_CPU
@@ -1965,7 +1965,7 @@ static void wake_nocb_leader_defer(struct rcu_data *rdp, int waketype,
  */
 static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu)
 {
-	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
+	struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
 	unsigned long ret;
 #ifdef CONFIG_PROVE_RCU
 	struct rcu_head *rhp;
@@ -2426,7 +2426,7 @@ void __init rcu_init_nohz(void)
 
 	for_each_rcu_flavor(rsp) {
 		for_each_cpu(cpu, rcu_nocb_mask)
-			init_nocb_callback_list(per_cpu_ptr(rsp->rda, cpu));
+			init_nocb_callback_list(per_cpu_ptr(&rcu_data, cpu));
 		rcu_organize_nocb_kthreads(rsp);
 	}
 }
@@ -2452,7 +2452,7 @@ static void rcu_spawn_one_nocb_kthread(struct rcu_state *rsp, int cpu)
 	struct rcu_data *rdp;
 	struct rcu_data *rdp_last;
 	struct rcu_data *rdp_old_leader;
-	struct rcu_data *rdp_spawn = per_cpu_ptr(rsp->rda, cpu);
+	struct rcu_data *rdp_spawn = per_cpu_ptr(&rcu_data, cpu);
 	struct task_struct *t;
 
 	/*
@@ -2545,7 +2545,7 @@ static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp)
 	 * we will spawn the needed set of rcu_nocb_kthread() kthreads.
 	 */
 	for_each_cpu(cpu, rcu_nocb_mask) {
-		rdp = per_cpu_ptr(rsp->rda, cpu);
+		rdp = per_cpu_ptr(&rcu_data, cpu);
 		if (rdp->cpu >= nl) {
 			/* New leader, set up for followers & next leader. */
 			nl = DIV_ROUND_UP(rdp->cpu + 1, ls) * ls;