[PATCH 04/10] rcu: Implement rcu_segcblist_is_offloaded() config dependent

[Frederic Weisbecker]

This simplify the usage of this API and avoid checking the kernel
config from the callers.

Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
---
 include/linux/rcu_segcblist.h |  2 ++
 kernel/rcu/rcu_segcblist.c    |  2 ++
 kernel/rcu/rcu_segcblist.h    |  6 ++++++
 kernel/rcu/tree.c             | 21 +++++++--------------
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/include/linux/rcu_segcblist.h b/include/linux/rcu_segcblist.h
index b36afe7b22c9..0ced0a0ecbcf 100644
--- a/include/linux/rcu_segcblist.h
+++ b/include/linux/rcu_segcblist.h
@@ -73,7 +73,9 @@ struct rcu_segcblist {
 	long len;
 #endif
 	u8 enabled;
+#ifdef CONFIG_RCU_NOCB_CPU
 	u8 offloaded;
+#endif
 };
 
 #define RCU_SEGCBLIST_INITIALIZER(n) \
diff --git a/kernel/rcu/rcu_segcblist.c b/kernel/rcu/rcu_segcblist.c
index 9a0f66133b4b..d8ea2bef5574 100644
--- a/kernel/rcu/rcu_segcblist.c
+++ b/kernel/rcu/rcu_segcblist.c
@@ -166,6 +166,7 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
 	rsclp->enabled = 0;
 }
 
+#ifdef CONFIG_RCU_NOCB_CPU
 /*
  * Mark the specified rcu_segcblist structure as offloaded.  This
  * structure must be empty.
@@ -174,6 +175,7 @@ void rcu_segcblist_offload(struct rcu_segcblist *rsclp)
 {
 	rsclp->offloaded = 1;
 }
+#endif
 
 /*
  * Does the specified rcu_segcblist structure contain callbacks that
diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
index 5c293afc07b8..4c1503a82492 100644
--- a/kernel/rcu/rcu_segcblist.h
+++ b/kernel/rcu/rcu_segcblist.h
@@ -62,7 +62,11 @@ static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
 /* Is the specified rcu_segcblist offloaded?  */
 static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
 {
+#ifdef CONFIG_RCU_NOCB_CPU
 	return rsclp->offloaded;
+#else
+	return false;
+#endif
 }
 
 /*
@@ -78,7 +82,9 @@ static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
 void rcu_segcblist_init(struct rcu_segcblist *rsclp);
 void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
+#ifdef CONFIG_RCU_NOCB_CPU
 void rcu_segcblist_offload(struct rcu_segcblist *rsclp);
+#endif
 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d9a49cd6065a..804cf7dfff03 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1401,8 +1401,7 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp)
 {
 	bool ret = false;
 	bool need_qs;
-	const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
-			       rcu_segcblist_is_offloaded(&rdp->cblist);
+	const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
 
 	raw_lockdep_assert_held_rcu_node(rnp);
 
@@ -1790,8 +1789,7 @@ static void rcu_gp_cleanup(void)
 		needgp = true;
 	}
 	/* Advance CBs to reduce false positives below. */
-	offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
-		    rcu_segcblist_is_offloaded(&rdp->cblist);
+	offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
 	if ((offloaded || !rcu_accelerate_cbs(rnp, rdp)) && needgp) {
 		WRITE_ONCE(rcu_state.gp_flags, RCU_GP_FLAG_INIT);
 		WRITE_ONCE(rcu_state.gp_req_activity, jiffies);
@@ -1985,8 +1983,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp)
 	unsigned long flags;
 	unsigned long mask;
 	bool needwake = false;
-	const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
-			       rcu_segcblist_is_offloaded(&rdp->cblist);
+	const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
 	struct rcu_node *rnp;
 
 	rnp = rdp->mynode;
@@ -2153,8 +2150,7 @@ int rcutree_dead_cpu(unsigned int cpu)
 static void rcu_do_batch(struct rcu_data *rdp)
 {
 	unsigned long flags;
-	const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
-			       rcu_segcblist_is_offloaded(&rdp->cblist);
+	const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
 	struct rcu_head *rhp;
 	struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
 	long bl, count;
@@ -2397,8 +2393,7 @@ static __latent_entropy void rcu_core(void)
 	unsigned long flags;
 	struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);
 	struct rcu_node *rnp = rdp->mynode;
-	const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
-			       rcu_segcblist_is_offloaded(&rdp->cblist);
+	const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
 
 	if (cpu_is_offline(smp_processor_id()))
 		return;
@@ -2695,8 +2690,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
 				   rcu_segcblist_n_cbs(&rdp->cblist));
 
 	/* Go handle any RCU core processing required. */
-	if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
-	    unlikely(rcu_segcblist_is_offloaded(&rdp->cblist))) {
+	if (unlikely(rcu_segcblist_is_offloaded(&rdp->cblist))) {
 		__call_rcu_nocb_wake(rdp, was_alldone, flags); /* unlocks */
 	} else {
 		__call_rcu_core(rdp, head, flags);
@@ -3243,8 +3237,7 @@ static int rcu_pending(int user)
 
 	/* Has RCU gone idle with this CPU needing another grace period? */
 	if (!gp_in_progress && rcu_segcblist_is_enabled(&rdp->cblist) &&
-	    (!IS_ENABLED(CONFIG_RCU_NOCB_CPU) ||
-	     !rcu_segcblist_is_offloaded(&rdp->cblist)) &&
+	    !rcu_segcblist_is_offloaded(&rdp->cblist) &&
 	    !rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL))
 		return 1;
 
-- 
2.25.0