rcu: Remove unused RCU list functions

Given changes to callback migration, rcu_cblist_head(),
rcu_cblist_tail(), rcu_cblist_count_cbs(), rcu_segcblist_segempty(),
rcu_segcblist_dequeued_lazy(), and rcu_segcblist_new_cbs() are
no longer used.  This commit therefore removes them.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/rcu_segcblist.c

@@ -35,24 +35,6 @@ void rcu_cblist_init(struct rcu_cblist *rclp)
 	rclp->len_lazy = 0;
 }
 
-/*
- * Debug function to actually count the number of callbacks.
- * If the number exceeds the limit specified, return -1.
- */
-long rcu_cblist_count_cbs(struct rcu_cblist *rclp, long lim)
-{
-	int cnt = 0;
-	struct rcu_head **rhpp = &rclp->head;
-
-	for (;;) {
-		if (!*rhpp)
-			return cnt;
-		if (++cnt > lim)
-			return -1;
-		rhpp = &(*rhpp)->next;
-	}
-}
-
 /*
  * Dequeue the oldest rcu_head structure from the specified callback
  * list.  This function assumes that the callback is non-lazy, but
@@ -102,17 +84,6 @@ void rcu_segcblist_disable(struct rcu_segcblist *rsclp)
 	rsclp->tails[RCU_NEXT_TAIL] = NULL;
 }
 
-/*
- * Is the specified segment of the specified rcu_segcblist structure
- * empty of callbacks?
- */
-bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg)
-{
-	if (seg == RCU_DONE_TAIL)
-		return &rsclp->head == rsclp->tails[RCU_DONE_TAIL];
-	return rsclp->tails[seg - 1] == rsclp->tails[seg];
-}
-
 /*
  * Does the specified rcu_segcblist structure contain callbacks that
  * are ready to be invoked?
@@ -133,50 +104,6 @@ bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp)
 	       !rcu_segcblist_restempty(rsclp, RCU_DONE_TAIL);
 }
 
-/*
- * Dequeue and return the first ready-to-invoke callback.  If there
- * are no ready-to-invoke callbacks, return NULL.  Disables interrupts
- * to avoid interference.  Does not protect from interference from other
- * CPUs or tasks.
- */
-struct rcu_head *rcu_segcblist_dequeue(struct rcu_segcblist *rsclp)
-{
-	unsigned long flags;
-	int i;
-	struct rcu_head *rhp;
-
-	local_irq_save(flags);
-	if (!rcu_segcblist_ready_cbs(rsclp)) {
-		local_irq_restore(flags);
-		return NULL;
-	}
-	rhp = rsclp->head;
-	BUG_ON(!rhp);
-	rsclp->head = rhp->next;
-	for (i = RCU_DONE_TAIL; i < RCU_CBLIST_NSEGS; i++) {
-		if (rsclp->tails[i] != &rhp->next)
-			break;
-		rsclp->tails[i] = &rsclp->head;
-	}
-	smp_mb(); /* Dequeue before decrement for rcu_barrier(). */
-	WRITE_ONCE(rsclp->len, rsclp->len - 1);
-	local_irq_restore(flags);
-	return rhp;
-}
-
-/*
- * Account for the fact that a previously dequeued callback turned out
- * to be marked as lazy.
- */
-void rcu_segcblist_dequeued_lazy(struct rcu_segcblist *rsclp)
-{
-	unsigned long flags;
-
-	local_irq_save(flags);
-	rsclp->len_lazy--;
-	local_irq_restore(flags);
-}
-
 /*
  * Return a pointer to the first callback in the specified rcu_segcblist
  * structure.  This is useful for diagnostics.
@@ -202,17 +129,6 @@ struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp)
 	return NULL;
 }
 
-/*
- * Does the specified rcu_segcblist structure contain callbacks that
- * have not yet been processed beyond having been posted, that is,
- * does it contain callbacks in its last segment?
- */
-bool rcu_segcblist_new_cbs(struct rcu_segcblist *rsclp)
-{
-	return rcu_segcblist_is_enabled(rsclp) &&
-	       !rcu_segcblist_restempty(rsclp, RCU_NEXT_READY_TAIL);
-}
-
 /*
  * Enqueue the specified callback onto the specified rcu_segcblist
  * structure, updating accounting as needed.  Note that the ->len

kernel/rcu/rcu_segcblist.h

@@ -31,29 +31,7 @@ static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp)
 	rclp->len_lazy--;
 }
 
-/*
- * Interim function to return rcu_cblist head pointer.  Longer term, the
- * rcu_cblist will be used more pervasively, removing the need for this
- * function.
- */
-static inline struct rcu_head *rcu_cblist_head(struct rcu_cblist *rclp)
-{
-	return rclp->head;
-}
-
-/*
- * Interim function to return rcu_cblist head pointer.  Longer term, the
- * rcu_cblist will be used more pervasively, removing the need for this
- * function.
- */
-static inline struct rcu_head **rcu_cblist_tail(struct rcu_cblist *rclp)
-{
-	WARN_ON_ONCE(!rclp->head);
-	return rclp->tail;
-}
-
 void rcu_cblist_init(struct rcu_cblist *rclp);
-long rcu_cblist_count_cbs(struct rcu_cblist *rclp, long lim);
 struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp);
 
 /*
@@ -134,14 +112,10 @@ static inline struct rcu_head **rcu_segcblist_tail(struct rcu_segcblist *rsclp)
 
 void rcu_segcblist_init(struct rcu_segcblist *rsclp);
 void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
-bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg);
 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
-struct rcu_head *rcu_segcblist_dequeue(struct rcu_segcblist *rsclp);
-void rcu_segcblist_dequeued_lazy(struct rcu_segcblist *rsclp);
 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
-bool rcu_segcblist_new_cbs(struct rcu_segcblist *rsclp);
 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
 			   struct rcu_head *rhp, bool lazy);
 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,