1/* SPDX-License-Identifier: GPL-2.0+ */
  2/*
  3 * RCU segmented callback lists, internal-to-rcu header file
  4 *
  5 * Copyright IBM Corporation, 2017
  6 *
  7 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  8 */
  9
 10#include <linux/rcu_segcblist.h>
 11
 12/* Return number of callbacks in the specified callback list. */
 13static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
 14{
 15	return READ_ONCE(rclp->len);
 16}
 17
 18/*
 19 * Account for the fact that a previously dequeued callback turned out
 20 * to be marked as lazy.
 21 */
 22static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp)
 23{
 24	rclp->len_lazy--;
 25}
 26
 27void rcu_cblist_init(struct rcu_cblist *rclp);
 28void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
 29void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
 30			      struct rcu_cblist *srclp,
 31			      struct rcu_head *rhp);
 32struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp);
 33
 34/*
 35 * Is the specified rcu_segcblist structure empty?
 36 *
 37 * But careful!  The fact that the ->head field is NULL does not
 38 * necessarily imply that there are no callbacks associated with
 39 * this structure.  When callbacks are being invoked, they are
 40 * removed as a group.  If callback invocation must be preempted,
 41 * the remaining callbacks will be added back to the list.  Either
 42 * way, the counts are updated later.
 43 *
 44 * So it is often the case that rcu_segcblist_n_cbs() should be used
 45 * instead.
 46 */
 47static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp)
 48{
 49	return !READ_ONCE(rsclp->head);
 50}
 51
 52/* Return number of callbacks in segmented callback list. */
 53static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
 54{
 55#ifdef CONFIG_RCU_NOCB_CPU
 56	return atomic_long_read(&rsclp->len);
 57#else
 58	return READ_ONCE(rsclp->len);
 59#endif
 60}
 61
 62/* Return number of lazy callbacks in segmented callback list. */
 63static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp)
 64{
 65	return rsclp->len_lazy;
 66}
 67
 68/* Return number of lazy callbacks in segmented callback list. */
 69static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp)
 70{
 71	return rcu_segcblist_n_cbs(rsclp) - rsclp->len_lazy;
 72}
 73
 74/*
 75 * Is the specified rcu_segcblist enabled, for example, not corresponding
 76 * to an offline CPU?
 77 */
 78static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
 79{
 80	return rsclp->enabled;
 81}
 82
 83/* Is the specified rcu_segcblist offloaded?  */
 84static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
 85{
 86	return rsclp->offloaded;
 87}
 88
 89/*
 90 * Are all segments following the specified segment of the specified
 91 * rcu_segcblist structure empty of callbacks?  (The specified
 92 * segment might well contain callbacks.)
 93 */
 94static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
 95{
 96	return !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
 97}
 98
 99void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
100void rcu_segcblist_init(struct rcu_segcblist *rsclp);
101void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
102void rcu_segcblist_offload(struct rcu_segcblist *rsclp);
103bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
104bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
105struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
106struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
107bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
108void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
109			   struct rcu_head *rhp, bool lazy);
110bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
111			   struct rcu_head *rhp, bool lazy);
112void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp,
113				 struct rcu_cblist *rclp);
114void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
115				    struct rcu_cblist *rclp);
116void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
117				    struct rcu_cblist *rclp);
118void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
119				struct rcu_cblist *rclp);
120void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
121				   struct rcu_cblist *rclp);
122void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
123				   struct rcu_cblist *rclp);
124void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
125bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
126void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
127			 struct rcu_segcblist *src_rsclp);