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
18long rcu_segcblist_get_seglen(struct rcu_segcblist *rsclp, int seg);
19
20/* Return number of callbacks in segmented callback list by summing seglen. */
21long rcu_segcblist_n_segment_cbs(struct rcu_segcblist *rsclp);
22
23void rcu_cblist_init(struct rcu_cblist *rclp);
24void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
25void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
26 struct rcu_cblist *srclp,
27 struct rcu_head *rhp);
28struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp);
29
30/*
31 * Is the specified rcu_segcblist structure empty?
32 *
33 * But careful! The fact that the ->head field is NULL does not
34 * necessarily imply that there are no callbacks associated with
35 * this structure. When callbacks are being invoked, they are
36 * removed as a group. If callback invocation must be preempted,
37 * the remaining callbacks will be added back to the list. Either
38 * way, the counts are updated later.
39 *
40 * So it is often the case that rcu_segcblist_n_cbs() should be used
41 * instead.
42 */
43static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp)
44{
45 return !READ_ONCE(rsclp->head);
46}
47
48/* Return number of callbacks in segmented callback list. */
49static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
50{
51#ifdef CONFIG_RCU_NOCB_CPU
52 return atomic_long_read(v: &rsclp->len);
53#else
54 return READ_ONCE(rsclp->len);
55#endif
56}
57
58static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
59 int flags)
60{
61 WRITE_ONCE(rsclp->flags, rsclp->flags | flags);
62}
63
64static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
65 int flags)
66{
67 WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags);
68}
69
70static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
71 int flags)
72{
73 return READ_ONCE(rsclp->flags) & flags;
74}
75
76/*
77 * Is the specified rcu_segcblist enabled, for example, not corresponding
78 * to an offline CPU?
79 */
80static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
81{
82 return rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED);
83}
84
85/*
86 * Is the specified rcu_segcblist NOCB offloaded (or in the middle of the
87 * [de]offloading process)?
88 */
89static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
90{
91 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
92 rcu_segcblist_test_flags(rsclp, SEGCBLIST_OFFLOADED))
93 return true;
94
95 return false;
96}
97
98/*
99 * Are all segments following the specified segment of the specified
100 * rcu_segcblist structure empty of callbacks? (The specified
101 * segment might well contain callbacks.)
102 */
103static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
104{
105 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
106}
107
108/*
109 * Is the specified segment of the specified rcu_segcblist structure
110 * empty of callbacks?
111 */
112static inline bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg)
113{
114 if (seg == RCU_DONE_TAIL)
115 return &rsclp->head == rsclp->tails[RCU_DONE_TAIL];
116 return rsclp->tails[seg - 1] == rsclp->tails[seg];
117}
118
119void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
120void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v);
121void rcu_segcblist_init(struct rcu_segcblist *rsclp);
122void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
123bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
124bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
125struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
126struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
127bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
128void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
129 struct rcu_head *rhp);
130bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
131 struct rcu_head *rhp);
132void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
133 struct rcu_cblist *rclp);
134void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
135 struct rcu_cblist *rclp);
136void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
137 struct rcu_cblist *rclp);
138void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
139 struct rcu_cblist *rclp);
140void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
141 struct rcu_cblist *rclp);
142void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
143bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
144void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
145 struct rcu_segcblist *src_rsclp);
146

source code of linux/kernel/rcu/rcu_segcblist.h