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. */
rcu_cblist_n_cbs(struct rcu_cblist * rclp)13 static 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 */
rcu_cblist_dequeued_lazy(struct rcu_cblist * rclp)22 static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp)
23 {
24 rclp->len_lazy--;
25 }
26
27 void rcu_cblist_init(struct rcu_cblist *rclp);
28 void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
29 void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
30 struct rcu_cblist *srclp,
31 struct rcu_head *rhp);
32 struct 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 */
rcu_segcblist_empty(struct rcu_segcblist * rsclp)47 static 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. */
rcu_segcblist_n_cbs(struct rcu_segcblist * rsclp)53 static 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. */
rcu_segcblist_n_lazy_cbs(struct rcu_segcblist * rsclp)63 static 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. */
rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist * rsclp)69 static 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 */
rcu_segcblist_is_enabled(struct rcu_segcblist * rsclp)78 static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
79 {
80 return rsclp->enabled;
81 }
82
83 /* Is the specified rcu_segcblist offloaded? */
rcu_segcblist_is_offloaded(struct rcu_segcblist * rsclp)84 static 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 */
rcu_segcblist_restempty(struct rcu_segcblist * rsclp,int seg)94 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
95 {
96 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
97 }
98
99 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
100 void rcu_segcblist_init(struct rcu_segcblist *rsclp);
101 void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
102 void rcu_segcblist_offload(struct rcu_segcblist *rsclp);
103 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
104 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
105 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
106 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
107 bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
108 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
109 struct rcu_head *rhp, bool lazy);
110 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
111 struct rcu_head *rhp, bool lazy);
112 void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp,
113 struct rcu_cblist *rclp);
114 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
115 struct rcu_cblist *rclp);
116 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
117 struct rcu_cblist *rclp);
118 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
119 struct rcu_cblist *rclp);
120 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
121 struct rcu_cblist *rclp);
122 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
123 struct rcu_cblist *rclp);
124 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
125 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
126 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
127 struct rcu_segcblist *src_rsclp);
128