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. */
13 static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
14 {
15 return READ_ONCE(rclp->len);
16 }
17
18 long rcu_segcblist_get_seglen(struct rcu_segcblist *rsclp, int seg);
19
20 /* Return number of callbacks in segmented callback list by summing seglen. */
21 long rcu_segcblist_n_segment_cbs(struct rcu_segcblist *rsclp);
22
23 void rcu_cblist_init(struct rcu_cblist *rclp);
24 void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
25 void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
26 struct rcu_cblist *srclp,
27 struct rcu_head *rhp);
28 struct 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 */
43 static 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. */
49 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
50 {
51 #ifdef CONFIG_RCU_NOCB_CPU
52 return atomic_long_read(&rsclp->len);
53 #else
54 return READ_ONCE(rsclp->len);
55 #endif
56 }
57
58 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
59 int flags)
60 {
61 WRITE_ONCE(rsclp->flags, rsclp->flags | flags);
62 }
63
64 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
65 int flags)
66 {
67 WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags);
68 }
69
70 static 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 */
80 static 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 */
89 static 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_LOCKING))
93 return true;
94
95 return false;
96 }
97
98 static inline bool rcu_segcblist_completely_offloaded(struct rcu_segcblist *rsclp)
99 {
100 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
101 !rcu_segcblist_test_flags(rsclp, SEGCBLIST_RCU_CORE))
102 return true;
103
104 return false;
105 }
106
107 /*
108 * Are all segments following the specified segment of the specified
109 * rcu_segcblist structure empty of callbacks? (The specified
110 * segment might well contain callbacks.)
111 */
112 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
113 {
114 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
115 }
116
117 /*
118 * Is the specified segment of the specified rcu_segcblist structure
119 * empty of callbacks?
120 */
121 static inline bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg)
122 {
123 if (seg == RCU_DONE_TAIL)
124 return &rsclp->head == rsclp->tails[RCU_DONE_TAIL];
125 return rsclp->tails[seg - 1] == rsclp->tails[seg];
126 }
127
128 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
129 void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v);
130 void rcu_segcblist_init(struct rcu_segcblist *rsclp);
131 void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
132 void rcu_segcblist_offload(struct rcu_segcblist *rsclp, bool offload);
133 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
134 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
135 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
136 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
137 bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
138 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
139 struct rcu_head *rhp);
140 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
141 struct rcu_head *rhp);
142 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
143 struct rcu_cblist *rclp);
144 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
145 struct rcu_cblist *rclp);
146 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
147 struct rcu_cblist *rclp);
148 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
149 struct rcu_cblist *rclp);
150 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
151 struct rcu_cblist *rclp);
152 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
153 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
154 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
155 struct rcu_segcblist *src_rsclp);
156
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