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 /* Return number of callbacks in segmented callback list by summing seglen. */
19 long rcu_segcblist_n_segment_cbs(struct rcu_segcblist *rsclp);
20
21 void rcu_cblist_init(struct rcu_cblist *rclp);
22 void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp);
23 void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp,
24 struct rcu_cblist *srclp,
25 struct rcu_head *rhp);
26 struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp);
27
28 /*
29 * Is the specified rcu_segcblist structure empty?
30 *
31 * But careful! The fact that the ->head field is NULL does not
32 * necessarily imply that there are no callbacks associated with
33 * this structure. When callbacks are being invoked, they are
34 * removed as a group. If callback invocation must be preempted,
35 * the remaining callbacks will be added back to the list. Either
36 * way, the counts are updated later.
37 *
38 * So it is often the case that rcu_segcblist_n_cbs() should be used
39 * instead.
40 */
rcu_segcblist_empty(struct rcu_segcblist * rsclp)41 static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp)
42 {
43 return !READ_ONCE(rsclp->head);
44 }
45
46 /* Return number of callbacks in segmented callback list. */
rcu_segcblist_n_cbs(struct rcu_segcblist * rsclp)47 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
48 {
49 #ifdef CONFIG_RCU_NOCB_CPU
50 return atomic_long_read(&rsclp->len);
51 #else
52 return READ_ONCE(rsclp->len);
53 #endif
54 }
55
rcu_segcblist_set_flags(struct rcu_segcblist * rsclp,int flags)56 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
57 int flags)
58 {
59 WRITE_ONCE(rsclp->flags, rsclp->flags | flags);
60 }
61
rcu_segcblist_clear_flags(struct rcu_segcblist * rsclp,int flags)62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
63 int flags)
64 {
65 WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags);
66 }
67
rcu_segcblist_test_flags(struct rcu_segcblist * rsclp,int flags)68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
69 int flags)
70 {
71 return READ_ONCE(rsclp->flags) & flags;
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 rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED);
81 }
82
83 /*
84 * Is the specified rcu_segcblist NOCB offloaded (or in the middle of the
85 * [de]offloading process)?
86 */
rcu_segcblist_is_offloaded(struct rcu_segcblist * rsclp)87 static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
88 {
89 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
90 rcu_segcblist_test_flags(rsclp, SEGCBLIST_LOCKING))
91 return true;
92
93 return false;
94 }
95
rcu_segcblist_completely_offloaded(struct rcu_segcblist * rsclp)96 static inline bool rcu_segcblist_completely_offloaded(struct rcu_segcblist *rsclp)
97 {
98 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
99 !rcu_segcblist_test_flags(rsclp, SEGCBLIST_RCU_CORE))
100 return true;
101
102 return false;
103 }
104
105 /*
106 * Are all segments following the specified segment of the specified
107 * rcu_segcblist structure empty of callbacks? (The specified
108 * segment might well contain callbacks.)
109 */
rcu_segcblist_restempty(struct rcu_segcblist * rsclp,int seg)110 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
111 {
112 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
113 }
114
115 /*
116 * Is the specified segment of the specified rcu_segcblist structure
117 * empty of callbacks?
118 */
rcu_segcblist_segempty(struct rcu_segcblist * rsclp,int seg)119 static inline bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg)
120 {
121 if (seg == RCU_DONE_TAIL)
122 return &rsclp->head == rsclp->tails[RCU_DONE_TAIL];
123 return rsclp->tails[seg - 1] == rsclp->tails[seg];
124 }
125
126 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
127 void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v);
128 void rcu_segcblist_init(struct rcu_segcblist *rsclp);
129 void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
130 void rcu_segcblist_offload(struct rcu_segcblist *rsclp, bool offload);
131 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
132 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
133 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
134 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
135 bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
136 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
137 struct rcu_head *rhp);
138 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
139 struct rcu_head *rhp);
140 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
141 struct rcu_cblist *rclp);
142 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
143 struct rcu_cblist *rclp);
144 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
145 struct rcu_cblist *rclp);
146 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
147 struct rcu_cblist *rclp);
148 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
149 struct rcu_cblist *rclp);
150 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
151 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
152 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
153 struct rcu_segcblist *src_rsclp);
154