1 /* SPDX-License-Identifier: GPL-2.0+ */
3 * RCU segmented callback lists, internal-to-rcu header file
5 * Copyright IBM Corporation, 2017
7 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
10 #include <linux/rcu_segcblist.h>
12 /* Return number of callbacks in the specified callback list. */
13 static inline long rcu_cblist_n_cbs(struct rcu_cblist *rclp)
15 return READ_ONCE(rclp->len);
18 /* Return number of callbacks in segmented callback list by summing seglen. */
19 long rcu_segcblist_n_segment_cbs(struct rcu_segcblist *rsclp);
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);
29 * Is the specified rcu_segcblist structure empty?
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.
38 * So it is often the case that rcu_segcblist_n_cbs() should be used
41 static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp)
43 return !READ_ONCE(rsclp->head);
46 /* Return number of callbacks in segmented callback list. */
47 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp)
49 #ifdef CONFIG_RCU_NOCB_CPU
50 return atomic_long_read(&rsclp->len);
52 return READ_ONCE(rsclp->len);
56 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp,
59 WRITE_ONCE(rsclp->flags, rsclp->flags | flags);
62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp,
65 WRITE_ONCE(rsclp->flags, rsclp->flags & ~flags);
68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp,
71 return READ_ONCE(rsclp->flags) & flags;
75 * Is the specified rcu_segcblist enabled, for example, not corresponding
78 static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
80 return rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED);
83 /* Is the specified rcu_segcblist offloaded, or is SEGCBLIST_SOFTIRQ_ONLY set? */
84 static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
86 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
87 !rcu_segcblist_test_flags(rsclp, SEGCBLIST_SOFTIRQ_ONLY))
93 static inline bool rcu_segcblist_completely_offloaded(struct rcu_segcblist *rsclp)
95 int flags = SEGCBLIST_KTHREAD_CB | SEGCBLIST_KTHREAD_GP | SEGCBLIST_OFFLOADED;
97 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) && (rsclp->flags & flags) == flags)
104 * Are all segments following the specified segment of the specified
105 * rcu_segcblist structure empty of callbacks? (The specified
106 * segment might well contain callbacks.)
108 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg)
110 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg]));
114 * Is the specified segment of the specified rcu_segcblist structure
115 * empty of callbacks?
117 static inline bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg)
119 if (seg == RCU_DONE_TAIL)
120 return &rsclp->head == rsclp->tails[RCU_DONE_TAIL];
121 return rsclp->tails[seg - 1] == rsclp->tails[seg];
124 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp);
125 void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v);
126 void rcu_segcblist_init(struct rcu_segcblist *rsclp);
127 void rcu_segcblist_disable(struct rcu_segcblist *rsclp);
128 void rcu_segcblist_offload(struct rcu_segcblist *rsclp, bool offload);
129 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp);
130 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp);
131 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp);
132 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp);
133 bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp);
134 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp,
135 struct rcu_head *rhp);
136 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp,
137 struct rcu_head *rhp);
138 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp,
139 struct rcu_cblist *rclp);
140 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp,
141 struct rcu_cblist *rclp);
142 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp,
143 struct rcu_cblist *rclp);
144 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp,
145 struct rcu_cblist *rclp);
146 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp,
147 struct rcu_cblist *rclp);
148 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq);
149 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq);
150 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
151 struct rcu_segcblist *src_rsclp);