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 /* 13 * Account for the fact that a previously dequeued callback turned out 14 * to be marked as lazy. 15 */ 16 static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp) 17 { 18 rclp->len_lazy--; 19 } 20 21 void rcu_cblist_init(struct rcu_cblist *rclp); 22 struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp); 23 24 /* 25 * Is the specified rcu_segcblist structure empty? 26 * 27 * But careful! The fact that the ->head field is NULL does not 28 * necessarily imply that there are no callbacks associated with 29 * this structure. When callbacks are being invoked, they are 30 * removed as a group. If callback invocation must be preempted, 31 * the remaining callbacks will be added back to the list. Either 32 * way, the counts are updated later. 33 * 34 * So it is often the case that rcu_segcblist_n_cbs() should be used 35 * instead. 36 */ 37 static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp) 38 { 39 return !rsclp->head; 40 } 41 42 /* Return number of callbacks in segmented callback list. */ 43 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp) 44 { 45 return READ_ONCE(rsclp->len); 46 } 47 48 /* Return number of lazy callbacks in segmented callback list. */ 49 static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp) 50 { 51 return rsclp->len_lazy; 52 } 53 54 /* Return number of lazy callbacks in segmented callback list. */ 55 static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp) 56 { 57 return rsclp->len - rsclp->len_lazy; 58 } 59 60 /* 61 * Is the specified rcu_segcblist enabled, for example, not corresponding 62 * to an offline or callback-offloaded CPU? 63 */ 64 static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp) 65 { 66 return !!rsclp->tails[RCU_NEXT_TAIL]; 67 } 68 69 /* 70 * Are all segments following the specified segment of the specified 71 * rcu_segcblist structure empty of callbacks? (The specified 72 * segment might well contain callbacks.) 73 */ 74 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg) 75 { 76 return !*rsclp->tails[seg]; 77 } 78 79 /* 80 * Interim function to return rcu_segcblist head pointer. Longer term, the 81 * rcu_segcblist will be used more pervasively, removing the need for this 82 * function. 83 */ 84 static inline struct rcu_head *rcu_segcblist_head(struct rcu_segcblist *rsclp) 85 { 86 return rsclp->head; 87 } 88 89 /* 90 * Interim function to return rcu_segcblist head pointer. Longer term, the 91 * rcu_segcblist will be used more pervasively, removing the need for this 92 * function. 93 */ 94 static inline struct rcu_head **rcu_segcblist_tail(struct rcu_segcblist *rsclp) 95 { 96 WARN_ON_ONCE(rcu_segcblist_empty(rsclp)); 97 return rsclp->tails[RCU_NEXT_TAIL]; 98 } 99 100 void rcu_segcblist_init(struct rcu_segcblist *rsclp); 101 void rcu_segcblist_disable(struct rcu_segcblist *rsclp); 102 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp); 103 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp); 104 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp); 105 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp); 106 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, 107 struct rcu_head *rhp, bool lazy); 108 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, 109 struct rcu_head *rhp, bool lazy); 110 void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp, 111 struct rcu_cblist *rclp); 112 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp, 113 struct rcu_cblist *rclp); 114 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp, 115 struct rcu_cblist *rclp); 116 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp, 117 struct rcu_cblist *rclp); 118 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp, 119 struct rcu_cblist *rclp); 120 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, 121 struct rcu_cblist *rclp); 122 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq); 123 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq); 124 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp, 125 struct rcu_segcblist *src_rsclp); 126