1 /* 2 * RCU segmented callback lists, internal-to-rcu header file 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, you can access it online at 16 * http://www.gnu.org/licenses/gpl-2.0.html. 17 * 18 * Copyright IBM Corporation, 2017 19 * 20 * Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 21 */ 22 23 #include <linux/rcu_segcblist.h> 24 25 /* 26 * Account for the fact that a previously dequeued callback turned out 27 * to be marked as lazy. 28 */ 29 static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp) 30 { 31 rclp->len_lazy--; 32 } 33 34 void rcu_cblist_init(struct rcu_cblist *rclp); 35 struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp); 36 37 /* 38 * Is the specified rcu_segcblist structure empty? 39 * 40 * But careful! The fact that the ->head field is NULL does not 41 * necessarily imply that there are no callbacks associated with 42 * this structure. When callbacks are being invoked, they are 43 * removed as a group. If callback invocation must be preempted, 44 * the remaining callbacks will be added back to the list. Either 45 * way, the counts are updated later. 46 * 47 * So it is often the case that rcu_segcblist_n_cbs() should be used 48 * instead. 49 */ 50 static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp) 51 { 52 return !rsclp->head; 53 } 54 55 /* Return number of callbacks in segmented callback list. */ 56 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp) 57 { 58 return READ_ONCE(rsclp->len); 59 } 60 61 /* Return number of lazy callbacks in segmented callback list. */ 62 static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp) 63 { 64 return rsclp->len_lazy; 65 } 66 67 /* Return number of lazy callbacks in segmented callback list. */ 68 static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp) 69 { 70 return rsclp->len - rsclp->len_lazy; 71 } 72 73 /* 74 * Is the specified rcu_segcblist enabled, for example, not corresponding 75 * to an offline or callback-offloaded CPU? 76 */ 77 static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp) 78 { 79 return !!rsclp->tails[RCU_NEXT_TAIL]; 80 } 81 82 /* 83 * Are all segments following the specified segment of the specified 84 * rcu_segcblist structure empty of callbacks? (The specified 85 * segment might well contain callbacks.) 86 */ 87 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg) 88 { 89 return !*rsclp->tails[seg]; 90 } 91 92 /* 93 * Interim function to return rcu_segcblist head pointer. Longer term, the 94 * rcu_segcblist will be used more pervasively, removing the need for this 95 * function. 96 */ 97 static inline struct rcu_head *rcu_segcblist_head(struct rcu_segcblist *rsclp) 98 { 99 return rsclp->head; 100 } 101 102 /* 103 * Interim function to return rcu_segcblist head pointer. Longer term, the 104 * rcu_segcblist will be used more pervasively, removing the need for this 105 * function. 106 */ 107 static inline struct rcu_head **rcu_segcblist_tail(struct rcu_segcblist *rsclp) 108 { 109 WARN_ON_ONCE(rcu_segcblist_empty(rsclp)); 110 return rsclp->tails[RCU_NEXT_TAIL]; 111 } 112 113 void rcu_segcblist_init(struct rcu_segcblist *rsclp); 114 void rcu_segcblist_disable(struct rcu_segcblist *rsclp); 115 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp); 116 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp); 117 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp); 118 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp); 119 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, 120 struct rcu_head *rhp, bool lazy); 121 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, 122 struct rcu_head *rhp, bool lazy); 123 void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp, 124 struct rcu_cblist *rclp); 125 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp, 126 struct rcu_cblist *rclp); 127 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp, 128 struct rcu_cblist *rclp); 129 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp, 130 struct rcu_cblist *rclp); 131 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp, 132 struct rcu_cblist *rclp); 133 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, 134 struct rcu_cblist *rclp); 135 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq); 136 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq); 137 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp, 138 struct rcu_segcblist *src_rsclp); 139