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 /* 19 * Account for the fact that a previously dequeued callback turned out 20 * to be marked as lazy. 21 */ 22 static inline void rcu_cblist_dequeued_lazy(struct rcu_cblist *rclp) 23 { 24 rclp->len_lazy--; 25 } 26 27 void rcu_cblist_init(struct rcu_cblist *rclp); 28 void rcu_cblist_enqueue(struct rcu_cblist *rclp, struct rcu_head *rhp); 29 void rcu_cblist_flush_enqueue(struct rcu_cblist *drclp, 30 struct rcu_cblist *srclp, 31 struct rcu_head *rhp); 32 struct rcu_head *rcu_cblist_dequeue(struct rcu_cblist *rclp); 33 34 /* 35 * Is the specified rcu_segcblist structure empty? 36 * 37 * But careful! The fact that the ->head field is NULL does not 38 * necessarily imply that there are no callbacks associated with 39 * this structure. When callbacks are being invoked, they are 40 * removed as a group. If callback invocation must be preempted, 41 * the remaining callbacks will be added back to the list. Either 42 * way, the counts are updated later. 43 * 44 * So it is often the case that rcu_segcblist_n_cbs() should be used 45 * instead. 46 */ 47 static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp) 48 { 49 return !READ_ONCE(rsclp->head); 50 } 51 52 /* Return number of callbacks in segmented callback list. */ 53 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp) 54 { 55 #ifdef CONFIG_RCU_NOCB_CPU 56 return atomic_long_read(&rsclp->len); 57 #else 58 return READ_ONCE(rsclp->len); 59 #endif 60 } 61 62 /* Return number of lazy callbacks in segmented callback list. */ 63 static inline long rcu_segcblist_n_lazy_cbs(struct rcu_segcblist *rsclp) 64 { 65 return rsclp->len_lazy; 66 } 67 68 /* Return number of lazy callbacks in segmented callback list. */ 69 static inline long rcu_segcblist_n_nonlazy_cbs(struct rcu_segcblist *rsclp) 70 { 71 return rcu_segcblist_n_cbs(rsclp) - rsclp->len_lazy; 72 } 73 74 /* 75 * Is the specified rcu_segcblist enabled, for example, not corresponding 76 * to an offline CPU? 77 */ 78 static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp) 79 { 80 return rsclp->enabled; 81 } 82 83 /* Is the specified rcu_segcblist offloaded? */ 84 static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp) 85 { 86 return rsclp->offloaded; 87 } 88 89 /* 90 * Are all segments following the specified segment of the specified 91 * rcu_segcblist structure empty of callbacks? (The specified 92 * segment might well contain callbacks.) 93 */ 94 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg) 95 { 96 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg])); 97 } 98 99 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp); 100 void rcu_segcblist_init(struct rcu_segcblist *rsclp); 101 void rcu_segcblist_disable(struct rcu_segcblist *rsclp); 102 void rcu_segcblist_offload(struct rcu_segcblist *rsclp); 103 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp); 104 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp); 105 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp); 106 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp); 107 bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp); 108 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, 109 struct rcu_head *rhp, bool lazy); 110 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, 111 struct rcu_head *rhp, bool lazy); 112 void rcu_segcblist_extract_count(struct rcu_segcblist *rsclp, 113 struct rcu_cblist *rclp); 114 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp, 115 struct rcu_cblist *rclp); 116 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp, 117 struct rcu_cblist *rclp); 118 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp, 119 struct rcu_cblist *rclp); 120 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp, 121 struct rcu_cblist *rclp); 122 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, 123 struct rcu_cblist *rclp); 124 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq); 125 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq); 126 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp, 127 struct rcu_segcblist *src_rsclp); 128