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