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 /* Return number of callbacks in segmented callback list by summing seglen. */ 19 long rcu_segcblist_n_segment_cbs(struct rcu_segcblist *rsclp); 20 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); 27 28 /* 29 * Is the specified rcu_segcblist structure empty? 30 * 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. 37 * 38 * So it is often the case that rcu_segcblist_n_cbs() should be used 39 * instead. 40 */ 41 static inline bool rcu_segcblist_empty(struct rcu_segcblist *rsclp) 42 { 43 return !READ_ONCE(rsclp->head); 44 } 45 46 /* Return number of callbacks in segmented callback list. */ 47 static inline long rcu_segcblist_n_cbs(struct rcu_segcblist *rsclp) 48 { 49 #ifdef CONFIG_RCU_NOCB_CPU 50 return atomic_long_read(&rsclp->len); 51 #else 52 return READ_ONCE(rsclp->len); 53 #endif 54 } 55 56 static inline void rcu_segcblist_set_flags(struct rcu_segcblist *rsclp, 57 int flags) 58 { 59 rsclp->flags |= flags; 60 } 61 62 static inline void rcu_segcblist_clear_flags(struct rcu_segcblist *rsclp, 63 int flags) 64 { 65 rsclp->flags &= ~flags; 66 } 67 68 static inline bool rcu_segcblist_test_flags(struct rcu_segcblist *rsclp, 69 int flags) 70 { 71 return READ_ONCE(rsclp->flags) & flags; 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 rcu_segcblist_test_flags(rsclp, SEGCBLIST_ENABLED); 81 } 82 83 /* 84 * Is the specified rcu_segcblist NOCB offloaded (or in the middle of the 85 * [de]offloading process)? 86 */ 87 static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp) 88 { 89 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) && 90 rcu_segcblist_test_flags(rsclp, SEGCBLIST_LOCKING)) 91 return true; 92 93 return false; 94 } 95 96 static inline bool rcu_segcblist_completely_offloaded(struct rcu_segcblist *rsclp) 97 { 98 if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) && 99 !rcu_segcblist_test_flags(rsclp, SEGCBLIST_RCU_CORE)) 100 return true; 101 102 return false; 103 } 104 105 /* 106 * Are all segments following the specified segment of the specified 107 * rcu_segcblist structure empty of callbacks? (The specified 108 * segment might well contain callbacks.) 109 */ 110 static inline bool rcu_segcblist_restempty(struct rcu_segcblist *rsclp, int seg) 111 { 112 return !READ_ONCE(*READ_ONCE(rsclp->tails[seg])); 113 } 114 115 /* 116 * Is the specified segment of the specified rcu_segcblist structure 117 * empty of callbacks? 118 */ 119 static inline bool rcu_segcblist_segempty(struct rcu_segcblist *rsclp, int seg) 120 { 121 if (seg == RCU_DONE_TAIL) 122 return &rsclp->head == rsclp->tails[RCU_DONE_TAIL]; 123 return rsclp->tails[seg - 1] == rsclp->tails[seg]; 124 } 125 126 void rcu_segcblist_inc_len(struct rcu_segcblist *rsclp); 127 void rcu_segcblist_add_len(struct rcu_segcblist *rsclp, long v); 128 void rcu_segcblist_init(struct rcu_segcblist *rsclp); 129 void rcu_segcblist_disable(struct rcu_segcblist *rsclp); 130 void rcu_segcblist_offload(struct rcu_segcblist *rsclp, bool offload); 131 bool rcu_segcblist_ready_cbs(struct rcu_segcblist *rsclp); 132 bool rcu_segcblist_pend_cbs(struct rcu_segcblist *rsclp); 133 struct rcu_head *rcu_segcblist_first_cb(struct rcu_segcblist *rsclp); 134 struct rcu_head *rcu_segcblist_first_pend_cb(struct rcu_segcblist *rsclp); 135 bool rcu_segcblist_nextgp(struct rcu_segcblist *rsclp, unsigned long *lp); 136 void rcu_segcblist_enqueue(struct rcu_segcblist *rsclp, 137 struct rcu_head *rhp); 138 bool rcu_segcblist_entrain(struct rcu_segcblist *rsclp, 139 struct rcu_head *rhp); 140 void rcu_segcblist_extract_done_cbs(struct rcu_segcblist *rsclp, 141 struct rcu_cblist *rclp); 142 void rcu_segcblist_extract_pend_cbs(struct rcu_segcblist *rsclp, 143 struct rcu_cblist *rclp); 144 void rcu_segcblist_insert_count(struct rcu_segcblist *rsclp, 145 struct rcu_cblist *rclp); 146 void rcu_segcblist_insert_done_cbs(struct rcu_segcblist *rsclp, 147 struct rcu_cblist *rclp); 148 void rcu_segcblist_insert_pend_cbs(struct rcu_segcblist *rsclp, 149 struct rcu_cblist *rclp); 150 void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq); 151 bool rcu_segcblist_accelerate(struct rcu_segcblist *rsclp, unsigned long seq); 152 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp, 153 struct rcu_segcblist *src_rsclp); 154