kernel/rcu/rcu_segcblist.h

   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 bool rcu_segcblist_future_gp_needed(struct rcu_segcblist *rsclp,
 138                                     unsigned long seq);
 139 void rcu_segcblist_merge(struct rcu_segcblist *dst_rsclp,
 140                          struct rcu_segcblist *src_rsclp);