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       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                 :          3 :         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                 :          3 :         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                 :          3 :         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                 :          0 :         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                 :          3 :         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                 :          3 :         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                 :          3 :         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);