Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef _LINUX_RCULIST_BL_H
       3             : #define _LINUX_RCULIST_BL_H
       4             : 
       5             : /*
       6             :  * RCU-protected bl list version. See include/linux/list_bl.h.
       7             :  */
       8             : #include <linux/list_bl.h>
       9             : #include <linux/rcupdate.h>
      10             : 
      11             : static inline void hlist_bl_set_first_rcu(struct hlist_bl_head *h,
      12             :                                         struct hlist_bl_node *n)
      13             : {
      14             :         LIST_BL_BUG_ON((unsigned long)n & LIST_BL_LOCKMASK);
      15             :         LIST_BL_BUG_ON(((unsigned long)h->first & LIST_BL_LOCKMASK) !=
      16             :                                                         LIST_BL_LOCKMASK);
      17           5 :         rcu_assign_pointer(h->first,
      18             :                 (struct hlist_bl_node *)((unsigned long)n | LIST_BL_LOCKMASK));
      19             : }
      20             : 
      21             : static inline struct hlist_bl_node *hlist_bl_first_rcu(struct hlist_bl_head *h)
      22             : {
      23             :         return (struct hlist_bl_node *)
      24           4 :                 ((unsigned long)rcu_dereference_check(h->first, hlist_bl_is_locked(h)) & ~LIST_BL_LOCKMASK);
      25             : }
      26             : 
      27             : /**
      28             :  * hlist_bl_del_rcu - deletes entry from hash list without re-initialization
      29             :  * @n: the element to delete from the hash list.
      30             :  *
      31             :  * Note: hlist_bl_unhashed() on entry does not return true after this,
      32             :  * the entry is in an undefined state. It is useful for RCU based
      33             :  * lockfree traversal.
      34             :  *
      35             :  * In particular, it means that we can not poison the forward
      36             :  * pointers that may still be used for walking the hash list.
      37             :  *
      38             :  * The caller must take whatever precautions are necessary
      39             :  * (such as holding appropriate locks) to avoid racing
      40             :  * with another list-mutation primitive, such as hlist_bl_add_head_rcu()
      41             :  * or hlist_bl_del_rcu(), running on this same list.
      42             :  * However, it is perfectly legal to run concurrently with
      43             :  * the _rcu list-traversal primitives, such as
      44             :  * hlist_bl_for_each_entry().
      45             :  */
      46             : static inline void hlist_bl_del_rcu(struct hlist_bl_node *n)
      47             : {
      48             :         __hlist_bl_del(n);
      49             :         n->pprev = LIST_POISON2;
      50             : }
      51             : 
      52             : /**
      53             :  * hlist_bl_add_head_rcu
      54             :  * @n: the element to add to the hash list.
      55             :  * @h: the list to add to.
      56             :  *
      57             :  * Description:
      58             :  * Adds the specified element to the specified hlist_bl,
      59             :  * while permitting racing traversals.
      60             :  *
      61             :  * The caller must take whatever precautions are necessary
      62             :  * (such as holding appropriate locks) to avoid racing
      63             :  * with another list-mutation primitive, such as hlist_bl_add_head_rcu()
      64             :  * or hlist_bl_del_rcu(), running on this same list.
      65             :  * However, it is perfectly legal to run concurrently with
      66             :  * the _rcu list-traversal primitives, such as
      67             :  * hlist_bl_for_each_entry_rcu(), used to prevent memory-consistency
      68             :  * problems on Alpha CPUs.  Regardless of the type of CPU, the
      69             :  * list-traversal primitive must be guarded by rcu_read_lock().
      70             :  */
      71             : static inline void hlist_bl_add_head_rcu(struct hlist_bl_node *n,
      72             :                                         struct hlist_bl_head *h)
      73             : {
      74             :         struct hlist_bl_node *first;
      75             : 
      76             :         /* don't need hlist_bl_first_rcu because we're under lock */
      77           5 :         first = hlist_bl_first(h);
      78             : 
      79           5 :         n->next = first;
      80           5 :         if (first)
      81           0 :                 first->pprev = &n->next;
      82           5 :         n->pprev = &h->first;
      83             : 
      84             :         /* need _rcu because we can have concurrent lock free readers */
      85           5 :         hlist_bl_set_first_rcu(h, n);
      86             : }
      87             : /**
      88             :  * hlist_bl_for_each_entry_rcu - iterate over rcu list of given type
      89             :  * @tpos:       the type * to use as a loop cursor.
      90             :  * @pos:        the &struct hlist_bl_node to use as a loop cursor.
      91             :  * @head:       the head for your list.
      92             :  * @member:     the name of the hlist_bl_node within the struct.
      93             :  *
      94             :  */
      95             : #define hlist_bl_for_each_entry_rcu(tpos, pos, head, member)            \
      96             :         for (pos = hlist_bl_first_rcu(head);                            \
      97             :                 pos &&                                                  \
      98             :                 ({ tpos = hlist_bl_entry(pos, typeof(*tpos), member); 1; }); \
      99             :                 pos = rcu_dereference_raw(pos->next))
     100             : 
     101             : #endif