wrapper/rcu.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * wrapper/rcu.h
   4  *
   5  * wrapper around linux/rcupdate.h and linux/rculist.h.
   6  *
   7  * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #ifndef _LTTNG_WRAPPER_RCU_H
  11 #define _LTTNG_WRAPPER_RCU_H
  12
  13 #include <linux/version.h>
  14 #include <linux/rculist.h>
  15 #include <linux/rcupdate.h>
  16
  17 #ifndef rcu_dereference_raw_notrace
  18 #define rcu_dereference_raw_notrace(p)  rcu_dereference_raw(p)
  19 #endif
  20
  21 #define lttng_rcu_dereference(p) rcu_dereference_raw_notrace(p)
  22
  23 /**
  24  * lttng_list_entry_rcu - get the struct for this entry
  25  * @ptr:        the &struct list_head pointer.
  26  * @type:       the type of the struct this is embedded in.
  27  * @member:     the name of the list_head within the struct.
  28  *
  29  * This primitive may safely run concurrently with the _rcu list-mutation
  30  * primitives such as list_add_rcu() as long as it's guarded by
  31  * rcu_read_lock_sched().
  32  * Can be used while tracing RCU.
  33  */
  34 #define lttng_list_entry_rcu(ptr, type, member) \
  35 ({ \
  36         typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
  37         container_of((typeof(ptr))lttng_rcu_dereference(__ptr), type, member); \
  38 })
  39
  40 /**
  41  * lttng_list_for_each_entry_rcu - iterate over rcu list of given type
  42  * @pos:        the type * to use as a loop cursor.
  43  * @head:       the head for your list.
  44  * @member:     the name of the list_head within the struct.
  45  *
  46  * This list-traversal primitive may safely run concurrently with
  47  * the _rcu list-mutation primitives such as list_add_rcu()
  48  * as long as the traversal is guarded by rcu_read_lock_sched().
  49  * Can be used while tracing RCU.
  50  */
  51 #define lttng_list_for_each_entry_rcu(pos, head, member) \
  52         for (pos = lttng_list_entry_rcu((head)->next, typeof(*pos), member); \
  53                 &pos->member != (head); \
  54                 pos = lttng_list_entry_rcu(pos->member.next, typeof(*pos), member))
  55
  56 #endif /* _LTTNG_WRAPPER_RCU_H */