wrapper/rcu.h

   1 #ifndef _LTTNG_WRAPPER_RCU_H
   2 #define _LTTNG_WRAPPER_RCU_H
   3
   4 /*
   5  * wrapper/rcu.h
   6  *
   7  * wrapper around linux/rcupdate.h and linux/rculist.h.
   8  *
   9  * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; only
  14  * version 2.1 of the License.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <linux/version.h>
  27 #include <linux/rculist.h>
  28 #include <linux/rcupdate.h>
  29 #include <wrapper/list.h>
  30
  31 #ifndef rcu_dereference_raw_notrace
  32 #define rcu_dereference_raw_notrace(p)  rcu_dereference_raw(p)
  33 #endif
  34
  35 #define lttng_rcu_dereference(p) rcu_dereference_raw_notrace(p)
  36
  37 /**
  38  * lttng_list_entry_rcu - get the struct for this entry
  39  * @ptr:        the &struct list_head pointer.
  40  * @type:       the type of the struct this is embedded in.
  41  * @member:     the name of the list_head within the struct.
  42  *
  43  * This primitive may safely run concurrently with the _rcu list-mutation
  44  * primitives such as list_add_rcu() as long as it's guarded by
  45  * rcu_read_lock_sched().
  46  * Can be used while tracing RCU.
  47  */
  48 #define lttng_list_entry_rcu(ptr, type, member) \
  49 ({ \
  50         typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
  51         container_of((typeof(ptr))lttng_rcu_dereference(__ptr), type, member); \
  52 })
  53
  54 /**
  55  * lttng_list_for_each_entry_rcu - iterate over rcu list of given type
  56  * @pos:        the type * to use as a loop cursor.
  57  * @head:       the head for your list.
  58  * @member:     the name of the list_head within the struct.
  59  *
  60  * This list-traversal primitive may safely run concurrently with
  61  * the _rcu list-mutation primitives such as list_add_rcu()
  62  * as long as the traversal is guarded by rcu_read_lock_sched().
  63  * Can be used while tracing RCU.
  64  */
  65 #define lttng_list_for_each_entry_rcu(pos, head, member) \
  66         for (pos = lttng_list_entry_rcu((head)->next, typeof(*pos), member); \
  67                 &pos->member != (head); \
  68                 pos = lttng_list_entry_rcu(pos->member.next, typeof(*pos), member))
  69
  70 /**
  71  * lttng_hlist_for_each_entry_rcu - iterate over rcu list of given type (for tracing)
  72  * @pos:        the type * to use as a loop cursor.
  73  * @head:       the head for your list.
  74  * @member:     the name of the hlist_node within the struct.
  75  *
  76  * This list-traversal primitive may safely run concurrently with
  77  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
  78  * as long as the traversal is guarded by rcu_read_lock().
  79  *
  80  * This is the same as hlist_for_each_entry_rcu() except that it does
  81  * not do any RCU debugging or tracing.
  82  */
  83 #define lttng_hlist_for_each_entry_rcu(pos, head, member)       \
  84         for (pos = lttng_hlist_entry_safe (lttng_rcu_dereference(lttng_hlist_first_rcu(head)), \
  85                         typeof(*(pos)), member);                \
  86                 pos;                                            \
  87                 pos = lttng_hlist_entry_safe(lttng_rcu_dereference(lttng_hlist_next_rcu( \
  88                         &(pos)->member)), typeof(*(pos)), member))
  89
  90 #endif /* _LTTNG_WRAPPER_RCU_H */