Fix: add lttng rcu wrapper to allow tracing RCU

[lttng-modules.git] / wrapper / rcu.h

diff --git a/wrapper/rcu.h b/wrapper/rcu.h
new file mode 100644 (file)
index 0000000..d96d42d
--- /dev/null
+++ b/wrapper/rcu.h
@@ -0,0 +1,90 @@
+#ifndef _LTTNG_WRAPPER_RCU_H
+#define _LTTNG_WRAPPER_RCU_H
+
+/*
+ * wrapper/rcu.h
+ *
+ * wrapper around linux/rcupdate.h and linux/rculist.h.
+ *
+ * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/version.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include "list.h"
+
+#ifndef rcu_dereference_raw_notrace
+#define rcu_dereference_raw_notrace(p) rcu_dereference_raw(p)
+#endif
+
+#define lttng_rcu_dereference(p) rcu_dereference_raw_notrace(p)
+
+/**
+ * lttng_list_entry_rcu - get the struct for this entry
+ * @ptr:        the &struct list_head pointer.
+ * @type:       the type of the struct this is embedded in.
+ * @member:     the name of the list_head within the struct.
+ *
+ * This primitive may safely run concurrently with the _rcu list-mutation
+ * primitives such as list_add_rcu() as long as it's guarded by
+ * rcu_read_lock_sched().
+ * Can be used while tracing RCU.
+ */
+#define lttng_list_entry_rcu(ptr, type, member) \
+({ \
+       typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
+       container_of((typeof(ptr))lttng_rcu_dereference(__ptr), type, member); \
+})
+
+/**
+ * lttng_list_for_each_entry_rcu - iterate over rcu list of given type
+ * @pos:       the type * to use as a loop cursor.
+ * @head:      the head for your list.
+ * @member:    the name of the list_head within the struct.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as list_add_rcu()
+ * as long as the traversal is guarded by rcu_read_lock_sched().
+ * Can be used while tracing RCU.
+ */
+#define lttng_list_for_each_entry_rcu(pos, head, member) \
+       for (pos = lttng_list_entry_rcu((head)->next, typeof(*pos), member); \
+               &pos->member != (head); \
+               pos = lttng_list_entry_rcu(pos->member.next, typeof(*pos), member))
+
+/**
+ * lttng_hlist_for_each_entry_rcu - iterate over rcu list of given type (for tracing)
+ * @pos:       the type * to use as a loop cursor.
+ * @head:      the head for your list.
+ * @member:    the name of the hlist_node within the struct.
+ *
+ * This list-traversal primitive may safely run concurrently with
+ * the _rcu list-mutation primitives such as hlist_add_head_rcu()
+ * as long as the traversal is guarded by rcu_read_lock().
+ *
+ * This is the same as hlist_for_each_entry_rcu() except that it does
+ * not do any RCU debugging or tracing.
+ */
+#define lttng_hlist_for_each_entry_rcu(pos, head, member)      \
+       for (pos = lttng_hlist_entry_safe (lttng_rcu_dereference(hlist_first_rcu(head)), \
+                       typeof(*(pos)), member);                \
+               pos;                                            \
+               pos = lttng_hlist_entry_safe(lttng_rcu_dereference(hlist_next_rcu( \
+                       &(pos)->member)), typeof(*(pos)), member))
+
+#endif /* _LTTNG_WRAPPER_RCU_H */