Implement list.h wrapper for hlist in older kernels

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

diff --git a/wrapper/list.h b/wrapper/list.h
new file mode 100644 (file)
index 0000000..c816684
--- /dev/null
+++ b/wrapper/list.h
@@ -0,0 +1,84 @@
+#ifndef _LTTNG_WRAPPER_LIST_H
+#define _LTTNG_WRAPPER_LIST_H
+
+/*
+ * wrapper/list.h
+ *
+ * wrapper around linux/list.h.
+ *
+ * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; only version 2 of the License.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * This wrapper code is derived from Linux 3.19.2 include/linux/list.h
+ * and include/linux/rculist.h, hence the GPLv2 license applied to this
+ * file.
+ */
+
+#include <linux/list.h>
+#include <linux/rculist.h>
+
+#define lttng_hlist_entry_safe(ptr, type, member) \
+       ({ typeof(ptr) ____ptr = (ptr); \
+          ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
+       })
+
+/**
+ * lttng_hlist_for_each_entry  - iterate over list of given type
+ * @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.
+ */
+#define lttng_hlist_for_each_entry(pos, head, member)                  \
+       for (pos = lttng_hlist_entry_safe((head)->first, typeof(*(pos)), member);\
+            pos;                                                       \
+            pos = lttng_hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
+
+/**
+ * lttng_hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
+ * @pos:       the type * to use as a loop cursor.
+ * @n:         another &struct hlist_node to use as temporary storage
+ * @head:      the head for your list.
+ * @member:    the name of the hlist_node within the struct.
+ */
+#define lttng_hlist_for_each_entry_safe(pos, n, head, member)          \
+       for (pos = lttng_hlist_entry_safe((head)->first, typeof(*pos), member);\
+            pos && ({ n = pos->member.next; 1; });                     \
+            pos = lttng_hlist_entry_safe(n, typeof(*pos), member))
+
+#ifndef rcu_dereference_raw_notrace
+#define rcu_dereference_raw_notrace(p) rcu_dereference_raw(p)
+#endif
+
+/**
+ * lttng_hlist_for_each_entry_rcu_notrace - 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_notrace(pos, head, member)      \
+       for (pos = lttng_hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\
+                       typeof(*(pos)), member);                        \
+               pos;                                                    \
+               pos = lttng_hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\
+                       &(pos)->member)), typeof(*(pos)), member))
+
+#endif /* _LTTNG_WRAPPER_LIST_H */