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authorMatthew Wilcox <willy@infradead.org>2017-11-07 16:30:10 -0500
committerMatthew Wilcox <willy@infradead.org>2018-10-21 10:45:53 -0400
commitf8d5d0cc145cc21bfc56ef807dc28102aebbf228 (patch)
tree0fcba575e83fb02fd2cb49df1ce1cc55bcd927d3 /include/linux/xarray.h
parent02c02bf12c5d838603eed44195d3e91f094e2ab2 (diff)
downloadlinux-stericsson-f8d5d0cc145cc21bfc56ef807dc28102aebbf228.tar.gz
xarray: Add definition of struct xarray
This is a direct replacement for struct radix_tree_root. Some of the struct members have changed name; convert those, and use a #define so that radix_tree users continue to work without change. Signed-off-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Josef Bacik <jbacik@fb.com>
Diffstat (limited to 'include/linux/xarray.h')
-rw-r--r--include/linux/xarray.h70
1 files changed, 70 insertions, 0 deletions
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 4d1cd7a083e8..9122cf8bf52a 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -10,6 +10,8 @@
*/
#include <linux/bug.h>
+#include <linux/compiler.h>
+#include <linux/kconfig.h>
#include <linux/spinlock.h>
#include <linux/types.h>
@@ -153,6 +155,74 @@ static inline bool xa_is_internal(const void *entry)
return ((unsigned long)entry & 3) == 2;
}
+/**
+ * struct xarray - The anchor of the XArray.
+ * @xa_lock: Lock that protects the contents of the XArray.
+ *
+ * To use the xarray, define it statically or embed it in your data structure.
+ * It is a very small data structure, so it does not usually make sense to
+ * allocate it separately and keep a pointer to it in your data structure.
+ *
+ * You may use the xa_lock to protect your own data structures as well.
+ */
+/*
+ * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
+ * If the only non-NULL entry in the array is at index 0, @xa_head is that
+ * entry. If any other entry in the array is non-NULL, @xa_head points
+ * to an @xa_node.
+ */
+struct xarray {
+ spinlock_t xa_lock;
+/* private: The rest of the data structure is not to be used directly. */
+ gfp_t xa_flags;
+ void __rcu * xa_head;
+};
+
+#define XARRAY_INIT(name, flags) { \
+ .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock), \
+ .xa_flags = flags, \
+ .xa_head = NULL, \
+}
+
+/**
+ * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
+ * @name: A string that names your XArray.
+ * @flags: XA_FLAG values.
+ *
+ * This is intended for file scope definitions of XArrays. It declares
+ * and initialises an empty XArray with the chosen name and flags. It is
+ * equivalent to calling xa_init_flags() on the array, but it does the
+ * initialisation at compiletime instead of runtime.
+ */
+#define DEFINE_XARRAY_FLAGS(name, flags) \
+ struct xarray name = XARRAY_INIT(name, flags)
+
+/**
+ * DEFINE_XARRAY() - Define an XArray.
+ * @name: A string that names your XArray.
+ *
+ * This is intended for file scope definitions of XArrays. It declares
+ * and initialises an empty XArray with the chosen name. It is equivalent
+ * to calling xa_init() on the array, but it does the initialisation at
+ * compiletime instead of runtime.
+ */
+#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
+
+void xa_init_flags(struct xarray *, gfp_t flags);
+
+/**
+ * xa_init() - Initialise an empty XArray.
+ * @xa: XArray.
+ *
+ * An empty XArray is full of NULL entries.
+ *
+ * Context: Any context.
+ */
+static inline void xa_init(struct xarray *xa)
+{
+ xa_init_flags(xa, 0);
+}
+
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
#define xa_lock(xa) spin_lock(&(xa)->xa_lock)
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)