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2024-02-19 1c055e55a242a33e574e48be530e06770a210dcd

 kernel/include/linux/xarray.h
..
..
@@ -4,10 +4,525 @@
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 /*
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  * eXtensible Arrays
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  * Copyright (c) 2017 Microsoft Corporation
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- * Author: Matthew Wilcox <mawilcox@microsoft.com>
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+ * Author: Matthew Wilcox <willy@infradead.org>
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+ *
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+ * See Documentation/core-api/xarray.rst for how to use the XArray.
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  */
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11
 
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+#include <linux/bug.h>
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+#include <linux/compiler.h>
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+#include <linux/gfp.h>
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+#include <linux/kconfig.h>
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+#include <linux/kernel.h>
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+#include <linux/rcupdate.h>
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 #include <linux/spinlock.h>
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+#include <linux/types.h>
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+
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+/*
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+ * The bottom two bits of the entry determine how the XArray interprets
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+ * the contents:
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+ *
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+ * 00: Pointer entry
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+ * 10: Internal entry
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+ * x1: Value entry or tagged pointer
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+ *
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+ * Attempting to store internal entries in the XArray is a bug.
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+ *
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+ * Most internal entries are pointers to the next node in the tree.
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+ * The following internal entries have a special meaning:
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+ *
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+ * 0-62: Sibling entries
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+ * 256: Retry entry
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+ * 257: Zero entry
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+ *
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+ * Errors are also represented as internal entries, but use the negative
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+ * space (-4094 to -2).  They're never stored in the slots array; only
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+ * returned by the normal API.
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+ */
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+
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+#define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
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+
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+/**
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+ * xa_mk_value() - Create an XArray entry from an integer.
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+ * @v: Value to store in XArray.
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+ *
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+ * Context: Any context.
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+ * Return: An entry suitable for storing in the XArray.
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+ */
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+static inline void *xa_mk_value(unsigned long v)
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+{
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+	WARN_ON((long)v < 0);
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+	return (void *)((v << 1) | 1);
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+}
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+
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+/**
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+ * xa_to_value() - Get value stored in an XArray entry.
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+ * @entry: XArray entry.
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+ *
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+ * Context: Any context.
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+ * Return: The value stored in the XArray entry.
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+ */
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+static inline unsigned long xa_to_value(const void *entry)
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+{
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+	return (unsigned long)entry >> 1;
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+}
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+
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+/**
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+ * xa_is_value() - Determine if an entry is a value.
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+ * @entry: XArray entry.
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+ *
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+ * Context: Any context.
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+ * Return: True if the entry is a value, false if it is a pointer.
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+ */
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+static inline bool xa_is_value(const void *entry)
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+{
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+	return (unsigned long)entry & 1;
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+}
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+
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+/**
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+ * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
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+ * @p: Plain pointer.
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+ * @tag: Tag value (0, 1 or 3).
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+ *
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+ * If the user of the XArray prefers, they can tag their pointers instead
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+ * of storing value entries.  Three tags are available (0, 1 and 3).
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+ * These are distinct from the xa_mark_t as they are not replicated up
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+ * through the array and cannot be searched for.
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+ *
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+ * Context: Any context.
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+ * Return: An XArray entry.
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+ */
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+static inline void *xa_tag_pointer(void *p, unsigned long tag)
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+{
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+	return (void *)((unsigned long)p | tag);
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+}
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+
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+/**
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+ * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
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+ * @entry: XArray entry.
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+ *
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+ * If you have stored a tagged pointer in the XArray, call this function
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+ * to get the untagged version of the pointer.
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+ *
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+ * Context: Any context.
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+ * Return: A pointer.
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+ */
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+static inline void *xa_untag_pointer(void *entry)
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+{
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+	return (void *)((unsigned long)entry & ~3UL);
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+}
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+
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+/**
116
+ * xa_pointer_tag() - Get the tag stored in an XArray entry.
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+ * @entry: XArray entry.
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+ *
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+ * If you have stored a tagged pointer in the XArray, call this function
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+ * to get the tag of that pointer.
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+ *
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+ * Context: Any context.
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+ * Return: A tag.
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+ */
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+static inline unsigned int xa_pointer_tag(void *entry)
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+{
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+	return (unsigned long)entry & 3UL;
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+}
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+
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+/*
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+ * xa_mk_internal() - Create an internal entry.
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+ * @v: Value to turn into an internal entry.
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+ *
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+ * Internal entries are used for a number of purposes.  Entries 0-255 are
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+ * used for sibling entries (only 0-62 are used by the current code).  256
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+ * is used for the retry entry.  257 is used for the reserved / zero entry.
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+ * Negative internal entries are used to represent errnos.  Node pointers
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+ * are also tagged as internal entries in some situations.
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+ *
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+ * Context: Any context.
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+ * Return: An XArray internal entry corresponding to this value.
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+ */
143
+static inline void *xa_mk_internal(unsigned long v)
144
+{
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+	return (void *)((v << 2) | 2);
146
+}
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+
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+/*
149
+ * xa_to_internal() - Extract the value from an internal entry.
150
+ * @entry: XArray entry.
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+ *
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+ * Context: Any context.
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+ * Return: The value which was stored in the internal entry.
154
+ */
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+static inline unsigned long xa_to_internal(const void *entry)
156
+{
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+	return (unsigned long)entry >> 2;
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+}
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+
160
+/*
161
+ * xa_is_internal() - Is the entry an internal entry?
162
+ * @entry: XArray entry.
163
+ *
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+ * Context: Any context.
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+ * Return: %true if the entry is an internal entry.
166
+ */
167
+static inline bool xa_is_internal(const void *entry)
168
+{
169
+	return ((unsigned long)entry & 3) == 2;
170
+}
171
+
172
+#define XA_ZERO_ENTRY		xa_mk_internal(257)
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+
174
+/**
175
+ * xa_is_zero() - Is the entry a zero entry?
176
+ * @entry: Entry retrieved from the XArray
177
+ *
178
+ * The normal API will return NULL as the contents of a slot containing
179
+ * a zero entry.  You can only see zero entries by using the advanced API.
180
+ *
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+ * Return: %true if the entry is a zero entry.
182
+ */
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+static inline bool xa_is_zero(const void *entry)
184
+{
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+	return unlikely(entry == XA_ZERO_ENTRY);
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+}
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+
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+/**
189
+ * xa_is_err() - Report whether an XArray operation returned an error
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+ * @entry: Result from calling an XArray function
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+ *
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+ * If an XArray operation cannot complete an operation, it will return
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+ * a special value indicating an error.  This function tells you
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+ * whether an error occurred; xa_err() tells you which error occurred.
195
+ *
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+ * Context: Any context.
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+ * Return: %true if the entry indicates an error.
198
+ */
199
+static inline bool xa_is_err(const void *entry)
200
+{
201
+	return unlikely(xa_is_internal(entry) &&
202
+			entry >= xa_mk_internal(-MAX_ERRNO));
203
+}
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+
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+/**
206
+ * xa_err() - Turn an XArray result into an errno.
207
+ * @entry: Result from calling an XArray function.
208
+ *
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+ * If an XArray operation cannot complete an operation, it will return
210
+ * a special pointer value which encodes an errno.  This function extracts
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+ * the errno from the pointer value, or returns 0 if the pointer does not
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+ * represent an errno.
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+ *
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+ * Context: Any context.
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+ * Return: A negative errno or 0.
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+ */
217
+static inline int xa_err(void *entry)
218
+{
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+	/* xa_to_internal() would not do sign extension. */
220
+	if (xa_is_err(entry))
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+		return (long)entry >> 2;
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+	return 0;
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+}
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+
225
+/**
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+ * struct xa_limit - Represents a range of IDs.
227
+ * @min: The lowest ID to allocate (inclusive).
228
+ * @max: The maximum ID to allocate (inclusive).
229
+ *
230
+ * This structure is used either directly or via the XA_LIMIT() macro
231
+ * to communicate the range of IDs that are valid for allocation.
232
+ * Two common ranges are predefined for you:
233
+ * * xa_limit_32b	- [0 - UINT_MAX]
234
+ * * xa_limit_31b	- [0 - INT_MAX]
235
+ */
236
+struct xa_limit {
237
+	u32 max;
238
+	u32 min;
239
+};
240
+
241
+#define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
242
+
243
+#define xa_limit_32b	XA_LIMIT(0, UINT_MAX)
244
+#define xa_limit_31b	XA_LIMIT(0, INT_MAX)
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+
246
+typedef unsigned __bitwise xa_mark_t;
247
+#define XA_MARK_0		((__force xa_mark_t)0U)
248
+#define XA_MARK_1		((__force xa_mark_t)1U)
249
+#define XA_MARK_2		((__force xa_mark_t)2U)
250
+#define XA_PRESENT		((__force xa_mark_t)8U)
251
+#define XA_MARK_MAX		XA_MARK_2
252
+#define XA_FREE_MARK		XA_MARK_0
253
+
254
+enum xa_lock_type {
255
+	XA_LOCK_IRQ = 1,
256
+	XA_LOCK_BH = 2,
257
+};
258
+
259
+/*
260
+ * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
261
+ * and we remain compatible with that.
262
+ */
263
+#define XA_FLAGS_LOCK_IRQ	((__force gfp_t)XA_LOCK_IRQ)
264
+#define XA_FLAGS_LOCK_BH	((__force gfp_t)XA_LOCK_BH)
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+#define XA_FLAGS_TRACK_FREE	((__force gfp_t)4U)
266
+#define XA_FLAGS_ZERO_BUSY	((__force gfp_t)8U)
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+#define XA_FLAGS_ALLOC_WRAPPED	((__force gfp_t)16U)
268
+#define XA_FLAGS_ACCOUNT	((__force gfp_t)32U)
269
+#define XA_FLAGS_MARK(mark)	((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
270
+						(__force unsigned)(mark)))
271
+
272
+/* ALLOC is for a normal 0-based alloc.  ALLOC1 is for an 1-based alloc */
273
+#define XA_FLAGS_ALLOC	(XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
274
+#define XA_FLAGS_ALLOC1	(XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
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+
276
+/**
277
+ * struct xarray - The anchor of the XArray.
278
+ * @xa_lock: Lock that protects the contents of the XArray.
279
+ *
280
+ * To use the xarray, define it statically or embed it in your data structure.
281
+ * It is a very small data structure, so it does not usually make sense to
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+ * allocate it separately and keep a pointer to it in your data structure.
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+ *
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+ * You may use the xa_lock to protect your own data structures as well.
285
+ */
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+/*
287
+ * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
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+ * If the only non-NULL entry in the array is at index 0, @xa_head is that
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+ * entry.  If any other entry in the array is non-NULL, @xa_head points
290
+ * to an @xa_node.
291
+ */
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+struct xarray {
293
+	spinlock_t	xa_lock;
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+/* private: The rest of the data structure is not to be used directly. */
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+	gfp_t		xa_flags;
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+	void __rcu *	xa_head;
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+};
298
+
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+#define XARRAY_INIT(name, flags) {				\
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+	.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),		\
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+	.xa_flags = flags,					\
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+	.xa_head = NULL,					\
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+}
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+
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+/**
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+ * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
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+ * @name: A string that names your XArray.
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+ * @flags: XA_FLAG values.
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+ *
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+ * This is intended for file scope definitions of XArrays.  It declares
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+ * and initialises an empty XArray with the chosen name and flags.  It is
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+ * equivalent to calling xa_init_flags() on the array, but it does the
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+ * initialisation at compiletime instead of runtime.
314
+ */
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+#define DEFINE_XARRAY_FLAGS(name, flags)				\
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+	struct xarray name = XARRAY_INIT(name, flags)
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+
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+/**
319
+ * DEFINE_XARRAY() - Define an XArray.
320
+ * @name: A string that names your XArray.
321
+ *
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+ * This is intended for file scope definitions of XArrays.  It declares
323
+ * and initialises an empty XArray with the chosen name.  It is equivalent
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+ * to calling xa_init() on the array, but it does the initialisation at
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+ * compiletime instead of runtime.
326
+ */
327
+#define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
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+
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+/**
330
+ * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
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+ * @name: A string that names your XArray.
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+ *
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+ * This is intended for file scope definitions of allocating XArrays.
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+ * See also DEFINE_XARRAY().
335
+ */
336
+#define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
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+
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+/**
339
+ * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
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+ * @name: A string that names your XArray.
341
+ *
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+ * This is intended for file scope definitions of allocating XArrays.
343
+ * See also DEFINE_XARRAY().
344
+ */
345
+#define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
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+
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+void *xa_load(struct xarray *, unsigned long index);
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+void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
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+void *xa_erase(struct xarray *, unsigned long index);
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+void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
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+			void *entry, gfp_t);
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+bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
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+void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
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+void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
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+void *xa_find(struct xarray *xa, unsigned long *index,
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+		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
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+void *xa_find_after(struct xarray *xa, unsigned long *index,
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+		unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
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+unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
360
+		unsigned long max, unsigned int n, xa_mark_t);
361
+void xa_destroy(struct xarray *);
362
+
363
+/**
364
+ * xa_init_flags() - Initialise an empty XArray with flags.
365
+ * @xa: XArray.
366
+ * @flags: XA_FLAG values.
367
+ *
368
+ * If you need to initialise an XArray with special flags (eg you need
369
+ * to take the lock from interrupt context), use this function instead
370
+ * of xa_init().
371
+ *
372
+ * Context: Any context.
373
+ */
374
+static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
375
+{
376
+	spin_lock_init(&xa->xa_lock);
377
+	xa->xa_flags = flags;
378
+	xa->xa_head = NULL;
379
+}
380
+
381
+/**
382
+ * xa_init() - Initialise an empty XArray.
383
+ * @xa: XArray.
384
+ *
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+ * An empty XArray is full of NULL entries.
386
+ *
387
+ * Context: Any context.
388
+ */
389
+static inline void xa_init(struct xarray *xa)
390
+{
391
+	xa_init_flags(xa, 0);
392
+}
393
+
394
+/**
395
+ * xa_empty() - Determine if an array has any present entries.
396
+ * @xa: XArray.
397
+ *
398
+ * Context: Any context.
399
+ * Return: %true if the array contains only NULL pointers.
400
+ */
401
+static inline bool xa_empty(const struct xarray *xa)
402
+{
403
+	return xa->xa_head == NULL;
404
+}
405
+
406
+/**
407
+ * xa_marked() - Inquire whether any entry in this array has a mark set
408
+ * @xa: Array
409
+ * @mark: Mark value
410
+ *
411
+ * Context: Any context.
412
+ * Return: %true if any entry has this mark set.
413
+ */
414
+static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
415
+{
416
+	return xa->xa_flags & XA_FLAGS_MARK(mark);
417
+}
418
+
419
+/**
420
+ * xa_for_each_range() - Iterate over a portion of an XArray.
421
+ * @xa: XArray.
422
+ * @index: Index of @entry.
423
+ * @entry: Entry retrieved from array.
424
+ * @start: First index to retrieve from array.
425
+ * @last: Last index to retrieve from array.
426
+ *
427
+ * During the iteration, @entry will have the value of the entry stored
428
+ * in @xa at @index.  You may modify @index during the iteration if you
429
+ * want to skip or reprocess indices.  It is safe to modify the array
430
+ * during the iteration.  At the end of the iteration, @entry will be set
431
+ * to NULL and @index will have a value less than or equal to max.
432
+ *
433
+ * xa_for_each_range() is O(n.log(n)) while xas_for_each() is O(n).  You have
434
+ * to handle your own locking with xas_for_each(), and if you have to unlock
435
+ * after each iteration, it will also end up being O(n.log(n)).
436
+ * xa_for_each_range() will spin if it hits a retry entry; if you intend to
437
+ * see retry entries, you should use the xas_for_each() iterator instead.
438
+ * The xas_for_each() iterator will expand into more inline code than
439
+ * xa_for_each_range().
440
+ *
441
+ * Context: Any context.  Takes and releases the RCU lock.
442
+ */
443
+#define xa_for_each_range(xa, index, entry, start, last)		\
444
+	for (index = start,						\
445
+	     entry = xa_find(xa, &index, last, XA_PRESENT);		\
446
+	     entry;							\
447
+	     entry = xa_find_after(xa, &index, last, XA_PRESENT))
448
+
449
+/**
450
+ * xa_for_each_start() - Iterate over a portion of an XArray.
451
+ * @xa: XArray.
452
+ * @index: Index of @entry.
453
+ * @entry: Entry retrieved from array.
454
+ * @start: First index to retrieve from array.
455
+ *
456
+ * During the iteration, @entry will have the value of the entry stored
457
+ * in @xa at @index.  You may modify @index during the iteration if you
458
+ * want to skip or reprocess indices.  It is safe to modify the array
459
+ * during the iteration.  At the end of the iteration, @entry will be set
460
+ * to NULL and @index will have a value less than or equal to max.
461
+ *
462
+ * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n).  You have
463
+ * to handle your own locking with xas_for_each(), and if you have to unlock
464
+ * after each iteration, it will also end up being O(n.log(n)).
465
+ * xa_for_each_start() will spin if it hits a retry entry; if you intend to
466
+ * see retry entries, you should use the xas_for_each() iterator instead.
467
+ * The xas_for_each() iterator will expand into more inline code than
468
+ * xa_for_each_start().
469
+ *
470
+ * Context: Any context.  Takes and releases the RCU lock.
471
+ */
472
+#define xa_for_each_start(xa, index, entry, start) \
473
+	xa_for_each_range(xa, index, entry, start, ULONG_MAX)
474
+
475
+/**
476
+ * xa_for_each() - Iterate over present entries in an XArray.
477
+ * @xa: XArray.
478
+ * @index: Index of @entry.
479
+ * @entry: Entry retrieved from array.
480
+ *
481
+ * During the iteration, @entry will have the value of the entry stored
482
+ * in @xa at @index.  You may modify @index during the iteration if you want
483
+ * to skip or reprocess indices.  It is safe to modify the array during the
484
+ * iteration.  At the end of the iteration, @entry will be set to NULL and
485
+ * @index will have a value less than or equal to max.
486
+ *
487
+ * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n).  You have
488
+ * to handle your own locking with xas_for_each(), and if you have to unlock
489
+ * after each iteration, it will also end up being O(n.log(n)).  xa_for_each()
490
+ * will spin if it hits a retry entry; if you intend to see retry entries,
491
+ * you should use the xas_for_each() iterator instead.  The xas_for_each()
492
+ * iterator will expand into more inline code than xa_for_each().
493
+ *
494
+ * Context: Any context.  Takes and releases the RCU lock.
495
+ */
496
+#define xa_for_each(xa, index, entry) \
497
+	xa_for_each_start(xa, index, entry, 0)
498
+
499
+/**
500
+ * xa_for_each_marked() - Iterate over marked entries in an XArray.
501
+ * @xa: XArray.
502
+ * @index: Index of @entry.
503
+ * @entry: Entry retrieved from array.
504
+ * @filter: Selection criterion.
505
+ *
506
+ * During the iteration, @entry will have the value of the entry stored
507
+ * in @xa at @index.  The iteration will skip all entries in the array
508
+ * which do not match @filter.  You may modify @index during the iteration
509
+ * if you want to skip or reprocess indices.  It is safe to modify the array
510
+ * during the iteration.  At the end of the iteration, @entry will be set to
511
+ * NULL and @index will have a value less than or equal to max.
512
+ *
513
+ * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
514
+ * You have to handle your own locking with xas_for_each(), and if you have
515
+ * to unlock after each iteration, it will also end up being O(n.log(n)).
516
+ * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
517
+ * see retry entries, you should use the xas_for_each_marked() iterator
518
+ * instead.  The xas_for_each_marked() iterator will expand into more inline
519
+ * code than xa_for_each_marked().
520
+ *
521
+ * Context: Any context.  Takes and releases the RCU lock.
522
+ */
523
+#define xa_for_each_marked(xa, index, entry, filter) \
524
+	for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
525
+	     entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
11
526
 
12
527
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
13
528
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
..
..
@@ -20,5 +535,1289 @@
20
535
 				spin_lock_irqsave(&(xa)->xa_lock, flags)
21
536
 #define xa_unlock_irqrestore(xa, flags) \
22
537
 				spin_unlock_irqrestore(&(xa)->xa_lock, flags)
538
+#define xa_lock_nested(xa, subclass) \
539
+				spin_lock_nested(&(xa)->xa_lock, subclass)
540
+#define xa_lock_bh_nested(xa, subclass) \
541
+				spin_lock_bh_nested(&(xa)->xa_lock, subclass)
542
+#define xa_lock_irq_nested(xa, subclass) \
543
+				spin_lock_irq_nested(&(xa)->xa_lock, subclass)
544
+#define xa_lock_irqsave_nested(xa, flags, subclass) \
545
+		spin_lock_irqsave_nested(&(xa)->xa_lock, flags, subclass)
546
+
547
+/*
548
+ * Versions of the normal API which require the caller to hold the
549
+ * xa_lock.  If the GFP flags allow it, they will drop the lock to
550
+ * allocate memory, then reacquire it afterwards.  These functions
551
+ * may also re-enable interrupts if the XArray flags indicate the
552
+ * locking should be interrupt safe.
553
+ */
554
+void *__xa_erase(struct xarray *, unsigned long index);
555
+void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
556
+void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
557
+		void *entry, gfp_t);
558
+int __must_check __xa_insert(struct xarray *, unsigned long index,
559
+		void *entry, gfp_t);
560
+int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
561
+		struct xa_limit, gfp_t);
562
+int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
563
+		struct xa_limit, u32 *next, gfp_t);
564
+void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
565
+void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
566
+
567
+/**
568
+ * xa_store_bh() - Store this entry in the XArray.
569
+ * @xa: XArray.
570
+ * @index: Index into array.
571
+ * @entry: New entry.
572
+ * @gfp: Memory allocation flags.
573
+ *
574
+ * This function is like calling xa_store() except it disables softirqs
575
+ * while holding the array lock.
576
+ *
577
+ * Context: Any context.  Takes and releases the xa_lock while
578
+ * disabling softirqs.
579
+ * Return: The old entry at this index or xa_err() if an error happened.
580
+ */
581
+static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
582
+		void *entry, gfp_t gfp)
583
+{
584
+	void *curr;
585
+
586
+	xa_lock_bh(xa);
587
+	curr = __xa_store(xa, index, entry, gfp);
588
+	xa_unlock_bh(xa);
589
+
590
+	return curr;
591
+}
592
+
593
+/**
594
+ * xa_store_irq() - Store this entry in the XArray.
595
+ * @xa: XArray.
596
+ * @index: Index into array.
597
+ * @entry: New entry.
598
+ * @gfp: Memory allocation flags.
599
+ *
600
+ * This function is like calling xa_store() except it disables interrupts
601
+ * while holding the array lock.
602
+ *
603
+ * Context: Process context.  Takes and releases the xa_lock while
604
+ * disabling interrupts.
605
+ * Return: The old entry at this index or xa_err() if an error happened.
606
+ */
607
+static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
608
+		void *entry, gfp_t gfp)
609
+{
610
+	void *curr;
611
+
612
+	xa_lock_irq(xa);
613
+	curr = __xa_store(xa, index, entry, gfp);
614
+	xa_unlock_irq(xa);
615
+
616
+	return curr;
617
+}
618
+
619
+/**
620
+ * xa_erase_bh() - Erase this entry from the XArray.
621
+ * @xa: XArray.
622
+ * @index: Index of entry.
623
+ *
624
+ * After this function returns, loading from @index will return %NULL.
625
+ * If the index is part of a multi-index entry, all indices will be erased
626
+ * and none of the entries will be part of a multi-index entry.
627
+ *
628
+ * Context: Any context.  Takes and releases the xa_lock while
629
+ * disabling softirqs.
630
+ * Return: The entry which used to be at this index.
631
+ */
632
+static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
633
+{
634
+	void *entry;
635
+
636
+	xa_lock_bh(xa);
637
+	entry = __xa_erase(xa, index);
638
+	xa_unlock_bh(xa);
639
+
640
+	return entry;
641
+}
642
+
643
+/**
644
+ * xa_erase_irq() - Erase this entry from the XArray.
645
+ * @xa: XArray.
646
+ * @index: Index of entry.
647
+ *
648
+ * After this function returns, loading from @index will return %NULL.
649
+ * If the index is part of a multi-index entry, all indices will be erased
650
+ * and none of the entries will be part of a multi-index entry.
651
+ *
652
+ * Context: Process context.  Takes and releases the xa_lock while
653
+ * disabling interrupts.
654
+ * Return: The entry which used to be at this index.
655
+ */
656
+static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
657
+{
658
+	void *entry;
659
+
660
+	xa_lock_irq(xa);
661
+	entry = __xa_erase(xa, index);
662
+	xa_unlock_irq(xa);
663
+
664
+	return entry;
665
+}
666
+
667
+/**
668
+ * xa_cmpxchg() - Conditionally replace an entry in the XArray.
669
+ * @xa: XArray.
670
+ * @index: Index into array.
671
+ * @old: Old value to test against.
672
+ * @entry: New value to place in array.
673
+ * @gfp: Memory allocation flags.
674
+ *
675
+ * If the entry at @index is the same as @old, replace it with @entry.
676
+ * If the return value is equal to @old, then the exchange was successful.
677
+ *
678
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep
679
+ * if the @gfp flags permit.
680
+ * Return: The old value at this index or xa_err() if an error happened.
681
+ */
682
+static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
683
+			void *old, void *entry, gfp_t gfp)
684
+{
685
+	void *curr;
686
+
687
+	xa_lock(xa);
688
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
689
+	xa_unlock(xa);
690
+
691
+	return curr;
692
+}
693
+
694
+/**
695
+ * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
696
+ * @xa: XArray.
697
+ * @index: Index into array.
698
+ * @old: Old value to test against.
699
+ * @entry: New value to place in array.
700
+ * @gfp: Memory allocation flags.
701
+ *
702
+ * This function is like calling xa_cmpxchg() except it disables softirqs
703
+ * while holding the array lock.
704
+ *
705
+ * Context: Any context.  Takes and releases the xa_lock while
706
+ * disabling softirqs.  May sleep if the @gfp flags permit.
707
+ * Return: The old value at this index or xa_err() if an error happened.
708
+ */
709
+static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
710
+			void *old, void *entry, gfp_t gfp)
711
+{
712
+	void *curr;
713
+
714
+	xa_lock_bh(xa);
715
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
716
+	xa_unlock_bh(xa);
717
+
718
+	return curr;
719
+}
720
+
721
+/**
722
+ * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
723
+ * @xa: XArray.
724
+ * @index: Index into array.
725
+ * @old: Old value to test against.
726
+ * @entry: New value to place in array.
727
+ * @gfp: Memory allocation flags.
728
+ *
729
+ * This function is like calling xa_cmpxchg() except it disables interrupts
730
+ * while holding the array lock.
731
+ *
732
+ * Context: Process context.  Takes and releases the xa_lock while
733
+ * disabling interrupts.  May sleep if the @gfp flags permit.
734
+ * Return: The old value at this index or xa_err() if an error happened.
735
+ */
736
+static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
737
+			void *old, void *entry, gfp_t gfp)
738
+{
739
+	void *curr;
740
+
741
+	xa_lock_irq(xa);
742
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
743
+	xa_unlock_irq(xa);
744
+
745
+	return curr;
746
+}
747
+
748
+/**
749
+ * xa_insert() - Store this entry in the XArray unless another entry is
750
+ *			already present.
751
+ * @xa: XArray.
752
+ * @index: Index into array.
753
+ * @entry: New entry.
754
+ * @gfp: Memory allocation flags.
755
+ *
756
+ * Inserting a NULL entry will store a reserved entry (like xa_reserve())
757
+ * if no entry is present.  Inserting will fail if a reserved entry is
758
+ * present, even though loading from this index will return NULL.
759
+ *
760
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep if
761
+ * the @gfp flags permit.
762
+ * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
763
+ * -ENOMEM if memory could not be allocated.
764
+ */
765
+static inline int __must_check xa_insert(struct xarray *xa,
766
+		unsigned long index, void *entry, gfp_t gfp)
767
+{
768
+	int err;
769
+
770
+	xa_lock(xa);
771
+	err = __xa_insert(xa, index, entry, gfp);
772
+	xa_unlock(xa);
773
+
774
+	return err;
775
+}
776
+
777
+/**
778
+ * xa_insert_bh() - Store this entry in the XArray unless another entry is
779
+ *			already present.
780
+ * @xa: XArray.
781
+ * @index: Index into array.
782
+ * @entry: New entry.
783
+ * @gfp: Memory allocation flags.
784
+ *
785
+ * Inserting a NULL entry will store a reserved entry (like xa_reserve())
786
+ * if no entry is present.  Inserting will fail if a reserved entry is
787
+ * present, even though loading from this index will return NULL.
788
+ *
789
+ * Context: Any context.  Takes and releases the xa_lock while
790
+ * disabling softirqs.  May sleep if the @gfp flags permit.
791
+ * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
792
+ * -ENOMEM if memory could not be allocated.
793
+ */
794
+static inline int __must_check xa_insert_bh(struct xarray *xa,
795
+		unsigned long index, void *entry, gfp_t gfp)
796
+{
797
+	int err;
798
+
799
+	xa_lock_bh(xa);
800
+	err = __xa_insert(xa, index, entry, gfp);
801
+	xa_unlock_bh(xa);
802
+
803
+	return err;
804
+}
805
+
806
+/**
807
+ * xa_insert_irq() - Store this entry in the XArray unless another entry is
808
+ *			already present.
809
+ * @xa: XArray.
810
+ * @index: Index into array.
811
+ * @entry: New entry.
812
+ * @gfp: Memory allocation flags.
813
+ *
814
+ * Inserting a NULL entry will store a reserved entry (like xa_reserve())
815
+ * if no entry is present.  Inserting will fail if a reserved entry is
816
+ * present, even though loading from this index will return NULL.
817
+ *
818
+ * Context: Process context.  Takes and releases the xa_lock while
819
+ * disabling interrupts.  May sleep if the @gfp flags permit.
820
+ * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
821
+ * -ENOMEM if memory could not be allocated.
822
+ */
823
+static inline int __must_check xa_insert_irq(struct xarray *xa,
824
+		unsigned long index, void *entry, gfp_t gfp)
825
+{
826
+	int err;
827
+
828
+	xa_lock_irq(xa);
829
+	err = __xa_insert(xa, index, entry, gfp);
830
+	xa_unlock_irq(xa);
831
+
832
+	return err;
833
+}
834
+
835
+/**
836
+ * xa_alloc() - Find somewhere to store this entry in the XArray.
837
+ * @xa: XArray.
838
+ * @id: Pointer to ID.
839
+ * @entry: New entry.
840
+ * @limit: Range of ID to allocate.
841
+ * @gfp: Memory allocation flags.
842
+ *
843
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
844
+ * stores the index into the @id pointer, then stores the entry at
845
+ * that index.  A concurrent lookup will not see an uninitialised @id.
846
+ *
847
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep if
848
+ * the @gfp flags permit.
849
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
850
+ * -EBUSY if there are no free entries in @limit.
851
+ */
852
+static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
853
+		void *entry, struct xa_limit limit, gfp_t gfp)
854
+{
855
+	int err;
856
+
857
+	xa_lock(xa);
858
+	err = __xa_alloc(xa, id, entry, limit, gfp);
859
+	xa_unlock(xa);
860
+
861
+	return err;
862
+}
863
+
864
+/**
865
+ * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
866
+ * @xa: XArray.
867
+ * @id: Pointer to ID.
868
+ * @entry: New entry.
869
+ * @limit: Range of ID to allocate.
870
+ * @gfp: Memory allocation flags.
871
+ *
872
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
873
+ * stores the index into the @id pointer, then stores the entry at
874
+ * that index.  A concurrent lookup will not see an uninitialised @id.
875
+ *
876
+ * Context: Any context.  Takes and releases the xa_lock while
877
+ * disabling softirqs.  May sleep if the @gfp flags permit.
878
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
879
+ * -EBUSY if there are no free entries in @limit.
880
+ */
881
+static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
882
+		void *entry, struct xa_limit limit, gfp_t gfp)
883
+{
884
+	int err;
885
+
886
+	xa_lock_bh(xa);
887
+	err = __xa_alloc(xa, id, entry, limit, gfp);
888
+	xa_unlock_bh(xa);
889
+
890
+	return err;
891
+}
892
+
893
+/**
894
+ * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
895
+ * @xa: XArray.
896
+ * @id: Pointer to ID.
897
+ * @entry: New entry.
898
+ * @limit: Range of ID to allocate.
899
+ * @gfp: Memory allocation flags.
900
+ *
901
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
902
+ * stores the index into the @id pointer, then stores the entry at
903
+ * that index.  A concurrent lookup will not see an uninitialised @id.
904
+ *
905
+ * Context: Process context.  Takes and releases the xa_lock while
906
+ * disabling interrupts.  May sleep if the @gfp flags permit.
907
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
908
+ * -EBUSY if there are no free entries in @limit.
909
+ */
910
+static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
911
+		void *entry, struct xa_limit limit, gfp_t gfp)
912
+{
913
+	int err;
914
+
915
+	xa_lock_irq(xa);
916
+	err = __xa_alloc(xa, id, entry, limit, gfp);
917
+	xa_unlock_irq(xa);
918
+
919
+	return err;
920
+}
921
+
922
+/**
923
+ * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
924
+ * @xa: XArray.
925
+ * @id: Pointer to ID.
926
+ * @entry: New entry.
927
+ * @limit: Range of allocated ID.
928
+ * @next: Pointer to next ID to allocate.
929
+ * @gfp: Memory allocation flags.
930
+ *
931
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
932
+ * stores the index into the @id pointer, then stores the entry at
933
+ * that index.  A concurrent lookup will not see an uninitialised @id.
934
+ * The search for an empty entry will start at @next and will wrap
935
+ * around if necessary.
936
+ *
937
+ * Context: Any context.  Takes and releases the xa_lock.  May sleep if
938
+ * the @gfp flags permit.
939
+ * Return: 0 if the allocation succeeded without wrapping.  1 if the
940
+ * allocation succeeded after wrapping, -ENOMEM if memory could not be
941
+ * allocated or -EBUSY if there are no free entries in @limit.
942
+ */
943
+static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
944
+		struct xa_limit limit, u32 *next, gfp_t gfp)
945
+{
946
+	int err;
947
+
948
+	xa_lock(xa);
949
+	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
950
+	xa_unlock(xa);
951
+
952
+	return err;
953
+}
954
+
955
+/**
956
+ * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
957
+ * @xa: XArray.
958
+ * @id: Pointer to ID.
959
+ * @entry: New entry.
960
+ * @limit: Range of allocated ID.
961
+ * @next: Pointer to next ID to allocate.
962
+ * @gfp: Memory allocation flags.
963
+ *
964
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
965
+ * stores the index into the @id pointer, then stores the entry at
966
+ * that index.  A concurrent lookup will not see an uninitialised @id.
967
+ * The search for an empty entry will start at @next and will wrap
968
+ * around if necessary.
969
+ *
970
+ * Context: Any context.  Takes and releases the xa_lock while
971
+ * disabling softirqs.  May sleep if the @gfp flags permit.
972
+ * Return: 0 if the allocation succeeded without wrapping.  1 if the
973
+ * allocation succeeded after wrapping, -ENOMEM if memory could not be
974
+ * allocated or -EBUSY if there are no free entries in @limit.
975
+ */
976
+static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
977
+		struct xa_limit limit, u32 *next, gfp_t gfp)
978
+{
979
+	int err;
980
+
981
+	xa_lock_bh(xa);
982
+	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
983
+	xa_unlock_bh(xa);
984
+
985
+	return err;
986
+}
987
+
988
+/**
989
+ * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
990
+ * @xa: XArray.
991
+ * @id: Pointer to ID.
992
+ * @entry: New entry.
993
+ * @limit: Range of allocated ID.
994
+ * @next: Pointer to next ID to allocate.
995
+ * @gfp: Memory allocation flags.
996
+ *
997
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
998
+ * stores the index into the @id pointer, then stores the entry at
999
+ * that index.  A concurrent lookup will not see an uninitialised @id.
1000
+ * The search for an empty entry will start at @next and will wrap
1001
+ * around if necessary.
1002
+ *
1003
+ * Context: Process context.  Takes and releases the xa_lock while
1004
+ * disabling interrupts.  May sleep if the @gfp flags permit.
1005
+ * Return: 0 if the allocation succeeded without wrapping.  1 if the
1006
+ * allocation succeeded after wrapping, -ENOMEM if memory could not be
1007
+ * allocated or -EBUSY if there are no free entries in @limit.
1008
+ */
1009
+static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
1010
+		struct xa_limit limit, u32 *next, gfp_t gfp)
1011
+{
1012
+	int err;
1013
+
1014
+	xa_lock_irq(xa);
1015
+	err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
1016
+	xa_unlock_irq(xa);
1017
+
1018
+	return err;
1019
+}
1020
+
1021
+/**
1022
+ * xa_reserve() - Reserve this index in the XArray.
1023
+ * @xa: XArray.
1024
+ * @index: Index into array.
1025
+ * @gfp: Memory allocation flags.
1026
+ *
1027
+ * Ensures there is somewhere to store an entry at @index in the array.
1028
+ * If there is already something stored at @index, this function does
1029
+ * nothing.  If there was nothing there, the entry is marked as reserved.
1030
+ * Loading from a reserved entry returns a %NULL pointer.
1031
+ *
1032
+ * If you do not use the entry that you have reserved, call xa_release()
1033
+ * or xa_erase() to free any unnecessary memory.
1034
+ *
1035
+ * Context: Any context.  Takes and releases the xa_lock.
1036
+ * May sleep if the @gfp flags permit.
1037
+ * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1038
+ */
1039
+static inline __must_check
1040
+int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1041
+{
1042
+	return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1043
+}
1044
+
1045
+/**
1046
+ * xa_reserve_bh() - Reserve this index in the XArray.
1047
+ * @xa: XArray.
1048
+ * @index: Index into array.
1049
+ * @gfp: Memory allocation flags.
1050
+ *
1051
+ * A softirq-disabling version of xa_reserve().
1052
+ *
1053
+ * Context: Any context.  Takes and releases the xa_lock while
1054
+ * disabling softirqs.
1055
+ * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1056
+ */
1057
+static inline __must_check
1058
+int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
1059
+{
1060
+	return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1061
+}
1062
+
1063
+/**
1064
+ * xa_reserve_irq() - Reserve this index in the XArray.
1065
+ * @xa: XArray.
1066
+ * @index: Index into array.
1067
+ * @gfp: Memory allocation flags.
1068
+ *
1069
+ * An interrupt-disabling version of xa_reserve().
1070
+ *
1071
+ * Context: Process context.  Takes and releases the xa_lock while
1072
+ * disabling interrupts.
1073
+ * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1074
+ */
1075
+static inline __must_check
1076
+int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
1077
+{
1078
+	return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
1079
+}
1080
+
1081
+/**
1082
+ * xa_release() - Release a reserved entry.
1083
+ * @xa: XArray.
1084
+ * @index: Index of entry.
1085
+ *
1086
+ * After calling xa_reserve(), you can call this function to release the
1087
+ * reservation.  If the entry at @index has been stored to, this function
1088
+ * will do nothing.
1089
+ */
1090
+static inline void xa_release(struct xarray *xa, unsigned long index)
1091
+{
1092
+	xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
1093
+}
1094
+
1095
+/* Everything below here is the Advanced API.  Proceed with caution. */
1096
+
1097
+/*
1098
+ * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
1099
+ * the best chunk size requires some tradeoffs.  A power of two recommends
1100
+ * itself so that we can walk the tree based purely on shifts and masks.
1101
+ * Generally, the larger the better; as the number of slots per level of the
1102
+ * tree increases, the less tall the tree needs to be.  But that needs to be
1103
+ * balanced against the memory consumption of each node.  On a 64-bit system,
1104
+ * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
1105
+ * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
1106
+ */
1107
+#ifndef XA_CHUNK_SHIFT
1108
+#define XA_CHUNK_SHIFT		(CONFIG_BASE_SMALL ? 4 : 6)
1109
+#endif
1110
+#define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
1111
+#define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
1112
+#define XA_MAX_MARKS		3
1113
+#define XA_MARK_LONGS		DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
1114
+
1115
+/*
1116
+ * @count is the count of every non-NULL element in the ->slots array
1117
+ * whether that is a value entry, a retry entry, a user pointer,
1118
+ * a sibling entry or a pointer to the next level of the tree.
1119
+ * @nr_values is the count of every element in ->slots which is
1120
+ * either a value entry or a sibling of a value entry.
1121
+ */
1122
+struct xa_node {
1123
+	unsigned char	shift;		/* Bits remaining in each slot */
1124
+	unsigned char	offset;		/* Slot offset in parent */
1125
+	unsigned char	count;		/* Total entry count */
1126
+	unsigned char	nr_values;	/* Value entry count */
1127
+	struct xa_node __rcu *parent;	/* NULL at top of tree */
1128
+	struct xarray	*array;		/* The array we belong to */
1129
+	union {
1130
+		struct list_head private_list;	/* For tree user */
1131
+		struct rcu_head	rcu_head;	/* Used when freeing node */
1132
+	};
1133
+	void __rcu	*slots[XA_CHUNK_SIZE];
1134
+	union {
1135
+		unsigned long	tags[XA_MAX_MARKS][XA_MARK_LONGS];
1136
+		unsigned long	marks[XA_MAX_MARKS][XA_MARK_LONGS];
1137
+	};
1138
+};
1139
+
1140
+void xa_dump(const struct xarray *);
1141
+void xa_dump_node(const struct xa_node *);
1142
+
1143
+#ifdef XA_DEBUG
1144
+#define XA_BUG_ON(xa, x) do {					\
1145
+		if (x) {					\
1146
+			xa_dump(xa);				\
1147
+			BUG();					\
1148
+		}						\
1149
+	} while (0)
1150
+#define XA_NODE_BUG_ON(node, x) do {				\
1151
+		if (x) {					\
1152
+			if (node) xa_dump_node(node);		\
1153
+			BUG();					\
1154
+		}						\
1155
+	} while (0)
1156
+#else
1157
+#define XA_BUG_ON(xa, x)	do { } while (0)
1158
+#define XA_NODE_BUG_ON(node, x)	do { } while (0)
1159
+#endif
1160
+
1161
+/* Private */
1162
+static inline void *xa_head(const struct xarray *xa)
1163
+{
1164
+	return rcu_dereference_check(xa->xa_head,
1165
+						lockdep_is_held(&xa->xa_lock));
1166
+}
1167
+
1168
+/* Private */
1169
+static inline void *xa_head_locked(const struct xarray *xa)
1170
+{
1171
+	return rcu_dereference_protected(xa->xa_head,
1172
+						lockdep_is_held(&xa->xa_lock));
1173
+}
1174
+
1175
+/* Private */
1176
+static inline void *xa_entry(const struct xarray *xa,
1177
+				const struct xa_node *node, unsigned int offset)
1178
+{
1179
+	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1180
+	return rcu_dereference_check(node->slots[offset],
1181
+						lockdep_is_held(&xa->xa_lock));
1182
+}
1183
+
1184
+/* Private */
1185
+static inline void *xa_entry_locked(const struct xarray *xa,
1186
+				const struct xa_node *node, unsigned int offset)
1187
+{
1188
+	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
1189
+	return rcu_dereference_protected(node->slots[offset],
1190
+						lockdep_is_held(&xa->xa_lock));
1191
+}
1192
+
1193
+/* Private */
1194
+static inline struct xa_node *xa_parent(const struct xarray *xa,
1195
+					const struct xa_node *node)
1196
+{
1197
+	return rcu_dereference_check(node->parent,
1198
+						lockdep_is_held(&xa->xa_lock));
1199
+}
1200
+
1201
+/* Private */
1202
+static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
1203
+					const struct xa_node *node)
1204
+{
1205
+	return rcu_dereference_protected(node->parent,
1206
+						lockdep_is_held(&xa->xa_lock));
1207
+}
1208
+
1209
+/* Private */
1210
+static inline void *xa_mk_node(const struct xa_node *node)
1211
+{
1212
+	return (void *)((unsigned long)node | 2);
1213
+}
1214
+
1215
+/* Private */
1216
+static inline struct xa_node *xa_to_node(const void *entry)
1217
+{
1218
+	return (struct xa_node *)((unsigned long)entry - 2);
1219
+}
1220
+
1221
+/* Private */
1222
+static inline bool xa_is_node(const void *entry)
1223
+{
1224
+	return xa_is_internal(entry) && (unsigned long)entry > 4096;
1225
+}
1226
+
1227
+/* Private */
1228
+static inline void *xa_mk_sibling(unsigned int offset)
1229
+{
1230
+	return xa_mk_internal(offset);
1231
+}
1232
+
1233
+/* Private */
1234
+static inline unsigned long xa_to_sibling(const void *entry)
1235
+{
1236
+	return xa_to_internal(entry);
1237
+}
1238
+
1239
+/**
1240
+ * xa_is_sibling() - Is the entry a sibling entry?
1241
+ * @entry: Entry retrieved from the XArray
1242
+ *
1243
+ * Return: %true if the entry is a sibling entry.
1244
+ */
1245
+static inline bool xa_is_sibling(const void *entry)
1246
+{
1247
+	return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
1248
+		(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
1249
+}
1250
+
1251
+#define XA_RETRY_ENTRY		xa_mk_internal(256)
1252
+
1253
+/**
1254
+ * xa_is_retry() - Is the entry a retry entry?
1255
+ * @entry: Entry retrieved from the XArray
1256
+ *
1257
+ * Return: %true if the entry is a retry entry.
1258
+ */
1259
+static inline bool xa_is_retry(const void *entry)
1260
+{
1261
+	return unlikely(entry == XA_RETRY_ENTRY);
1262
+}
1263
+
1264
+/**
1265
+ * xa_is_advanced() - Is the entry only permitted for the advanced API?
1266
+ * @entry: Entry to be stored in the XArray.
1267
+ *
1268
+ * Return: %true if the entry cannot be stored by the normal API.
1269
+ */
1270
+static inline bool xa_is_advanced(const void *entry)
1271
+{
1272
+	return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
1273
+}
1274
+
1275
+/**
1276
+ * typedef xa_update_node_t - A callback function from the XArray.
1277
+ * @node: The node which is being processed
1278
+ *
1279
+ * This function is called every time the XArray updates the count of
1280
+ * present and value entries in a node.  It allows advanced users to
1281
+ * maintain the private_list in the node.
1282
+ *
1283
+ * Context: The xa_lock is held and interrupts may be disabled.
1284
+ *	    Implementations should not drop the xa_lock, nor re-enable
1285
+ *	    interrupts.
1286
+ */
1287
+typedef void (*xa_update_node_t)(struct xa_node *node);
1288
+
1289
+void xa_delete_node(struct xa_node *, xa_update_node_t);
1290
+
1291
+/*
1292
+ * The xa_state is opaque to its users.  It contains various different pieces
1293
+ * of state involved in the current operation on the XArray.  It should be
1294
+ * declared on the stack and passed between the various internal routines.
1295
+ * The various elements in it should not be accessed directly, but only
1296
+ * through the provided accessor functions.  The below documentation is for
1297
+ * the benefit of those working on the code, not for users of the XArray.
1298
+ *
1299
+ * @xa_node usually points to the xa_node containing the slot we're operating
1300
+ * on (and @xa_offset is the offset in the slots array).  If there is a
1301
+ * single entry in the array at index 0, there are no allocated xa_nodes to
1302
+ * point to, and so we store %NULL in @xa_node.  @xa_node is set to
1303
+ * the value %XAS_RESTART if the xa_state is not walked to the correct
1304
+ * position in the tree of nodes for this operation.  If an error occurs
1305
+ * during an operation, it is set to an %XAS_ERROR value.  If we run off the
1306
+ * end of the allocated nodes, it is set to %XAS_BOUNDS.
1307
+ */
1308
+struct xa_state {
1309
+	struct xarray *xa;
1310
+	unsigned long xa_index;
1311
+	unsigned char xa_shift;
1312
+	unsigned char xa_sibs;
1313
+	unsigned char xa_offset;
1314
+	unsigned char xa_pad;		/* Helps gcc generate better code */
1315
+	struct xa_node *xa_node;
1316
+	struct xa_node *xa_alloc;
1317
+	xa_update_node_t xa_update;
1318
+};
1319
+
1320
+/*
1321
+ * We encode errnos in the xas->xa_node.  If an error has happened, we need to
1322
+ * drop the lock to fix it, and once we've done so the xa_state is invalid.
1323
+ */
1324
+#define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
1325
+#define XAS_BOUNDS	((struct xa_node *)1UL)
1326
+#define XAS_RESTART	((struct xa_node *)3UL)
1327
+
1328
+#define __XA_STATE(array, index, shift, sibs)  {	\
1329
+	.xa = array,					\
1330
+	.xa_index = index,				\
1331
+	.xa_shift = shift,				\
1332
+	.xa_sibs = sibs,				\
1333
+	.xa_offset = 0,					\
1334
+	.xa_pad = 0,					\
1335
+	.xa_node = XAS_RESTART,				\
1336
+	.xa_alloc = NULL,				\
1337
+	.xa_update = NULL				\
1338
+}
1339
+
1340
+/**
1341
+ * XA_STATE() - Declare an XArray operation state.
1342
+ * @name: Name of this operation state (usually xas).
1343
+ * @array: Array to operate on.
1344
+ * @index: Initial index of interest.
1345
+ *
1346
+ * Declare and initialise an xa_state on the stack.
1347
+ */
1348
+#define XA_STATE(name, array, index)				\
1349
+	struct xa_state name = __XA_STATE(array, index, 0, 0)
1350
+
1351
+/**
1352
+ * XA_STATE_ORDER() - Declare an XArray operation state.
1353
+ * @name: Name of this operation state (usually xas).
1354
+ * @array: Array to operate on.
1355
+ * @index: Initial index of interest.
1356
+ * @order: Order of entry.
1357
+ *
1358
+ * Declare and initialise an xa_state on the stack.  This variant of
1359
+ * XA_STATE() allows you to specify the 'order' of the element you
1360
+ * want to operate on.`
1361
+ */
1362
+#define XA_STATE_ORDER(name, array, index, order)		\
1363
+	struct xa_state name = __XA_STATE(array,		\
1364
+			(index >> order) << order,		\
1365
+			order - (order % XA_CHUNK_SHIFT),	\
1366
+			(1U << (order % XA_CHUNK_SHIFT)) - 1)
1367
+
1368
+#define xas_marked(xas, mark)	xa_marked((xas)->xa, (mark))
1369
+#define xas_trylock(xas)	xa_trylock((xas)->xa)
1370
+#define xas_lock(xas)		xa_lock((xas)->xa)
1371
+#define xas_unlock(xas)		xa_unlock((xas)->xa)
1372
+#define xas_lock_bh(xas)	xa_lock_bh((xas)->xa)
1373
+#define xas_unlock_bh(xas)	xa_unlock_bh((xas)->xa)
1374
+#define xas_lock_irq(xas)	xa_lock_irq((xas)->xa)
1375
+#define xas_unlock_irq(xas)	xa_unlock_irq((xas)->xa)
1376
+#define xas_lock_irqsave(xas, flags) \
1377
+				xa_lock_irqsave((xas)->xa, flags)
1378
+#define xas_unlock_irqrestore(xas, flags) \
1379
+				xa_unlock_irqrestore((xas)->xa, flags)
1380
+
1381
+/**
1382
+ * xas_error() - Return an errno stored in the xa_state.
1383
+ * @xas: XArray operation state.
1384
+ *
1385
+ * Return: 0 if no error has been noted.  A negative errno if one has.
1386
+ */
1387
+static inline int xas_error(const struct xa_state *xas)
1388
+{
1389
+	return xa_err(xas->xa_node);
1390
+}
1391
+
1392
+/**
1393
+ * xas_set_err() - Note an error in the xa_state.
1394
+ * @xas: XArray operation state.
1395
+ * @err: Negative error number.
1396
+ *
1397
+ * Only call this function with a negative @err; zero or positive errors
1398
+ * will probably not behave the way you think they should.  If you want
1399
+ * to clear the error from an xa_state, use xas_reset().
1400
+ */
1401
+static inline void xas_set_err(struct xa_state *xas, long err)
1402
+{
1403
+	xas->xa_node = XA_ERROR(err);
1404
+}
1405
+
1406
+/**
1407
+ * xas_invalid() - Is the xas in a retry or error state?
1408
+ * @xas: XArray operation state.
1409
+ *
1410
+ * Return: %true if the xas cannot be used for operations.
1411
+ */
1412
+static inline bool xas_invalid(const struct xa_state *xas)
1413
+{
1414
+	return (unsigned long)xas->xa_node & 3;
1415
+}
1416
+
1417
+/**
1418
+ * xas_valid() - Is the xas a valid cursor into the array?
1419
+ * @xas: XArray operation state.
1420
+ *
1421
+ * Return: %true if the xas can be used for operations.
1422
+ */
1423
+static inline bool xas_valid(const struct xa_state *xas)
1424
+{
1425
+	return !xas_invalid(xas);
1426
+}
1427
+
1428
+/**
1429
+ * xas_is_node() - Does the xas point to a node?
1430
+ * @xas: XArray operation state.
1431
+ *
1432
+ * Return: %true if the xas currently references a node.
1433
+ */
1434
+static inline bool xas_is_node(const struct xa_state *xas)
1435
+{
1436
+	return xas_valid(xas) && xas->xa_node;
1437
+}
1438
+
1439
+/* True if the pointer is something other than a node */
1440
+static inline bool xas_not_node(struct xa_node *node)
1441
+{
1442
+	return ((unsigned long)node & 3) || !node;
1443
+}
1444
+
1445
+/* True if the node represents RESTART or an error */
1446
+static inline bool xas_frozen(struct xa_node *node)
1447
+{
1448
+	return (unsigned long)node & 2;
1449
+}
1450
+
1451
+/* True if the node represents head-of-tree, RESTART or BOUNDS */
1452
+static inline bool xas_top(struct xa_node *node)
1453
+{
1454
+	return node <= XAS_RESTART;
1455
+}
1456
+
1457
+/**
1458
+ * xas_reset() - Reset an XArray operation state.
1459
+ * @xas: XArray operation state.
1460
+ *
1461
+ * Resets the error or walk state of the @xas so future walks of the
1462
+ * array will start from the root.  Use this if you have dropped the
1463
+ * xarray lock and want to reuse the xa_state.
1464
+ *
1465
+ * Context: Any context.
1466
+ */
1467
+static inline void xas_reset(struct xa_state *xas)
1468
+{
1469
+	xas->xa_node = XAS_RESTART;
1470
+}
1471
+
1472
+/**
1473
+ * xas_retry() - Retry the operation if appropriate.
1474
+ * @xas: XArray operation state.
1475
+ * @entry: Entry from xarray.
1476
+ *
1477
+ * The advanced functions may sometimes return an internal entry, such as
1478
+ * a retry entry or a zero entry.  This function sets up the @xas to restart
1479
+ * the walk from the head of the array if needed.
1480
+ *
1481
+ * Context: Any context.
1482
+ * Return: true if the operation needs to be retried.
1483
+ */
1484
+static inline bool xas_retry(struct xa_state *xas, const void *entry)
1485
+{
1486
+	if (xa_is_zero(entry))
1487
+		return true;
1488
+	if (!xa_is_retry(entry))
1489
+		return false;
1490
+	xas_reset(xas);
1491
+	return true;
1492
+}
1493
+
1494
+void *xas_load(struct xa_state *);
1495
+void *xas_store(struct xa_state *, void *entry);
1496
+void *xas_find(struct xa_state *, unsigned long max);
1497
+void *xas_find_conflict(struct xa_state *);
1498
+
1499
+bool xas_get_mark(const struct xa_state *, xa_mark_t);
1500
+void xas_set_mark(const struct xa_state *, xa_mark_t);
1501
+void xas_clear_mark(const struct xa_state *, xa_mark_t);
1502
+void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
1503
+void xas_init_marks(const struct xa_state *);
1504
+
1505
+bool xas_nomem(struct xa_state *, gfp_t);
1506
+void xas_pause(struct xa_state *);
1507
+
1508
+void xas_create_range(struct xa_state *);
1509
+
1510
+#ifdef CONFIG_XARRAY_MULTI
1511
+int xa_get_order(struct xarray *, unsigned long index);
1512
+void xas_split(struct xa_state *, void *entry, unsigned int order);
1513
+void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
1514
+#else
1515
+static inline int xa_get_order(struct xarray *xa, unsigned long index)
1516
+{
1517
+	return 0;
1518
+}
1519
+
1520
+static inline void xas_split(struct xa_state *xas, void *entry,
1521
+		unsigned int order)
1522
+{
1523
+	xas_store(xas, entry);
1524
+}
1525
+
1526
+static inline void xas_split_alloc(struct xa_state *xas, void *entry,
1527
+		unsigned int order, gfp_t gfp)
1528
+{
1529
+}
1530
+#endif
1531
+
1532
+/**
1533
+ * xas_reload() - Refetch an entry from the xarray.
1534
+ * @xas: XArray operation state.
1535
+ *
1536
+ * Use this function to check that a previously loaded entry still has
1537
+ * the same value.  This is useful for the lockless pagecache lookup where
1538
+ * we walk the array with only the RCU lock to protect us, lock the page,
1539
+ * then check that the page hasn't moved since we looked it up.
1540
+ *
1541
+ * The caller guarantees that @xas is still valid.  If it may be in an
1542
+ * error or restart state, call xas_load() instead.
1543
+ *
1544
+ * Return: The entry at this location in the xarray.
1545
+ */
1546
+static inline void *xas_reload(struct xa_state *xas)
1547
+{
1548
+	struct xa_node *node = xas->xa_node;
1549
+	void *entry;
1550
+	char offset;
1551
+
1552
+	if (!node)
1553
+		return xa_head(xas->xa);
1554
+	if (IS_ENABLED(CONFIG_XARRAY_MULTI)) {
1555
+		offset = (xas->xa_index >> node->shift) & XA_CHUNK_MASK;
1556
+		entry = xa_entry(xas->xa, node, offset);
1557
+		if (!xa_is_sibling(entry))
1558
+			return entry;
1559
+		offset = xa_to_sibling(entry);
1560
+	} else {
1561
+		offset = xas->xa_offset;
1562
+	}
1563
+	return xa_entry(xas->xa, node, offset);
1564
+}
1565
+
1566
+/**
1567
+ * xas_set() - Set up XArray operation state for a different index.
1568
+ * @xas: XArray operation state.
1569
+ * @index: New index into the XArray.
1570
+ *
1571
+ * Move the operation state to refer to a different index.  This will
1572
+ * have the effect of starting a walk from the top; see xas_next()
1573
+ * to move to an adjacent index.
1574
+ */
1575
+static inline void xas_set(struct xa_state *xas, unsigned long index)
1576
+{
1577
+	xas->xa_index = index;
1578
+	xas->xa_node = XAS_RESTART;
1579
+}
1580
+
1581
+/**
1582
+ * xas_set_order() - Set up XArray operation state for a multislot entry.
1583
+ * @xas: XArray operation state.
1584
+ * @index: Target of the operation.
1585
+ * @order: Entry occupies 2^@order indices.
1586
+ */
1587
+static inline void xas_set_order(struct xa_state *xas, unsigned long index,
1588
+					unsigned int order)
1589
+{
1590
+#ifdef CONFIG_XARRAY_MULTI
1591
+	xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
1592
+	xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
1593
+	xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1594
+	xas->xa_node = XAS_RESTART;
1595
+#else
1596
+	BUG_ON(order > 0);
1597
+	xas_set(xas, index);
1598
+#endif
1599
+}
1600
+
1601
+/**
1602
+ * xas_set_update() - Set up XArray operation state for a callback.
1603
+ * @xas: XArray operation state.
1604
+ * @update: Function to call when updating a node.
1605
+ *
1606
+ * The XArray can notify a caller after it has updated an xa_node.
1607
+ * This is advanced functionality and is only needed by the page cache.
1608
+ */
1609
+static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
1610
+{
1611
+	xas->xa_update = update;
1612
+}
1613
+
1614
+/**
1615
+ * xas_next_entry() - Advance iterator to next present entry.
1616
+ * @xas: XArray operation state.
1617
+ * @max: Highest index to return.
1618
+ *
1619
+ * xas_next_entry() is an inline function to optimise xarray traversal for
1620
+ * speed.  It is equivalent to calling xas_find(), and will call xas_find()
1621
+ * for all the hard cases.
1622
+ *
1623
+ * Return: The next present entry after the one currently referred to by @xas.
1624
+ */
1625
+static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
1626
+{
1627
+	struct xa_node *node = xas->xa_node;
1628
+	void *entry;
1629
+
1630
+	if (unlikely(xas_not_node(node) || node->shift ||
1631
+			xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
1632
+		return xas_find(xas, max);
1633
+
1634
+	do {
1635
+		if (unlikely(xas->xa_index >= max))
1636
+			return xas_find(xas, max);
1637
+		if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
1638
+			return xas_find(xas, max);
1639
+		entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
1640
+		if (unlikely(xa_is_internal(entry)))
1641
+			return xas_find(xas, max);
1642
+		xas->xa_offset++;
1643
+		xas->xa_index++;
1644
+	} while (!entry);
1645
+
1646
+	return entry;
1647
+}
1648
+
1649
+/* Private */
1650
+static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
1651
+		xa_mark_t mark)
1652
+{
1653
+	unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
1654
+	unsigned int offset = xas->xa_offset;
1655
+
1656
+	if (advance)
1657
+		offset++;
1658
+	if (XA_CHUNK_SIZE == BITS_PER_LONG) {
1659
+		if (offset < XA_CHUNK_SIZE) {
1660
+			unsigned long data = *addr & (~0UL << offset);
1661
+			if (data)
1662
+				return __ffs(data);
1663
+		}
1664
+		return XA_CHUNK_SIZE;
1665
+	}
1666
+
1667
+	return find_next_bit(addr, XA_CHUNK_SIZE, offset);
1668
+}
1669
+
1670
+/**
1671
+ * xas_next_marked() - Advance iterator to next marked entry.
1672
+ * @xas: XArray operation state.
1673
+ * @max: Highest index to return.
1674
+ * @mark: Mark to search for.
1675
+ *
1676
+ * xas_next_marked() is an inline function to optimise xarray traversal for
1677
+ * speed.  It is equivalent to calling xas_find_marked(), and will call
1678
+ * xas_find_marked() for all the hard cases.
1679
+ *
1680
+ * Return: The next marked entry after the one currently referred to by @xas.
1681
+ */
1682
+static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
1683
+								xa_mark_t mark)
1684
+{
1685
+	struct xa_node *node = xas->xa_node;
1686
+	void *entry;
1687
+	unsigned int offset;
1688
+
1689
+	if (unlikely(xas_not_node(node) || node->shift))
1690
+		return xas_find_marked(xas, max, mark);
1691
+	offset = xas_find_chunk(xas, true, mark);
1692
+	xas->xa_offset = offset;
1693
+	xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
1694
+	if (xas->xa_index > max)
1695
+		return NULL;
1696
+	if (offset == XA_CHUNK_SIZE)
1697
+		return xas_find_marked(xas, max, mark);
1698
+	entry = xa_entry(xas->xa, node, offset);
1699
+	if (!entry)
1700
+		return xas_find_marked(xas, max, mark);
1701
+	return entry;
1702
+}
1703
+
1704
+/*
1705
+ * If iterating while holding a lock, drop the lock and reschedule
1706
+ * every %XA_CHECK_SCHED loops.
1707
+ */
1708
+enum {
1709
+	XA_CHECK_SCHED = 4096,
1710
+};
1711
+
1712
+/**
1713
+ * xas_for_each() - Iterate over a range of an XArray.
1714
+ * @xas: XArray operation state.
1715
+ * @entry: Entry retrieved from the array.
1716
+ * @max: Maximum index to retrieve from array.
1717
+ *
1718
+ * The loop body will be executed for each entry present in the xarray
1719
+ * between the current xas position and @max.  @entry will be set to
1720
+ * the entry retrieved from the xarray.  It is safe to delete entries
1721
+ * from the array in the loop body.  You should hold either the RCU lock
1722
+ * or the xa_lock while iterating.  If you need to drop the lock, call
1723
+ * xas_pause() first.
1724
+ */
1725
+#define xas_for_each(xas, entry, max) \
1726
+	for (entry = xas_find(xas, max); entry; \
1727
+	     entry = xas_next_entry(xas, max))
1728
+
1729
+/**
1730
+ * xas_for_each_marked() - Iterate over a range of an XArray.
1731
+ * @xas: XArray operation state.
1732
+ * @entry: Entry retrieved from the array.
1733
+ * @max: Maximum index to retrieve from array.
1734
+ * @mark: Mark to search for.
1735
+ *
1736
+ * The loop body will be executed for each marked entry in the xarray
1737
+ * between the current xas position and @max.  @entry will be set to
1738
+ * the entry retrieved from the xarray.  It is safe to delete entries
1739
+ * from the array in the loop body.  You should hold either the RCU lock
1740
+ * or the xa_lock while iterating.  If you need to drop the lock, call
1741
+ * xas_pause() first.
1742
+ */
1743
+#define xas_for_each_marked(xas, entry, max, mark) \
1744
+	for (entry = xas_find_marked(xas, max, mark); entry; \
1745
+	     entry = xas_next_marked(xas, max, mark))
1746
+
1747
+/**
1748
+ * xas_for_each_conflict() - Iterate over a range of an XArray.
1749
+ * @xas: XArray operation state.
1750
+ * @entry: Entry retrieved from the array.
1751
+ *
1752
+ * The loop body will be executed for each entry in the XArray that
1753
+ * lies within the range specified by @xas.  If the loop terminates
1754
+ * normally, @entry will be %NULL.  The user may break out of the loop,
1755
+ * which will leave @entry set to the conflicting entry.  The caller
1756
+ * may also call xa_set_err() to exit the loop while setting an error
1757
+ * to record the reason.
1758
+ */
1759
+#define xas_for_each_conflict(xas, entry) \
1760
+	while ((entry = xas_find_conflict(xas)))
1761
+
1762
+void *__xas_next(struct xa_state *);
1763
+void *__xas_prev(struct xa_state *);
1764
+
1765
+/**
1766
+ * xas_prev() - Move iterator to previous index.
1767
+ * @xas: XArray operation state.
1768
+ *
1769
+ * If the @xas was in an error state, it will remain in an error state
1770
+ * and this function will return %NULL.  If the @xas has never been walked,
1771
+ * it will have the effect of calling xas_load().  Otherwise one will be
1772
+ * subtracted from the index and the state will be walked to the correct
1773
+ * location in the array for the next operation.
1774
+ *
1775
+ * If the iterator was referencing index 0, this function wraps
1776
+ * around to %ULONG_MAX.
1777
+ *
1778
+ * Return: The entry at the new index.  This may be %NULL or an internal
1779
+ * entry.
1780
+ */
1781
+static inline void *xas_prev(struct xa_state *xas)
1782
+{
1783
+	struct xa_node *node = xas->xa_node;
1784
+
1785
+	if (unlikely(xas_not_node(node) || node->shift ||
1786
+				xas->xa_offset == 0))
1787
+		return __xas_prev(xas);
1788
+
1789
+	xas->xa_index--;
1790
+	xas->xa_offset--;
1791
+	return xa_entry(xas->xa, node, xas->xa_offset);
1792
+}
1793
+
1794
+/**
1795
+ * xas_next() - Move state to next index.
1796
+ * @xas: XArray operation state.
1797
+ *
1798
+ * If the @xas was in an error state, it will remain in an error state
1799
+ * and this function will return %NULL.  If the @xas has never been walked,
1800
+ * it will have the effect of calling xas_load().  Otherwise one will be
1801
+ * added to the index and the state will be walked to the correct
1802
+ * location in the array for the next operation.
1803
+ *
1804
+ * If the iterator was referencing index %ULONG_MAX, this function wraps
1805
+ * around to 0.
1806
+ *
1807
+ * Return: The entry at the new index.  This may be %NULL or an internal
1808
+ * entry.
1809
+ */
1810
+static inline void *xas_next(struct xa_state *xas)
1811
+{
1812
+	struct xa_node *node = xas->xa_node;
1813
+
1814
+	if (unlikely(xas_not_node(node) || node->shift ||
1815
+				xas->xa_offset == XA_CHUNK_MASK))
1816
+		return __xas_next(xas);
1817
+
1818
+	xas->xa_index++;
1819
+	xas->xa_offset++;
1820
+	return xa_entry(xas->xa, node, xas->xa_offset);
1821
+}
23
1822
 
24
1823
 #endif /* _LINUX_XARRAY_H */