bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
+void *xa_find(struct xarray *xa, unsigned long *index,
+ unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
+void *xa_find_after(struct xarray *xa, unsigned long *index,
+ unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
/**
* xa_init() - Initialise an empty XArray.
return -EEXIST;
}
+/**
+ * xa_for_each() - Iterate over a portion of an XArray.
+ * @xa: XArray.
+ * @entry: Entry retrieved from array.
+ * @index: Index of @entry.
+ * @max: Maximum index to retrieve from array.
+ * @filter: Selection criterion.
+ *
+ * Initialise @index to the lowest index you want to retrieve from the
+ * array. During the iteration, @entry will have the value of the entry
+ * stored in @xa at @index. The iteration will skip all entries in the
+ * array which do not match @filter. You may modify @index during the
+ * iteration if you want to skip or reprocess indices. It is safe to modify
+ * the array during the iteration. At the end of the iteration, @entry will
+ * be set to NULL and @index will have a value less than or equal to max.
+ *
+ * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n). You have
+ * to handle your own locking with xas_for_each(), and if you have to unlock
+ * after each iteration, it will also end up being O(n.log(n)). xa_for_each()
+ * will spin if it hits a retry entry; if you intend to see retry entries,
+ * you should use the xas_for_each() iterator instead. The xas_for_each()
+ * iterator will expand into more inline code than xa_for_each().
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ */
+#define xa_for_each(xa, entry, index, max, filter) \
+ for (entry = xa_find(xa, &index, max, filter); entry; \
+ entry = xa_find_after(xa, &index, max, filter))
+
#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)
void *xas_load(struct xa_state *);
void *xas_store(struct xa_state *, void *entry);
+void *xas_find(struct xa_state *, unsigned long max);
bool xas_get_mark(const struct xa_state *, xa_mark_t);
void xas_set_mark(const struct xa_state *, xa_mark_t);
void xas_clear_mark(const struct xa_state *, xa_mark_t);
+void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
void xas_init_marks(const struct xa_state *);
bool xas_nomem(struct xa_state *, gfp_t);
+void xas_pause(struct xa_state *);
/**
* xas_reload() - Refetch an entry from the xarray.
xas->xa_update = update;
}
+/**
+ * xas_next_entry() - Advance iterator to next present entry.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ *
+ * xas_next_entry() is an inline function to optimise xarray traversal for
+ * speed. It is equivalent to calling xas_find(), and will call xas_find()
+ * for all the hard cases.
+ *
+ * Return: The next present entry after the one currently referred to by @xas.
+ */
+static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
+{
+ struct xa_node *node = xas->xa_node;
+ void *entry;
+
+ if (unlikely(xas_not_node(node) || node->shift ||
+ xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
+ return xas_find(xas, max);
+
+ do {
+ if (unlikely(xas->xa_index >= max))
+ return xas_find(xas, max);
+ if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
+ return xas_find(xas, max);
+ entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
+ if (unlikely(xa_is_internal(entry)))
+ return xas_find(xas, max);
+ xas->xa_offset++;
+ xas->xa_index++;
+ } while (!entry);
+
+ return entry;
+}
+
+/* Private */
+static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
+ xa_mark_t mark)
+{
+ unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
+ unsigned int offset = xas->xa_offset;
+
+ if (advance)
+ offset++;
+ if (XA_CHUNK_SIZE == BITS_PER_LONG) {
+ if (offset < XA_CHUNK_SIZE) {
+ unsigned long data = *addr & (~0UL << offset);
+ if (data)
+ return __ffs(data);
+ }
+ return XA_CHUNK_SIZE;
+ }
+
+ return find_next_bit(addr, XA_CHUNK_SIZE, offset);
+}
+
+/**
+ * xas_next_marked() - Advance iterator to next marked entry.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ * @mark: Mark to search for.
+ *
+ * xas_next_marked() is an inline function to optimise xarray traversal for
+ * speed. It is equivalent to calling xas_find_marked(), and will call
+ * xas_find_marked() for all the hard cases.
+ *
+ * Return: The next marked entry after the one currently referred to by @xas.
+ */
+static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
+ xa_mark_t mark)
+{
+ struct xa_node *node = xas->xa_node;
+ unsigned int offset;
+
+ if (unlikely(xas_not_node(node) || node->shift))
+ return xas_find_marked(xas, max, mark);
+ offset = xas_find_chunk(xas, true, mark);
+ xas->xa_offset = offset;
+ xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
+ if (xas->xa_index > max)
+ return NULL;
+ if (offset == XA_CHUNK_SIZE)
+ return xas_find_marked(xas, max, mark);
+ return xa_entry(xas->xa, node, offset);
+}
+
+/*
+ * If iterating while holding a lock, drop the lock and reschedule
+ * every %XA_CHECK_SCHED loops.
+ */
+enum {
+ XA_CHECK_SCHED = 4096,
+};
+
+/**
+ * xas_for_each() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ * @max: Maximum index to retrieve from array.
+ *
+ * The loop body will be executed for each entry present in the xarray
+ * between the current xas position and @max. @entry will be set to
+ * the entry retrieved from the xarray. It is safe to delete entries
+ * from the array in the loop body. You should hold either the RCU lock
+ * or the xa_lock while iterating. If you need to drop the lock, call
+ * xas_pause() first.
+ */
+#define xas_for_each(xas, entry, max) \
+ for (entry = xas_find(xas, max); entry; \
+ entry = xas_next_entry(xas, max))
+
+/**
+ * xas_for_each_marked() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ * @max: Maximum index to retrieve from array.
+ * @mark: Mark to search for.
+ *
+ * The loop body will be executed for each marked entry in the xarray
+ * between the current xas position and @max. @entry will be set to
+ * the entry retrieved from the xarray. It is safe to delete entries
+ * from the array in the loop body. You should hold either the RCU lock
+ * or the xa_lock while iterating. If you need to drop the lock, call
+ * xas_pause() first.
+ */
+#define xas_for_each_marked(xas, entry, max, mark) \
+ for (entry = xas_find_marked(xas, max, mark); entry; \
+ entry = xas_next_marked(xas, max, mark))
+
#endif /* _LINUX_XARRAY_H */
// XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL);
}
+static noinline void check_xas_retry(struct xarray *xa)
+{
+ XA_STATE(xas, xa, 0);
+ void *entry;
+
+ xa_store_index(xa, 0, GFP_KERNEL);
+ xa_store_index(xa, 1, GFP_KERNEL);
+
+ rcu_read_lock();
+ XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_value(0));
+ xa_erase_index(xa, 1);
+ XA_BUG_ON(xa, !xa_is_retry(xas_reload(&xas)));
+ XA_BUG_ON(xa, xas_retry(&xas, NULL));
+ XA_BUG_ON(xa, xas_retry(&xas, xa_mk_value(0)));
+ xas_reset(&xas);
+ XA_BUG_ON(xa, xas.xa_node != XAS_RESTART);
+ XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
+ XA_BUG_ON(xa, xas.xa_node != NULL);
+
+ XA_BUG_ON(xa, xa_store_index(xa, 1, GFP_KERNEL) != NULL);
+ XA_BUG_ON(xa, !xa_is_internal(xas_reload(&xas)));
+ xas.xa_node = XAS_RESTART;
+ XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
+ rcu_read_unlock();
+
+ /* Make sure we can iterate through retry entries */
+ xas_lock(&xas);
+ xas_set(&xas, 0);
+ xas_store(&xas, XA_RETRY_ENTRY);
+ xas_set(&xas, 1);
+ xas_store(&xas, XA_RETRY_ENTRY);
+
+ xas_set(&xas, 0);
+ xas_for_each(&xas, entry, ULONG_MAX) {
+ xas_store(&xas, xa_mk_value(xas.xa_index));
+ }
+ xas_unlock(&xas);
+
+ xa_erase_index(xa, 0);
+ xa_erase_index(xa, 1);
+}
+
static noinline void check_xa_load(struct xarray *xa)
{
unsigned long i, j;
XA_BUG_ON(xa, !xa_empty(xa));
}
+static noinline void check_xas_erase(struct xarray *xa)
+{
+ XA_STATE(xas, xa, 0);
+ void *entry;
+ unsigned long i, j;
+
+ for (i = 0; i < 200; i++) {
+ for (j = i; j < 2 * i + 17; j++) {
+ xas_set(&xas, j);
+ do {
+ xas_lock(&xas);
+ xas_store(&xas, xa_mk_value(j));
+ xas_unlock(&xas);
+ } while (xas_nomem(&xas, GFP_KERNEL));
+ }
+
+ xas_set(&xas, ULONG_MAX);
+ do {
+ xas_lock(&xas);
+ xas_store(&xas, xa_mk_value(0));
+ xas_unlock(&xas);
+ } while (xas_nomem(&xas, GFP_KERNEL));
+
+ xas_lock(&xas);
+ xas_store(&xas, NULL);
+
+ xas_set(&xas, 0);
+ j = i;
+ xas_for_each(&xas, entry, ULONG_MAX) {
+ XA_BUG_ON(xa, entry != xa_mk_value(j));
+ xas_store(&xas, NULL);
+ j++;
+ }
+ xas_unlock(&xas);
+ XA_BUG_ON(xa, !xa_empty(xa));
+ }
+}
+
static noinline void check_multi_store(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
#endif
}
+static noinline void check_multi_find(struct xarray *xa)
+{
+#ifdef CONFIG_XARRAY_MULTI
+ unsigned long index;
+
+ xa_store_order(xa, 12, 2, xa_mk_value(12), GFP_KERNEL);
+ XA_BUG_ON(xa, xa_store_index(xa, 16, GFP_KERNEL) != NULL);
+
+ index = 0;
+ XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
+ xa_mk_value(12));
+ XA_BUG_ON(xa, index != 12);
+ index = 13;
+ XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
+ xa_mk_value(12));
+ XA_BUG_ON(xa, (index < 12) || (index >= 16));
+ XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=
+ xa_mk_value(16));
+ XA_BUG_ON(xa, index != 16);
+
+ xa_erase_index(xa, 12);
+ xa_erase_index(xa, 16);
+ XA_BUG_ON(xa, !xa_empty(xa));
+#endif
+}
+
+static noinline void check_multi_find_2(struct xarray *xa)
+{
+ unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 10 : 1;
+ unsigned int i, j;
+ void *entry;
+
+ for (i = 0; i < max_order; i++) {
+ unsigned long index = 1UL << i;
+ for (j = 0; j < index; j++) {
+ XA_STATE(xas, xa, j + index);
+ xa_store_index(xa, index - 1, GFP_KERNEL);
+ xa_store_order(xa, index, i, xa_mk_value(index),
+ GFP_KERNEL);
+ rcu_read_lock();
+ xas_for_each(&xas, entry, ULONG_MAX) {
+ xa_erase_index(xa, index);
+ }
+ rcu_read_unlock();
+ xa_erase_index(xa, index - 1);
+ XA_BUG_ON(xa, !xa_empty(xa));
+ }
+ }
+}
+
+static noinline void check_find(struct xarray *xa)
+{
+ unsigned long i, j, k;
+
+ XA_BUG_ON(xa, !xa_empty(xa));
+
+ /*
+ * Check xa_find with all pairs between 0 and 99 inclusive,
+ * starting at every index between 0 and 99
+ */
+ for (i = 0; i < 100; i++) {
+ XA_BUG_ON(xa, xa_store_index(xa, i, GFP_KERNEL) != NULL);
+ xa_set_mark(xa, i, XA_MARK_0);
+ for (j = 0; j < i; j++) {
+ XA_BUG_ON(xa, xa_store_index(xa, j, GFP_KERNEL) !=
+ NULL);
+ xa_set_mark(xa, j, XA_MARK_0);
+ for (k = 0; k < 100; k++) {
+ unsigned long index = k;
+ void *entry = xa_find(xa, &index, ULONG_MAX,
+ XA_PRESENT);
+ if (k <= j)
+ XA_BUG_ON(xa, index != j);
+ else if (k <= i)
+ XA_BUG_ON(xa, index != i);
+ else
+ XA_BUG_ON(xa, entry != NULL);
+
+ index = k;
+ entry = xa_find(xa, &index, ULONG_MAX,
+ XA_MARK_0);
+ if (k <= j)
+ XA_BUG_ON(xa, index != j);
+ else if (k <= i)
+ XA_BUG_ON(xa, index != i);
+ else
+ XA_BUG_ON(xa, entry != NULL);
+ }
+ xa_erase_index(xa, j);
+ XA_BUG_ON(xa, xa_get_mark(xa, j, XA_MARK_0));
+ XA_BUG_ON(xa, !xa_get_mark(xa, i, XA_MARK_0));
+ }
+ xa_erase_index(xa, i);
+ XA_BUG_ON(xa, xa_get_mark(xa, i, XA_MARK_0));
+ }
+ XA_BUG_ON(xa, !xa_empty(xa));
+ check_multi_find(xa);
+ check_multi_find_2(xa);
+}
+
static DEFINE_XARRAY(array);
static int xarray_checks(void)
{
check_xa_err(&array);
+ check_xas_retry(&array);
check_xa_load(&array);
check_xa_mark(&array);
check_xa_shrink(&array);
+ check_xas_erase(&array);
check_cmpxchg(&array);
check_multi_store(&array);
+ check_find(&array);
printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
return (tests_run == tests_passed) ? 0 : -EINVAL;
return (index >> node->shift) & XA_CHUNK_MASK;
}
+static void xas_set_offset(struct xa_state *xas)
+{
+ xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
+}
+
/* move the index either forwards (find) or backwards (sibling slot) */
static void xas_move_index(struct xa_state *xas, unsigned long offset)
{
xas->xa_index += offset << shift;
}
+static void xas_advance(struct xa_state *xas)
+{
+ xas->xa_offset++;
+ xas_move_index(xas, xas->xa_offset);
+}
+
static void *set_bounds(struct xa_state *xas)
{
xas->xa_node = XAS_BOUNDS;
EXPORT_SYMBOL_GPL(xas_init_marks);
/**
+ * xas_pause() - Pause a walk to drop a lock.
+ * @xas: XArray operation state.
+ *
+ * Some users need to pause a walk and drop the lock they're holding in
+ * order to yield to a higher priority thread or carry out an operation
+ * on an entry. Those users should call this function before they drop
+ * the lock. It resets the @xas to be suitable for the next iteration
+ * of the loop after the user has reacquired the lock. If most entries
+ * found during a walk require you to call xas_pause(), the xa_for_each()
+ * iterator may be more appropriate.
+ *
+ * Note that xas_pause() only works for forward iteration. If a user needs
+ * to pause a reverse iteration, we will need a xas_pause_rev().
+ */
+void xas_pause(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_node;
+
+ if (xas_invalid(xas))
+ return;
+
+ if (node) {
+ unsigned int offset = xas->xa_offset;
+ while (++offset < XA_CHUNK_SIZE) {
+ if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
+ break;
+ }
+ xas->xa_index += (offset - xas->xa_offset) << node->shift;
+ } else {
+ xas->xa_index++;
+ }
+ xas->xa_node = XAS_RESTART;
+}
+EXPORT_SYMBOL_GPL(xas_pause);
+
+/**
+ * xas_find() - Find the next present entry in the XArray.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ *
+ * If the @xas has not yet been walked to an entry, return the entry
+ * which has an index >= xas.xa_index. If it has been walked, the entry
+ * currently being pointed at has been processed, and so we move to the
+ * next entry.
+ *
+ * If no entry is found and the array is smaller than @max, the iterator
+ * is set to the smallest index not yet in the array. This allows @xas
+ * to be immediately passed to xas_store().
+ *
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xas_find(struct xa_state *xas, unsigned long max)
+{
+ void *entry;
+
+ if (xas_error(xas))
+ return NULL;
+
+ if (!xas->xa_node) {
+ xas->xa_index = 1;
+ return set_bounds(xas);
+ } else if (xas_top(xas->xa_node)) {
+ entry = xas_load(xas);
+ if (entry || xas_not_node(xas->xa_node))
+ return entry;
+ } else if (!xas->xa_node->shift &&
+ xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
+ xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
+ }
+
+ xas_advance(xas);
+
+ while (xas->xa_node && (xas->xa_index <= max)) {
+ if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
+ xas->xa_offset = xas->xa_node->offset + 1;
+ xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+ continue;
+ }
+
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (xa_is_node(entry)) {
+ xas->xa_node = xa_to_node(entry);
+ xas->xa_offset = 0;
+ continue;
+ }
+ if (entry && !xa_is_sibling(entry))
+ return entry;
+
+ xas_advance(xas);
+ }
+
+ if (!xas->xa_node)
+ xas->xa_node = XAS_BOUNDS;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find);
+
+/**
+ * xas_find_marked() - Find the next marked entry in the XArray.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ * @mark: Mark number to search for.
+ *
+ * If the @xas has not yet been walked to an entry, return the marked entry
+ * which has an index >= xas.xa_index. If it has been walked, the entry
+ * currently being pointed at has been processed, and so we return the
+ * first marked entry with an index > xas.xa_index.
+ *
+ * If no marked entry is found and the array is smaller than @max, @xas is
+ * set to the bounds state and xas->xa_index is set to the smallest index
+ * not yet in the array. This allows @xas to be immediately passed to
+ * xas_store().
+ *
+ * If no entry is found before @max is reached, @xas is set to the restart
+ * state.
+ *
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
+{
+ bool advance = true;
+ unsigned int offset;
+ void *entry;
+
+ if (xas_error(xas))
+ return NULL;
+
+ if (!xas->xa_node) {
+ xas->xa_index = 1;
+ goto out;
+ } else if (xas_top(xas->xa_node)) {
+ advance = false;
+ entry = xa_head(xas->xa);
+ xas->xa_node = NULL;
+ if (xas->xa_index > max_index(entry))
+ goto bounds;
+ if (!xa_is_node(entry)) {
+ if (xa_marked(xas->xa, mark))
+ return entry;
+ xas->xa_index = 1;
+ goto out;
+ }
+ xas->xa_node = xa_to_node(entry);
+ xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
+ }
+
+ while (xas->xa_index <= max) {
+ if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
+ xas->xa_offset = xas->xa_node->offset + 1;
+ xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+ if (!xas->xa_node)
+ break;
+ advance = false;
+ continue;
+ }
+
+ if (!advance) {
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (xa_is_sibling(entry)) {
+ xas->xa_offset = xa_to_sibling(entry);
+ xas_move_index(xas, xas->xa_offset);
+ }
+ }
+
+ offset = xas_find_chunk(xas, advance, mark);
+ if (offset > xas->xa_offset) {
+ advance = false;
+ xas_move_index(xas, offset);
+ /* Mind the wrap */
+ if ((xas->xa_index - 1) >= max)
+ goto max;
+ xas->xa_offset = offset;
+ if (offset == XA_CHUNK_SIZE)
+ continue;
+ }
+
+ entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+ if (!xa_is_node(entry))
+ return entry;
+ xas->xa_node = xa_to_node(entry);
+ xas_set_offset(xas);
+ }
+
+out:
+ if (!max)
+ goto max;
+bounds:
+ xas->xa_node = XAS_BOUNDS;
+ return NULL;
+max:
+ xas->xa_node = XAS_RESTART;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find_marked);
+
+/**
* xa_init_flags() - Initialise an empty XArray with flags.
* @xa: XArray.
* @flags: XA_FLAG values.
}
EXPORT_SYMBOL(xa_clear_mark);
+/**
+ * xa_find() - Search the XArray for an entry.
+ * @xa: XArray.
+ * @indexp: Pointer to an index.
+ * @max: Maximum index to search to.
+ * @filter: Selection criterion.
+ *
+ * Finds the entry in @xa which matches the @filter, and has the lowest
+ * index that is at least @indexp and no more than @max.
+ * If an entry is found, @indexp is updated to be the index of the entry.
+ * This function is protected by the RCU read lock, so it may not find
+ * entries which are being simultaneously added. It will not return an
+ * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xa_find(struct xarray *xa, unsigned long *indexp,
+ unsigned long max, xa_mark_t filter)
+{
+ XA_STATE(xas, xa, *indexp);
+ void *entry;
+
+ rcu_read_lock();
+ do {
+ if ((__force unsigned int)filter < XA_MAX_MARKS)
+ entry = xas_find_marked(&xas, max, filter);
+ else
+ entry = xas_find(&xas, max);
+ } while (xas_retry(&xas, entry));
+ rcu_read_unlock();
+
+ if (entry)
+ *indexp = xas.xa_index;
+ return entry;
+}
+EXPORT_SYMBOL(xa_find);
+
+/**
+ * xa_find_after() - Search the XArray for a present entry.
+ * @xa: XArray.
+ * @indexp: Pointer to an index.
+ * @max: Maximum index to search to.
+ * @filter: Selection criterion.
+ *
+ * Finds the entry in @xa which matches the @filter and has the lowest
+ * index that is above @indexp and no more than @max.
+ * If an entry is found, @indexp is updated to be the index of the entry.
+ * This function is protected by the RCU read lock, so it may miss entries
+ * which are being simultaneously added. It will not return an
+ * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The pointer, if found, otherwise %NULL.
+ */
+void *xa_find_after(struct xarray *xa, unsigned long *indexp,
+ unsigned long max, xa_mark_t filter)
+{
+ XA_STATE(xas, xa, *indexp + 1);
+ void *entry;
+
+ rcu_read_lock();
+ for (;;) {
+ if ((__force unsigned int)filter < XA_MAX_MARKS)
+ entry = xas_find_marked(&xas, max, filter);
+ else
+ entry = xas_find(&xas, max);
+ if (xas.xa_shift) {
+ if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
+ continue;
+ } else {
+ if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))
+ continue;
+ }
+ if (!xas_retry(&xas, entry))
+ break;
+ }
+ rcu_read_unlock();
+
+ if (entry)
+ *indexp = xas.xa_index;
+ return entry;
+}
+EXPORT_SYMBOL(xa_find_after);
+
#ifdef XA_DEBUG
void xa_dump_node(const struct xa_node *node)
{
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