XArray: Fix Documentation

Minor fixes.
Signed-off-by: NMatthew Wilcox <willy@infradead.org>

Documentation/core-api/xarray.rst

@@ -74,7 +74,8 @@ using :c:func:`xa_load`.  xa_store will overwrite any entry with the
 new entry and return the previous entry stored at that index.  You can
 use :c:func:`xa_erase` instead of calling :c:func:`xa_store` with a
 ``NULL`` entry.  There is no difference between an entry that has never
-been stored to and one that has most recently had ``NULL`` stored to it.
+been stored to, one that has been erased and one that has most recently
+had ``NULL`` stored to it.
 
 You can conditionally replace an entry at an index by using
 :c:func:`xa_cmpxchg`.  Like :c:func:`cmpxchg`, it will only succeed if
@@ -114,6 +115,9 @@ unused entry.  If another user has stored to the entry in the meantime,
 :c:func:`xa_release` will do nothing; if instead you want the entry to
 become ``NULL``, you should use :c:func:`xa_erase`.
 
+If all entries in the array are ``NULL``, the :c:func:`xa_empty` function
+will return ``true``.
+
 Finally, you can remove all entries from an XArray by calling
 :c:func:`xa_destroy`.  If the XArray entries are pointers, you may wish
 to free the entries first.  You can do this by iterating over all present

include/linux/xarray.h

@@ -487,7 +487,7 @@ static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
  * the third argument.  The XArray does not need to allocate memory, so
  * the user does not need to provide GFP flags.
  *
- * Context: Process context.  Takes and releases the xa_lock while
+ * Context: Any context.  Takes and releases the xa_lock while
  * disabling softirqs.
  * Return: The entry which used to be at this index.
  */
@@ -622,7 +622,7 @@ static inline int xa_alloc(struct xarray *xa, u32 *id, u32 max, void *entry,
  * Updates the @id pointer with the index, then stores the entry at that
  * index.  A concurrent lookup will not see an uninitialised @id.
  *
- * Context: Process context.  Takes and releases the xa_lock while
+ * Context: Any context.  Takes and releases the xa_lock while
  * disabling softirqs.  May sleep if the @gfp flags permit.
  * Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if
  * there is no more space in the XArray.

lib/xarray.c

@@ -610,8 +610,8 @@ static int xas_expand(struct xa_state *xas, void *head)
  * (see the xa_cmpxchg() implementation for an example).
  *
  * Return: If the slot already existed, returns the contents of this slot.
- * If the slot was newly created, returns NULL.  If it failed to create the
- * slot, returns NULL and indicates the error in @xas.
+ * If the slot was newly created, returns %NULL.  If it failed to create the
+ * slot, returns %NULL and indicates the error in @xas.
  */
 static void *xas_create(struct xa_state *xas)
 {
@@ -1640,7 +1640,7 @@ EXPORT_SYMBOL(__xa_alloc);
  * @index: Index of entry.
  * @mark: Mark number.
  *
- * Attempting to set a mark on a NULL entry does not succeed.
+ * Attempting to set a mark on a %NULL entry does not succeed.
  *
  * Context: Any context.  Expects xa_lock to be held on entry.
  */
@@ -1710,7 +1710,7 @@ EXPORT_SYMBOL(xa_get_mark);
  * @index: Index of entry.
  * @mark: Mark number.
  *
- * Attempting to set a mark on a NULL entry does not succeed.
+ * Attempting to set a mark on a %NULL entry does not succeed.
  *
  * Context: Process context.  Takes and releases the xa_lock.
  */
@@ -1879,7 +1879,7 @@ static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
  *
  * The @filter may be an XArray mark value, in which case entries which are
  * marked with that mark will be copied.  It may also be %XA_PRESENT, in
- * which case all entries which are not NULL will be copied.
+ * which case all entries which are not %NULL will be copied.
  *
  * The entries returned may not represent a snapshot of the XArray at a
  * moment in time.  For example, if another thread stores to index 5, then