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-rw-r--r--Documentation/core-api/xarray.rst15
1 files changed, 10 insertions, 5 deletions
diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst
index 5d54b27c6eba..ef6f9f98f595 100644
--- a/Documentation/core-api/xarray.rst
+++ b/Documentation/core-api/xarray.rst
@@ -85,7 +85,7 @@ which was at that index; if it returns the same entry which was passed as
If you want to only store a new entry to an index if the current entry
at that index is ``NULL``, you can use :c:func:`xa_insert` which
-returns ``-EEXIST`` if the entry is not empty.
+returns ``-EBUSY`` if the entry is not empty.
You can enquire whether a mark is set on an entry by using
:c:func:`xa_get_mark`. If the entry is not ``NULL``, you can set a mark
@@ -131,17 +131,23 @@ If you use :c:func:`DEFINE_XARRAY_ALLOC` to define the XArray, or
initialise it by passing ``XA_FLAGS_ALLOC`` to :c:func:`xa_init_flags`,
the XArray changes to track whether entries are in use or not.
-You can call :c:func:`xa_alloc` to store the entry at any unused index
+You can call :c:func:`xa_alloc` to store the entry at an unused index
in the XArray. If you need to modify the array from interrupt context,
you can use :c:func:`xa_alloc_bh` or :c:func:`xa_alloc_irq` to disable
interrupts while allocating the ID.
-Using :c:func:`xa_store`, :c:func:`xa_cmpxchg` or :c:func:`xa_insert`
-will mark the entry as being allocated. Unlike a normal XArray, storing
+Using :c:func:`xa_store`, :c:func:`xa_cmpxchg` or :c:func:`xa_insert` will
+also mark the entry as being allocated. Unlike a normal XArray, storing
``NULL`` will mark the entry as being in use, like :c:func:`xa_reserve`.
To free an entry, use :c:func:`xa_erase` (or :c:func:`xa_release` if
you only want to free the entry if it's ``NULL``).
+By default, the lowest free entry is allocated starting from 0. If you
+want to allocate entries starting at 1, it is more efficient to use
+:c:func:`DEFINE_XARRAY_ALLOC1` or ``XA_FLAGS_ALLOC1``. If you want to
+allocate IDs up to a maximum, then wrap back around to the lowest free
+ID, you can use :c:func:`xa_alloc_cyclic`.
+
You cannot use ``XA_MARK_0`` with an allocating XArray as this mark
is used to track whether an entry is free or not. The other marks are
available for your use.
@@ -209,7 +215,6 @@ Assumes xa_lock held on entry:
* :c:func:`__xa_erase`
* :c:func:`__xa_cmpxchg`
* :c:func:`__xa_alloc`
- * :c:func:`__xa_reserve`
* :c:func:`__xa_set_mark`
* :c:func:`__xa_clear_mark`