KEYS: Replace assoc_array with rhashtable

index 1f9601ef22f8..792449d356cf 100755
@@ -746,7 +746,7 @@ test_keyring_inactive_when_empty() {
     log_info "TEST: Verify dm-verity keyring is inactive when sealed empty"
 
     # When keyring_unsealed=0, the keyring is sealed immediately while empty
-    # This means it should NOT be used for verification (nr_leaves_on_tree=0)
+    # An empty keyring should NOT be used for verification.
 
     log_info "Keyring state (should be empty and sealed):"
     list_keyring_keys

index f4510d8cb485..3f64d60d0f8a 100644
@@ -5,7 +5,6 @@
 
 menuconfig KEYS
 	bool "Enable access key retention support"
-	select ASSOCIATIVE_ARRAY
 	help
 	  This option provides support for retaining authentication tokens and
 	  access keys in the kernel.

deleted file mode 100644
index 19d89f92bf8d..000000000000
@@ -1,564 +0,0 @@
-========================================
-Generic Associative Array Implementation
-========================================
-
-Overview
-========
-
-This associative array implementation is an object container with the following
-properties:
-
-1. Objects are opaque pointers.  The implementation does not care where they
-   point (if anywhere) or what they point to (if anything).
-
-   .. note::
-
-      Pointers to objects _must_ be zero in the least significant bit.
-
-2. Objects do not need to contain linkage blocks for use by the array.  This
-   permits an object to be located in multiple arrays simultaneously.
-   Rather, the array is made up of metadata blocks that point to objects.
-
-3. Objects require index keys to locate them within the array.
-
-4. Index keys must be unique.  Inserting an object with the same key as one
-   already in the array will replace the old object.
-
-5. Index keys can be of any length and can be of different lengths.
-
-6. Index keys should encode the length early on, before any variation due to
-   length is seen.
-
-7. Index keys can include a hash to scatter objects throughout the array.
-
-8. The array can iterated over.  The objects will not necessarily come out in
-   key order.
-
-9. The array can be iterated over while it is being modified, provided the
-   RCU readlock is being held by the iterator.  Note, however, under these
-   circumstances, some objects may be seen more than once.  If this is a
-   problem, the iterator should lock against modification.  Objects will not
-   be missed, however, unless deleted.
-
-10. Objects in the array can be looked up by means of their index key.
-
-11. Objects can be looked up while the array is being modified, provided the
-    RCU readlock is being held by the thread doing the look up.
-
-The implementation uses a tree of 16-pointer nodes internally that are indexed
-on each level by nibbles from the index key in the same manner as in a radix
-tree.  To improve memory efficiency, shortcuts can be emplaced to skip over
-what would otherwise be a series of single-occupancy nodes.  Further, nodes
-pack leaf object pointers into spare space in the node rather than making an
-extra branch until as such time an object needs to be added to a full node.
-
-
-The Public API
-==============
-
-The public API can be found in ``<linux/assoc_array.h>``.  The associative
-array is rooted on the following structure::
-
-    struct assoc_array {
-            ...
-    };
-
-The code is selected by enabling ``CONFIG_ASSOCIATIVE_ARRAY`` with::
-
-    ./script/config -e ASSOCIATIVE_ARRAY
-
-
-Edit Script
------------
-
-The insertion and deletion functions produce an 'edit script' that can later be
-applied to effect the changes without risking ``ENOMEM``. This retains the
-preallocated metadata blocks that will be installed in the internal tree and
-keeps track of the metadata blocks that will be removed from the tree when the
-script is applied.
-
-This is also used to keep track of dead blocks and dead objects after the
-script has been applied so that they can be freed later.  The freeing is done
-after an RCU grace period has passed - thus allowing access functions to
-proceed under the RCU read lock.
-
-The script appears as outside of the API as a pointer of the type::
-
-    struct assoc_array_edit;
-
-There are two functions for dealing with the script:
-
-1. Apply an edit script::
-
-    void assoc_array_apply_edit(struct assoc_array_edit *edit);
-
-   This will perform the edit functions, interpolating various write barriers
-   to permit accesses under the RCU read lock to continue.  The edit script
-   will then be passed to ``call_rcu()`` to free it and any dead stuff it
-   points to.
-
-2. Cancel an edit script::
-
-    void assoc_array_cancel_edit(struct assoc_array_edit *edit);
-
-   This frees the edit script and all preallocated memory immediately. If
-   this was for insertion, the new object is *not* released by this function,
-   but must rather be released by the caller.
-
-These functions are guaranteed not to fail.
-
-
-Operations Table
-----------------
-
-Various functions take a table of operations::
-
-    struct assoc_array_ops {
-            ...
-    };
-
-This points to a number of methods, all of which need to be provided:
-
-1. Get a chunk of index key from caller data::
-
-    unsigned long (*get_key_chunk)(const void *index_key, int level);
-
-   This should return a chunk of caller-supplied index key starting at the
-   *bit* position given by the level argument.  The level argument will be a
-   multiple of ``ASSOC_ARRAY_KEY_CHUNK_SIZE`` and the function should return
-   ``ASSOC_ARRAY_KEY_CHUNK_SIZE bits``.  No error is possible.
-
-
-2. Get a chunk of an object's index key::
-
-    unsigned long (*get_object_key_chunk)(const void *object, int level);
-
-   As the previous function, but gets its data from an object in the array
-   rather than from a caller-supplied index key.
-
-
-3. See if this is the object we're looking for::
-
-    bool (*compare_object)(const void *object, const void *index_key);
-
-   Compare the object against an index key and return ``true`` if it matches
-   and ``false`` if it doesn't.
-
-
-4. Diff the index keys of two objects::
-
-    int (*diff_objects)(const void *object, const void *index_key);
-
-   Return the bit position at which the index key of the specified object
-   differs from the given index key or -1 if they are the same.
-
-
-5. Free an object::
-
-    void (*free_object)(void *object);
-
-   Free the specified object.  Note that this may be called an RCU grace period
-   after ``assoc_array_apply_edit()`` was called, so ``synchronize_rcu()`` may
-   be necessary on module unloading.
-
-
-Manipulation Functions
-----------------------
-
-There are a number of functions for manipulating an associative array:
-
-1. Initialise an associative array::
-
-    void assoc_array_init(struct assoc_array *array);
-
-   This initialises the base structure for an associative array.  It can't fail.
-
-
-2. Insert/replace an object in an associative array::
-
-    struct assoc_array_edit *
-    assoc_array_insert(struct assoc_array *array,
-                       const struct assoc_array_ops *ops,
-                       const void *index_key,
-                       void *object);
-
-   This inserts the given object into the array.  Note that the least
-   significant bit of the pointer must be zero as it's used to type-mark
-   pointers internally.
-
-   If an object already exists for that key then it will be replaced with the
-   new object and the old one will be freed automatically.
-
-   The ``index_key`` argument should hold index key information and is
-   passed to the methods in the ops table when they are called.
-
-   This function makes no alteration to the array itself, but rather returns
-   an edit script that must be applied.  ``-ENOMEM`` is returned in the case of
-   an out-of-memory error.
-
-   The caller should lock exclusively against other modifiers of the array.
-
-
-3. Delete an object from an associative array::
-
-    struct assoc_array_edit *
-    assoc_array_delete(struct assoc_array *array,
-                       const struct assoc_array_ops *ops,
-                       const void *index_key);
-
-   This deletes an object that matches the specified data from the array.
-
-   The ``index_key`` argument should hold index key information and is
-   passed to the methods in the ops table when they are called.
-
-   This function makes no alteration to the array itself, but rather returns
-   an edit script that must be applied.  ``-ENOMEM`` is returned in the case of
-   an out-of-memory error.  ``NULL`` will be returned if the specified object
-   is not found within the array.
-
-The caller should lock exclusively against other modifiers of the array.
-
-
-4. Delete all objects from an associative array::
-
-    struct assoc_array_edit *
-    assoc_array_clear(struct assoc_array *array,
-                      const struct assoc_array_ops *ops);
-
-   This deletes all the objects from an associative array and leaves it
-   completely empty.
-
-   This function makes no alteration to the array itself, but rather returns
-   an edit script that must be applied.  ``-ENOMEM`` is returned in the case of
-   an out-of-memory error.
-
-   The caller should lock exclusively against other modifiers of the array.
-
-
-5. Destroy an associative array, deleting all objects::
-
-    void assoc_array_destroy(struct assoc_array *array,
-                             const struct assoc_array_ops *ops);
-
-   This destroys the contents of the associative array and leaves it
-   completely empty.  It is not permitted for another thread to be traversing
-   the array under the RCU read lock at the same time as this function is
-   destroying it as no RCU deferral is performed on memory release -
-   something that would require memory to be allocated.
-
-   The caller should lock exclusively against other modifiers and accessors
-   of the array.
-
-
-6. Garbage collect an associative array::
-
-    int assoc_array_gc(struct assoc_array *array,
-                       const struct assoc_array_ops *ops,
-                       bool (*iterator)(void *object, void *iterator_data),
-                       void *iterator_data);
-
-   This iterates over the objects in an associative array and passes each one
-   to ``iterator()``.  If ``iterator()`` returns ``true``, the object is kept.
-   If it returns ``false``, the object will be freed.  If the ``iterator()``
-   function returns ``true``, it must perform any appropriate refcount
-   incrementing on the object before returning.
-
-   The internal tree will be packed down if possible as part of the iteration
-   to reduce the number of nodes in it.
-
-   The ``iterator_data`` is passed directly to ``iterator()`` and is otherwise
-   ignored by the function.
-
-   The function will return ``0`` if successful and ``-ENOMEM`` if there wasn't
-   enough memory.
-
-   It is possible for other threads to iterate over or search the array under
-   the RCU read lock while this function is in progress.  The caller should
-   lock exclusively against other modifiers of the array.
-
-
-Access Functions
-----------------
-
-There are two functions for accessing an associative array:
-
-1. Iterate over all the objects in an associative array::
-
-    int assoc_array_iterate(const struct assoc_array *array,
-                            int (*iterator)(const void *object,
-                                            void *iterator_data),
-                            void *iterator_data);
-
-   This passes each object in the array to the iterator callback function.
-   ``iterator_data`` is private data for that function.
-
-   This may be used on an array at the same time as the array is being
-   modified, provided the RCU read lock is held.  Under such circumstances,
-   it is possible for the iteration function to see some objects twice.  If
-   this is a problem, then modification should be locked against.  The
-   iteration algorithm should not, however, miss any objects.
-
-   The function will return ``0`` if no objects were in the array or else it
-   will return the result of the last iterator function called.  Iteration
-   stops immediately if any call to the iteration function results in a
-   non-zero return.
-
-
-2. Find an object in an associative array::
-
-    void *assoc_array_find(const struct assoc_array *array,
-                           const struct assoc_array_ops *ops,
-                           const void *index_key);
-
-   This walks through the array's internal tree directly to the object
-   specified by the index key.
-
-   This may be used on an array at the same time as the array is being
-   modified, provided the RCU read lock is held.
-
-   The function will return the object if found (and set ``*_type`` to the
-   object type) or will return ``NULL`` if the object was not found.
-
-
-Index Key Form
---------------
-
-The index key can be of any form, but since the algorithms aren't told how long
-the key is, it is strongly recommended that the index key includes its length
-very early on before any variation due to the length would have an effect on
-comparisons.
-
-This will cause leaves with different length keys to scatter away from each
-other - and those with the same length keys to cluster together.
-
-It is also recommended that the index key begin with a hash of the rest of the
-key to maximise scattering throughout keyspace.
-
-The better the scattering, the wider and lower the internal tree will be.
-
-Poor scattering isn't too much of a problem as there are shortcuts and nodes
-can contain mixtures of leaves and metadata pointers.
-
-The index key is read in chunks of machine word.  Each chunk is subdivided into
-one nibble (4 bits) per level, so on a 32-bit CPU this is good for 8 levels and
-on a 64-bit CPU, 16 levels.  Unless the scattering is really poor, it is
-unlikely that more than one word of any particular index key will have to be
-used.
-
-
-Internal Workings
-=================
-
-The associative array data structure has an internal tree.  This tree is
-constructed of two types of metadata blocks: nodes and shortcuts.
-
-A node is an array of slots.  Each slot can contain one of four things:
-
-* A NULL pointer, indicating that the slot is empty.
-* A pointer to an object (a leaf).
-* A pointer to a node at the next level.
-* A pointer to a shortcut.
-
-
-Basic Internal Tree Layout
---------------------------
-
-Ignoring shortcuts for the moment, the nodes form a multilevel tree.  The index
-key space is strictly subdivided by the nodes in the tree and nodes occur on
-fixed levels.  For example::
-
- Level: 0               1               2               3
-        =============== =============== =============== ===============
-                                                        NODE D
-                        NODE B          NODE C  +------>+---+
-                +------>+---+   +------>+---+   |       | 0 |
-        NODE A  |       | 0 |   |       | 0 |   |       +---+
-        +---+   |       +---+   |       +---+   |       :   :
-        | 0 |   |       :   :   |       :   :   |       +---+
-        +---+   |       +---+   |       +---+   |       | f |
-        | 1 |---+       | 3 |---+       | 7 |---+       +---+
-        +---+           +---+           +---+
-        :   :           :   :           | 8 |---+
-        +---+           +---+           +---+   |       NODE E
-        | e |---+       | f |           :   :   +------>+---+
-        +---+   |       +---+           +---+           | 0 |
-        | f |   |                       | f |           +---+
-        +---+   |                       +---+           :   :
-                |       NODE F                          +---+
-                +------>+---+                           | f |
-                        | 0 |           NODE G          +---+
-                        +---+   +------>+---+
-                        :   :   |       | 0 |
-                        +---+   |       +---+
-                        | 6 |---+       :   :
-                        +---+           +---+
-                        :   :           | f |
-                        +---+           +---+
-                        | f |
-                        +---+
-
-In the above example, there are 7 nodes (A-G), each with 16 slots (0-f).
-Assuming no other meta data nodes in the tree, the key space is divided
-thusly:
-
-    ===========     ====
-    KEY PREFIX      NODE
-    ===========     ====
-    137*            D
-    138*            E
-    13[0-69-f]*     C
-    1[0-24-f]*      B
-    e6*             G
-    e[0-57-f]*      F
-    [02-df]*        A
-    ===========     ====
-
-So, for instance, keys with the following example index keys will be found in
-the appropriate nodes:
-
-    =============== ======= ====
-    INDEX KEY       PREFIX  NODE
-    =============== ======= ====
-    13694892892489  13      C
-    13795289025897  137     D
-    13889dde88793   138     E
-    138bbb89003093  138     E
-    1394879524789   12      C
-    1458952489      1       B
-    9431809de993ba  \-      A
-    b4542910809cd   \-      A
-    e5284310def98   e       F
-    e68428974237    e6      G
-    e7fffcbd443     e       F
-    f3842239082     \-      A
-    =============== ======= ====
-
-To save memory, if a node can hold all the leaves in its portion of keyspace,
-then the node will have all those leaves in it and will not have any metadata
-pointers - even if some of those leaves would like to be in the same slot.
-
-A node can contain a heterogeneous mix of leaves and metadata pointers.
-Metadata pointers must be in the slots that match their subdivisions of key
-space.  The leaves can be in any slot not occupied by a metadata pointer.  It
-is guaranteed that none of the leaves in a node will match a slot occupied by a
-metadata pointer.  If the metadata pointer is there, any leaf whose key matches
-the metadata key prefix must be in the subtree that the metadata pointer points
-to.
-
-In the above example list of index keys, node A will contain:
-
-    ====    =============== ==================
-    SLOT    CONTENT         INDEX KEY (PREFIX)
-    ====    =============== ==================
-    1       PTR TO NODE B   1*
-    any     LEAF            9431809de993ba
-    any     LEAF            b4542910809cd
-    e       PTR TO NODE F   e*
-    any     LEAF            f3842239082
-    ====    =============== ==================
-
-and node B:
-
-    ====    =============== ==================
-    SLOT    CONTENT         INDEX KEY (PREFIX)
-    ====    =============== ==================
-    3       PTR TO NODE C   13*
-    any     LEAF            1458952489
-    ====    =============== ==================
-
-
-Shortcuts
----------
-
-Shortcuts are metadata records that jump over a piece of keyspace.  A shortcut
-is a replacement for a series of single-occupancy nodes ascending through the
-levels.  Shortcuts exist to save memory and to speed up traversal.
-
-It is possible for the root of the tree to be a shortcut - say, for example,
-the tree contains at least 17 nodes all with key prefix ``1111``.  The
-insertion algorithm will insert a shortcut to skip over the ``1111`` keyspace
-in a single bound and get to the fourth level where these actually become
-different.
-
-
-Splitting And Collapsing Nodes
-------------------------------
-
-Each node has a maximum capacity of 16 leaves and metadata pointers.  If the
-insertion algorithm finds that it is trying to insert a 17th object into a
-node, that node will be split such that at least two leaves that have a common
-key segment at that level end up in a separate node rooted on that slot for
-that common key segment.
-
-If the leaves in a full node and the leaf that is being inserted are
-sufficiently similar, then a shortcut will be inserted into the tree.
-
-When the number of objects in the subtree rooted at a node falls to 16 or
-fewer, then the subtree will be collapsed down to a single node - and this will
-ripple towards the root if possible.
-
-
-Non-Recursive Iteration
------------------------
-
-Each node and shortcut contains a back pointer to its parent and the number of
-slot in that parent that points to it.  None-recursive iteration uses these to
-proceed rootwards through the tree, going to the parent node, slot N + 1 to
-make sure progress is made without the need for a stack.
-
-The backpointers, however, make simultaneous alteration and iteration tricky.
-
-
-Simultaneous Alteration And Iteration
--------------------------------------
-
-There are a number of cases to consider:
-
-1. Simple insert/replace.  This involves simply replacing a NULL or old
-   matching leaf pointer with the pointer to the new leaf after a barrier.
-   The metadata blocks don't change otherwise.  An old leaf won't be freed
-   until after the RCU grace period.
-
-2. Simple delete.  This involves just clearing an old matching leaf.  The
-   metadata blocks don't change otherwise.  The old leaf won't be freed until
-   after the RCU grace period.
-
-3. Insertion replacing part of a subtree that we haven't yet entered.  This
-   may involve replacement of part of that subtree - but that won't affect
-   the iteration as we won't have reached the pointer to it yet and the
-   ancestry blocks are not replaced (the layout of those does not change).
-
-4. Insertion replacing nodes that we're actively processing.  This isn't a
-   problem as we've passed the anchoring pointer and won't switch onto the
-   new layout until we follow the back pointers - at which point we've
-   already examined the leaves in the replaced node (we iterate over all the
-   leaves in a node before following any of its metadata pointers).
-
-   We might, however, re-see some leaves that have been split out into a new
-   branch that's in a slot further along than we were at.
-
-5. Insertion replacing nodes that we're processing a dependent branch of.
-   This won't affect us until we follow the back pointers.  Similar to (4).
-
-6. Deletion collapsing a branch under us.  This doesn't affect us because the
-   back pointers will get us back to the parent of the new node before we
-   could see the new node.  The entire collapsed subtree is thrown away
-   unchanged - and will still be rooted on the same slot, so we shouldn't
-   process it a second time as we'll go back to slot + 1.
-
-.. note::
-
-   Under some circumstances, we need to simultaneously change the parent
-   pointer and the parent slot pointer on a node (say, for example, we
-   inserted another node before it and moved it up a level).  We cannot do
-   this without locking against a read - so we have to replace that node too.
-
-   However, when we're changing a shortcut into a node this isn't a problem
-   as shortcuts only have one slot and so the parent slot number isn't used
-   when traversing backwards over one.  This means that it's okay to change
-   the slot number first - provided suitable barriers are used to make sure
-   the parent slot number is read after the back pointer.
-
-Obsolete blocks and leaves are freed up after an RCU grace period has passed,
-so as long as anyone doing walking or iteration holds the RCU read lock, the
-old superstructure should not go away on them.

index 92f91c6a0d79..d56c60663b0c 100644
@@ -38,7 +38,6 @@ Library functionality that is used throughout the kernel.
    kobject
    kref
    cleanup
-   assoc_array
    folio_queue
    xarray
    maple_tree

473 lines not on this page · raw message

index 453a02cd1f44..ec4b03b2a0a6 100644
@@ -41,7 +41,6 @@
 
    kobject
    kref
-   assoc_array
    xarray
    rbtree
    idr

index 4e6b34c3346d..9b3dd46c6799 100644
@@ -349,20 +349,6 @@ config XARRAY_MULTI
 	  Support entries which occupy multiple consecutive indices in the
 	  XArray.
 
-config ASSOCIATIVE_ARRAY
-	bool
-	help
-	  Generic associative array.  Can be searched and iterated over whilst
-	  it is being modified.  It is also reasonably quick to search and
-	  modify.  The algorithms are non-recursive, and the trees are highly
-	  capacious.
-
-	  See:
-
-		Documentation/core-api/assoc_array.rst
-
-	  for more information.
-
 config CLOSURES
 	bool
 

index a2afe954805c..4777dfcc8244 100644
@@ -141,7 +141,6 @@ obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
 
 obj-$(CONFIG_BTREE) += btree.o
 obj-$(CONFIG_INTERVAL_TREE) += interval_tree.o
-obj-$(CONFIG_ASSOCIATIVE_ARRAY) += assoc_array.o
 obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
 obj-$(CONFIG_LIST_HARDENED) += list_debug.o
 obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o