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| -rw-r--r-- | Documentation/core-api/assoc_array.rst | 167 |
1 files changed, 84 insertions, 83 deletions
diff --git a/Documentation/core-api/assoc_array.rst b/Documentation/core-api/assoc_array.rst index 792bbf9939e1..61c7ba1e7b87 100644 --- a/Documentation/core-api/assoc_array.rst +++ b/Documentation/core-api/assoc_array.rst @@ -92,18 +92,18 @@ There are two functions for dealing with the 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. + 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. + 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. @@ -123,43 +123,43 @@ This points to a number of methods, all of which need to be provided: 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. + 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. + 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. + 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. + 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. + 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 @@ -171,7 +171,7 @@ There are a number of functions for manipulating an associative array: void assoc_array_init(struct assoc_array *array); -This initialises the base structure for an associative array. It can't fail. + This initialises the base structure for an associative array. It can't fail. 2. Insert/replace an object in an associative array:: @@ -182,21 +182,21 @@ This initialises the base structure for an associative array. It can't fail. 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. + 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. + 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. + 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. + 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. + The caller should lock exclusively against other modifiers of the array. 3. Delete an object from an associative array:: @@ -206,15 +206,15 @@ The caller should lock exclusively against other modifiers of the array. const struct assoc_array_ops *ops, const void *index_key); -This deletes an object that matches the specified data from the array. + 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. + 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. + 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. @@ -225,14 +225,14 @@ The caller should lock exclusively against other modifiers of the array. 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 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. + 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. + The caller should lock exclusively against other modifiers of the array. 5. Destroy an associative array, deleting all objects:: @@ -240,14 +240,14 @@ The caller should lock exclusively against other modifiers of the array. 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. + 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. + The caller should lock exclusively against other modifiers and accessors + of the array. 6. Garbage collect an associative array:: @@ -257,24 +257,24 @@ of the array. 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. + 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 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 ``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. + 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. + 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 @@ -289,19 +289,19 @@ There are two functions for accessing an associative array: 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 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. + 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. + 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:: @@ -310,14 +310,15 @@ return. 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 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. + 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. + 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 |