- Replace "they" with "you" where "you" is used in the preceding sentence fragment. - Mention `xa_erase` in discussion of multi-index entries. Split this into a separate sentence. - Add "call" parentheses on "xa_store" for consistency and linkification. - Add caveat that `xa_store` and `xa_erase` are not equivalent in the presence of `XA_FLAGS_ALLOC`. Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Reviewed-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx> Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxx> --- Changes in v5: - Add trailers; otherwise resend of v4. Sent as v5 due to tooling issue. - Link to v4: https://lore.kernel.org/r/20241010214150.52895-2-tamird@xxxxxxxxx/ Changes in v4: - Remove latent sentence fragment. Changes in v3: - metion `xa_erase`/`xa_store(NULL)` in multi-index entry discussion. - mention non-equivalent of `xa_erase`/`xa_store(NULL)` in the presence of `XA_FLAGS_ALLOC`. Changes in v2: - s/use/you/ (Darrick J. Wong) --- Documentation/core-api/xarray.rst | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst index 77e0ece2b1d6f8e632e7d28d17fd1c60fcf0b5c4..f6a3eef4fe7f0a84068048175cb857d566f63516 100644 --- a/Documentation/core-api/xarray.rst +++ b/Documentation/core-api/xarray.rst @@ -42,8 +42,8 @@ call xa_tag_pointer() to create an entry with a tag, xa_untag_pointer() to turn a tagged entry back into an untagged pointer and xa_pointer_tag() to retrieve the tag of an entry. Tagged pointers use the same bits that are used to distinguish value entries from normal pointers, so you must -decide whether they want to store value entries or tagged pointers in -any particular XArray. +decide whether you want to store value entries or tagged pointers in any +particular XArray. The XArray does not support storing IS_ERR() pointers as some conflict with value entries or internal entries. @@ -52,8 +52,9 @@ An unusual feature of the XArray is the ability to create entries which occupy a range of indices. Once stored to, looking up any index in the range will return the same entry as looking up any other index in the range. Storing to any index will store to all of them. Multi-index -entries can be explicitly split into smaller entries, or storing ``NULL`` -into any entry will cause the XArray to forget about the range. +entries can be explicitly split into smaller entries. Unsetting (using +xa_erase() or xa_store() with ``NULL``) any entry will cause the XArray +to forget about the range. Normal API ========== @@ -63,13 +64,14 @@ for statically allocated XArrays or xa_init() for dynamically allocated ones. A freshly-initialised XArray contains a ``NULL`` pointer at every index. -You can then set entries using xa_store() and get entries -using xa_load(). xa_store will overwrite any entry with the -new entry and return the previous entry stored at that index. You can -use xa_erase() instead of calling xa_store() with a -``NULL`` entry. There is no difference between an entry that has never -been stored to, one that has been erased and one that has most recently -had ``NULL`` stored to it. +You can then set entries using xa_store() and get entries using +xa_load(). xa_store() will overwrite any entry with the new entry and +return the previous entry stored at that index. You can unset entries +using xa_erase() or by setting the entry to ``NULL`` using xa_store(). +There is no difference between an entry that has never been stored to +and one that has been erased with xa_erase(); an entry that has most +recently had ``NULL`` stored to it is also equivalent except if the +XArray was initialized with ``XA_FLAGS_ALLOC``. You can conditionally replace an entry at an index by using xa_cmpxchg(). Like cmpxchg(), it will only succeed if --- base-commit: 850925a8133c73c4a2453c360b2c3beb3bab67c9 change-id: 20241026-xarray-documentation-86e1f2d047db Best regards, -----BEGIN SSH SIGNATURE----- U1NIU0lHAAAAAQAAADMAAAALc3NoLWVkMjU1MTkAAAAgtYz36g7iDMSkY5K7Ab51ksGX7h JgsMRt+XVZTrIzMVIAAAADZ2l0AAAAAAAAAAZzaGE1MTIAAABTAAAAC3NzaC1lZDI1NTE5 AAAAQC+xZK2BwwOe02PlxGG7H8RrxZYY51gb8CdxLI3ED8WXT/GVeL/Ya7k+bir1TUuu/A pWBj+lROjke/NRDPTiJAQ= -----END SSH SIGNATURE----- -- Tamir Duberstein <tamird@xxxxxxxxx>
