From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68052C7EE22 for ; Wed, 10 May 2023 19:01:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232464AbjEJTBO (ORCPT ); Wed, 10 May 2023 15:01:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229555AbjEJTBK (ORCPT ); Wed, 10 May 2023 15:01:10 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3807BE for ; Wed, 10 May 2023 12:01:07 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1683745266; h=from:from:reply-to:subject:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=6VeszvmJNUYN70+RK5o7CAMFbLfrPw5Wbv+HBHpQnkU=; b=0uDoQAlU2tDjTgPPhnww90lqnbNn10piVW/W+bhmeFD0p0eFsCkFbE1F24H0kwpyXE+0jh 6IdPqRkAYhKMjvoXq6/ZET/uLN/UdACiQvi0O88dfwfPkkVJRf4wXw8FhQIM91l19nnHR8 vS1UmxQU4H3zQI+QkivQhBv7j0Pu4Laq3klS7W4TV51l2Hjor3QwH9fZ7nwae2cWrA1vQA Y4qZelXEvuNUUo6eUR4Jk7c36bke4rCzwgBgLeAeamu1hjBvqhzHVmPyoaXLzOjMXZccCW ZldaUA0RNQeNouHF5+uT36i0X+GLwHBg3K5KPq2AbOUFmw/1tp09c2djAbnZgg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1683745266; h=from:from:reply-to:subject:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=6VeszvmJNUYN70+RK5o7CAMFbLfrPw5Wbv+HBHpQnkU=; b=bQzJF2B85H2QAG7r3taZgh09YXEtuzcYWaVeD/EnJAeFpd7nYPHKacHxt6nF1HDZAAdBQC qOMX2x0nqFw3DuDQ== To: LKML Cc: "Liam R. Howlett" , Matthew Wilcox , linux-mm@kvack.org, Shanker Donthineni Subject: [PATCH] maple_tree: Fix a few documentation issues Subject: Date: Wed, 10 May 2023 21:01:05 +0200 Message-ID: <87mt2cxb7y.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The documentation of mt_next() claims that it starts the search at the provided index. That's incorrect as it starts the search after the provided index. The documentation of mt_find() is slightly confusing. "Handles locking" is not really helpful as it does not explain how the "locking" works. Also the documentation of index talks about a range, while in reality the index is updated on a succesful search to the index of the found entry plus one. Fix similar issues for mt_find_after() and mt_prev(). Remove the completely confusing and pointless "Note: Will not return the zero entry." comment from mt_for_each() and document @__index correctly. Signed-off-by: Thomas Gleixner --- include/linux/maple_tree.h | 4 +--- lib/maple_tree.c | 23 ++++++++++++++++++----- 2 files changed, 19 insertions(+), 8 deletions(-) --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -659,10 +659,8 @@ void *mt_next(struct maple_tree *mt, uns * mt_for_each - Iterate over each entry starting at index until max. * @__tree: The Maple Tree * @__entry: The current entry - * @__index: The index to update to track the location in the tree + * @__index: The index to start the search from. Subsequently used as iterator. * @__max: The maximum limit for @index - * - * Note: Will not return the zero entry. */ #define mt_for_each(__tree, __entry, __index, __max) \ for (__entry = mt_find(__tree, &(__index), __max); \ --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -5947,7 +5947,10 @@ EXPORT_SYMBOL_GPL(mas_next); * @index: The start index * @max: The maximum index to check * - * Return: The entry at @index or higher, or %NULL if nothing is found. + * Takes RCU read lock internally to protect the search, which does not + * protect the returned pointer after dropping RCU read lock. + * + * Return: The entry higher than @index or %NULL if nothing is found. */ void *mt_next(struct maple_tree *mt, unsigned long index, unsigned long max) { @@ -6012,7 +6015,10 @@ EXPORT_SYMBOL_GPL(mas_prev); * @index: The start index * @min: The minimum index to check * - * Return: The entry at @index or lower, or %NULL if nothing is found. + * Takes RCU read lock internally to protect the search, which does not + * protect the returned pointer after dropping RCU read lock. + * + * Return: The entry before @index or %NULL if nothing is found. */ void *mt_prev(struct maple_tree *mt, unsigned long index, unsigned long min) { @@ -6487,9 +6493,14 @@ EXPORT_SYMBOL(mtree_destroy); * mt_find() - Search from the start up until an entry is found. * @mt: The maple tree * @index: Pointer which contains the start location of the search - * @max: The maximum value to check + * @max: The maximum value of the search range + * + * Takes RCU read lock internally to protect the search, which does not + * protect the returned pointer after dropping RCU read lock. * - * Handles locking. @index will be incremented to one beyond the range. + * In case that an entry is found @index contains the index of the found + * entry plus one, so it can be used as iterator index to find the next + * entry. * * Return: The entry at or after the @index or %NULL */ @@ -6548,7 +6559,9 @@ EXPORT_SYMBOL(mt_find); * @index: Pointer which contains the start location of the search * @max: The maximum value to check * - * Handles locking, detects wrapping on index == 0 + * Same as mt_find() except that it checks @index for 0 before + * searching. If @index == 0, the search is aborted. This covers a wrap + * around of @index to 0 in an iterator loop. * * Return: The entry at or after the @index or %NULL */