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 1DDB4C54E94 for ; Tue, 24 Jan 2023 21:22:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234844AbjAXVW0 (ORCPT ); Tue, 24 Jan 2023 16:22:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234895AbjAXVWZ (ORCPT ); Tue, 24 Jan 2023 16:22:25 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0D8F3A8C for ; Tue, 24 Jan 2023 13:22:24 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9CED9B81711 for ; Tue, 24 Jan 2023 21:22:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F025C433EF; Tue, 24 Jan 2023 21:22:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1674595342; bh=TcolPVoAQADgNgA5iMovUCSDT8fT4FvIdK73++gbfYM=; h=Date:To:From:Subject:From; b=t8e0uSyjB6RIkLl+cqDrhFtBX45f9yLXfSV31/XRnwPw2f+QHJADAp880VuCO6DfB wMOR44mXcRGTu8e7iMH/9Eac0m59GemlCBCMTWls+G9xLS3UkZPDVBzFDAmUkFsedf eC2K8AmA+nsbNMx++JCNpEwbLcM1VY623/GbBTOk= Date: Tue, 24 Jan 2023 13:22:21 -0800 To: mm-commits@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, ubizjak@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + fs-ext4-use-try_cmpxchg-in-ext4_update_bh_state.patch added to mm-nonmm-unstable branch Message-Id: <20230124212222.3F025C433EF@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: fs/ext4: use try_cmpxchg in ext4_update_bh_state has been added to the -mm mm-nonmm-unstable branch. Its filename is fs-ext4-use-try_cmpxchg-in-ext4_update_bh_state.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-ext4-use-try_cmpxchg-in-ext4_update_bh_state.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Uros Bizjak Subject: fs/ext4: use try_cmpxchg in ext4_update_bh_state Date: Wed, 2 Nov 2022 08:11:47 +0100 Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in ext4_update_bh_state. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, try_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails. There is no need to re-read the value in the loop. No functional change intended. Link: https://lkml.kernel.org/r/20221102071147.6642-1-ubizjak@gmail.com Signed-off-by: Uros Bizjak Cc: "Theodore Ts'o" Cc: Andreas Dilger Signed-off-by: Andrew Morton --- fs/ext4/inode.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/fs/ext4/inode.c~fs-ext4-use-try_cmpxchg-in-ext4_update_bh_state +++ a/fs/ext4/inode.c @@ -786,11 +786,10 @@ static void ext4_update_bh_state(struct * once we get rid of using bh as a container for mapping information * to pass to / from get_block functions, this can go away. */ + old_state = READ_ONCE(bh->b_state); do { - old_state = READ_ONCE(bh->b_state); new_state = (old_state & ~EXT4_MAP_FLAGS) | flags; - } while (unlikely( - cmpxchg(&bh->b_state, old_state, new_state) != old_state)); + } while (unlikely(!try_cmpxchg(&bh->b_state, &old_state, new_state))); } static int _ext4_get_block(struct inode *inode, sector_t iblock, _ Patches currently in -mm which might be from ubizjak@gmail.com are lib-genalloc-use-try_cmpxchg-in-setclear_bits_ll.patch fs-ext4-use-try_cmpxchg-in-ext4_update_bh_state.patch