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 DC5AAECAAD5 for ; Mon, 12 Sep 2022 04:57:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229721AbiILE5L (ORCPT ); Mon, 12 Sep 2022 00:57:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54616 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229642AbiILE44 (ORCPT ); Mon, 12 Sep 2022 00:56:56 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28B6427FFD for ; Sun, 11 Sep 2022 21:56:40 -0700 (PDT) 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 D0D09B80C74 for ; Mon, 12 Sep 2022 04:56:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78804C433D7; Mon, 12 Sep 2022 04:56:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1662958597; bh=Gy3w9jzgIjBDk2+mJiQ/m18J3gMqT5V3YF5Fmics+j8=; h=Date:To:From:Subject:From; b=HAGHUZy5o5E/m2smbXKQVBzMTECTIwZ9/UomNB6jr3QZaxxxkSb5k4DDI/Db3sgH4 59ukPI0ItHogqOidLtgCnxjKKumCEzbPL53TIqWEZDarmmT5dIjXD9k35MFiwUSWKE Xl2U4S6lmTG5CBCAKxC2PkRbk/PUu4n1GYlKlNso= Date: Sun, 11 Sep 2022 21:56:36 -0700 To: mm-commits@vger.kernel.org, ubizjak@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-nonmm-stable] iversion-use-atomic64_try_cmpxchg.patch removed from -mm tree Message-Id: <20220912045637.78804C433D7@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: iversion: use atomic64_try_cmpxchg) has been removed from the -mm tree. Its filename was iversion-use-atomic64_try_cmpxchg.patch This patch was dropped because it was merged into the mm-nonmm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Uros Bizjak Subject: iversion: use atomic64_try_cmpxchg) Date: Sun, 21 Aug 2022 21:30:11 +0200 Use atomic64_try_cmpxchg instead of atomic64_cmpxchg (*ptr, old, new) == old in inode_set_max_iversion_raw, inode_maybe_inc_version and inode_query_iversion. 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, enabling further code simplifications. The loop in inode_maybe_inc_iversion improves from: 5563: 48 89 ca mov %rcx,%rdx 5566: 48 89 c8 mov %rcx,%rax 5569: 48 83 e2 fe and $0xfffffffffffffffe,%rdx 556d: 48 83 c2 02 add $0x2,%rdx 5571: f0 48 0f b1 16 lock cmpxchg %rdx,(%rsi) 5576: 48 39 c1 cmp %rax,%rcx 5579: 0f 84 85 fc ff ff je 5204 <...> 557f: 48 89 c1 mov %rax,%rcx 5582: eb df jmp 5563 <...> to: 5563: 48 89 c2 mov %rax,%rdx 5566: 48 83 e2 fe and $0xfffffffffffffffe,%rdx 556a: 48 83 c2 02 add $0x2,%rdx 556e: f0 48 0f b1 11 lock cmpxchg %rdx,(%rcx) 5573: 0f 84 8b fc ff ff je 5204 <...> 5579: eb e8 jmp 5563 <...> Link: https://lkml.kernel.org/r/20220821193011.88208-1-ubizjak@gmail.com Signed-off-by: Uros Bizjak Signed-off-by: Andrew Morton --- include/linux/iversion.h | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-) --- a/include/linux/iversion.h~iversion-use-atomic64_try_cmpxchg +++ a/include/linux/iversion.h @@ -123,17 +123,12 @@ inode_peek_iversion_raw(const struct ino static inline void inode_set_max_iversion_raw(struct inode *inode, u64 val) { - u64 cur, old; + u64 cur = inode_peek_iversion_raw(inode); - cur = inode_peek_iversion_raw(inode); - for (;;) { + do { if (cur > val) break; - old = atomic64_cmpxchg(&inode->i_version, cur, val); - if (likely(old == cur)) - break; - cur = old; - } + } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, val)); } /** @@ -197,7 +192,7 @@ inode_set_iversion_queried(struct inode static inline bool inode_maybe_inc_iversion(struct inode *inode, bool force) { - u64 cur, old, new; + u64 cur, new; /* * The i_version field is not strictly ordered with any other inode @@ -211,19 +206,14 @@ inode_maybe_inc_iversion(struct inode *i */ smp_mb(); cur = inode_peek_iversion_raw(inode); - for (;;) { + do { /* If flag is clear then we needn't do anything */ if (!force && !(cur & I_VERSION_QUERIED)) return false; /* Since lowest bit is flag, add 2 to avoid it */ new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT; - - old = atomic64_cmpxchg(&inode->i_version, cur, new); - if (likely(old == cur)) - break; - cur = old; - } + } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); return true; } @@ -304,10 +294,10 @@ inode_peek_iversion(const struct inode * static inline u64 inode_query_iversion(struct inode *inode) { - u64 cur, old, new; + u64 cur, new; cur = inode_peek_iversion_raw(inode); - for (;;) { + do { /* If flag is already set, then no need to swap */ if (cur & I_VERSION_QUERIED) { /* @@ -320,11 +310,7 @@ inode_query_iversion(struct inode *inode } new = cur | I_VERSION_QUERIED; - old = atomic64_cmpxchg(&inode->i_version, cur, new); - if (likely(old == cur)) - break; - cur = old; - } + } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); return cur >> I_VERSION_QUERIED_SHIFT; } _ Patches currently in -mm which might be from ubizjak@gmail.com are