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 92ECCC4332F for ; Mon, 7 Nov 2022 00:01:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230158AbiKGABt (ORCPT ); Sun, 6 Nov 2022 19:01:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230150AbiKGABo (ORCPT ); Sun, 6 Nov 2022 19:01:44 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1621ED135 for ; Sun, 6 Nov 2022 16:01:43 -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 dfw.source.kernel.org (Postfix) with ESMTPS id A31DB60E07 for ; Mon, 7 Nov 2022 00:01:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04A4EC433D6; Mon, 7 Nov 2022 00:01:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1667779302; bh=+HnWi0eHo5KFgV41jQmmg9tq0Bty7TKA39CYfWE8G3M=; h=Date:To:From:Subject:From; b=iUq5Gjo+Cldsz70GOglx3WhSe3M9gsaQ+VDhZLA4HOT4H5gCK7hfVztwfKBP3a1gm S4mBhUT9TGBlqpGcDhRAHHwyKCkStQiTze7Xj1MIV85KiiV1V3iLroz3LnVN8HjuRq TUeXK0ItAoi7Hmxfp6bLcKSJXT2BO5KF3U7uZ0PA= Date: Sun, 06 Nov 2022 16:01:41 -0800 To: mm-commits@vger.kernel.org, sander@svanheule.net, rostedt@goodmis.org, peterz@infradead.org, naveen.n.rao@linux.ibm.com, mhiramat@kernel.org, jpoimboe@kernel.org, ebiggers@google.com, davem@davemloft.net, dan.j.williams@intel.com, anil.s.keshavamurthy@intel.com, wuqiang.matt@bytedance.com, akpm@linux-foundation.org From: Andrew Morton Subject: + kprobes-freelisth-removed.patch added to mm-nonmm-unstable branch Message-Id: <20221107000142.04A4EC433D6@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: kprobes: freelist.h removed has been added to the -mm mm-nonmm-unstable branch. Its filename is kprobes-freelisth-removed.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kprobes-freelisth-removed.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: wuqiang Subject: kprobes: freelist.h removed Date: Sun, 6 Nov 2022 13:34:41 +0800 This patch will remove freelist.h from kernel source tree, since the only use cases (kretprobe and rethook) are converted to objpool. Link: https://lkml.kernel.org/r/20221106053441.103199-5-wuqiang.matt@bytedance.com Signed-off-by: wuqiang Cc: Anil S Keshavamurthy Cc: Dan Williams Cc: David S. Miller Cc: Eric Biggers Cc: Josh Poimboeuf Cc: Masami Hiramatsu (Google) Cc: "Naveen N. Rao" Cc: Peter Zijlstra Cc: Sander Vanheule Cc: Steven Rostedt (VMware) Signed-off-by: Andrew Morton --- include/linux/freelist.h | 129 ------------------------------------- 1 file changed, 129 deletions(-) --- a/include/linux/freelist.h +++ /dev/null @@ -1,129 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause */ -#ifndef FREELIST_H -#define FREELIST_H - -#include - -/* - * Copyright: cameron@moodycamel.com - * - * A simple CAS-based lock-free free list. Not the fastest thing in the world - * under heavy contention, but simple and correct (assuming nodes are never - * freed until after the free list is destroyed), and fairly speedy under low - * contention. - * - * Adapted from: https://moodycamel.com/blog/2014/solving-the-aba-problem-for-lock-free-free-lists - */ - -struct freelist_node { - atomic_t refs; - struct freelist_node *next; -}; - -struct freelist_head { - struct freelist_node *head; -}; - -#define REFS_ON_FREELIST 0x80000000 -#define REFS_MASK 0x7FFFFFFF - -static inline void __freelist_add(struct freelist_node *node, struct freelist_head *list) -{ - /* - * Since the refcount is zero, and nobody can increase it once it's - * zero (except us, and we run only one copy of this method per node at - * a time, i.e. the single thread case), then we know we can safely - * change the next pointer of the node; however, once the refcount is - * back above zero, then other threads could increase it (happens under - * heavy contention, when the refcount goes to zero in between a load - * and a refcount increment of a node in try_get, then back up to - * something non-zero, then the refcount increment is done by the other - * thread) -- so if the CAS to add the node to the actual list fails, - * decrese the refcount and leave the add operation to the next thread - * who puts the refcount back to zero (which could be us, hence the - * loop). - */ - struct freelist_node *head = READ_ONCE(list->head); - - for (;;) { - WRITE_ONCE(node->next, head); - atomic_set_release(&node->refs, 1); - - if (!try_cmpxchg_release(&list->head, &head, node)) { - /* - * Hmm, the add failed, but we can only try again when - * the refcount goes back to zero. - */ - if (atomic_fetch_add_release(REFS_ON_FREELIST - 1, &node->refs) == 1) - continue; - } - return; - } -} - -static inline void freelist_add(struct freelist_node *node, struct freelist_head *list) -{ - /* - * We know that the should-be-on-freelist bit is 0 at this point, so - * it's safe to set it using a fetch_add. - */ - if (!atomic_fetch_add_release(REFS_ON_FREELIST, &node->refs)) { - /* - * Oh look! We were the last ones referencing this node, and we - * know we want to add it to the free list, so let's do it! - */ - __freelist_add(node, list); - } -} - -static inline struct freelist_node *freelist_try_get(struct freelist_head *list) -{ - struct freelist_node *prev, *next, *head = smp_load_acquire(&list->head); - unsigned int refs; - - while (head) { - prev = head; - refs = atomic_read(&head->refs); - if ((refs & REFS_MASK) == 0 || - !atomic_try_cmpxchg_acquire(&head->refs, &refs, refs+1)) { - head = smp_load_acquire(&list->head); - continue; - } - - /* - * Good, reference count has been incremented (it wasn't at - * zero), which means we can read the next and not worry about - * it changing between now and the time we do the CAS. - */ - next = READ_ONCE(head->next); - if (try_cmpxchg_acquire(&list->head, &head, next)) { - /* - * Yay, got the node. This means it was on the list, - * which means should-be-on-freelist must be false no - * matter the refcount (because nobody else knows it's - * been taken off yet, it can't have been put back on). - */ - WARN_ON_ONCE(atomic_read(&head->refs) & REFS_ON_FREELIST); - - /* - * Decrease refcount twice, once for our ref, and once - * for the list's ref. - */ - atomic_fetch_add(-2, &head->refs); - - return head; - } - - /* - * OK, the head must have changed on us, but we still need to decrement - * the refcount we increased. - */ - refs = atomic_fetch_add(-1, &prev->refs); - if (refs == REFS_ON_FREELIST + 1) - __freelist_add(prev, list); - } - - return NULL; -} - -#endif /* FREELIST_H */ _ Patches currently in -mm which might be from wuqiang.matt@bytedance.com are lib-objpool-added-ring-array-based-lockless-mpmc-queue.patch lib-objpool-test-module-added.patch kprobes-kretprobe-scalability-improvement-with-objpool.patch kprobes-freelisth-removed.patch kprobeslib-kretprobe-scalability-improvement.patch