From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id 2ifrBGJfCmnQ0yAAWB0awg (envelope-from ) for ; Tue, 04 Nov 2025 15:17:38 -0500 Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=lists.lttng.org header.i=@lists.lttng.org header.a=rsa-sha256 header.s=mx header.b=ZLHnhZcf; dkim=pass (2048-bit key; unprotected) header.d=lists.lttng.org header.i=@lists.lttng.org header.a=rsa-sha256 header.s=default header.b=TOOazs11; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id 035C11E0BC; Tue, 04 Nov 2025 15:17:38 -0500 (EST) X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-25) on simark.ca X-Spam-Level: X-Spam-Status: No, score=-0.1 required=5.0 tests=ARC_SIGNED,ARC_VALID,BAYES_00, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED,RCVD_IN_VALIDITY_RPBL_BLOCKED, RCVD_IN_VALIDITY_SAFE_BLOCKED autolearn=no autolearn_force=no version=4.0.1 Received: from m43-8.mailgun.net (m43-8.mailgun.net [69.72.43.8]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by simark.ca (Postfix) with UTF8SMTPS id 714191E04C for ; Tue, 04 Nov 2025 15:17:36 -0500 (EST) DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=lists.lttng.org; q=dns/txt; s=mx; t=1762287449; x=1762294649; h=Sender: Sender: Reply-To: From: From: List-Subscribe: List-Help: List-Post: List-Archive: List-Unsubscribe: List-Id: MIME-Version: Content-Transfer-Encoding: Content-Type: Subject: Subject: Cc: To: To: Date: Message-ID; bh=9HNOfikLJOGTo7hkLPmB9+B4GFyLkxXP85HqJ8oeaoY=; b=ZLHnhZcfGV6KV0ZPfrrEUyat3do5Gztjbm/oDa7Qk9hQk87Oj1Ca0uayRcvXEFdooIrC0S8ri7tC/CdMe5SkCV4uFPc9/s+jgv10prGND3auLYCFYs9FIRBPO3TWBQRKEDnv6wzDg9bPo4QSXigrCSMKtmFosezZjxr3Wt8kIUfdw0oNthdT+/ElOzJV7+a1qMJT8FMFwZsOYy6JTlCNgfP06YTmo2qSAg1a0OIV/Dt/vBiPKMGqKsXfNYoV9OBxyTeM11001UGVXxr5Ak2lkgQFdr9P2CRswKVti+wDtZLGhw80XVyLvUNRgVgAAC9fSfQcc0+p6AAEes4LqpB4Tg== X-Mailgun-Sid: WyJkOTk2OCIsInB1YmxpYy1pbmJveEBzaW1hcmsuY2EiLCI2MDIzMjMiXQ== Received: from lists.lttng.org (lists.lttng.org [158.69.130.29]) by d7b4a886ab4c19c48982b2a533d7a0d0b37347d7ad10c5d4c180af4a4093feec with SMTP id 690a5f58b702616c6c8db0ef (version=TLS1.3, cipher=TLS_AES_128_GCM_SHA256); Tue, 04 Nov 2025 20:17:28 GMT X-Mailgun-Sending-Ip: 69.72.43.8 ARC-Filter: OpenARC Filter v1.2.1 lists.lttng.org 4d1KWC5BTgz1qyQ ARC-Seal: i=2; d=lists.lttng.org; s=arc1; a=rsa-sha256; cv=fail; t=1762287448; b=LT+CpGKhSuShMf6bwEcmY9wqirbLNFB+fOhMpZs5BpDruKP5aueLJna1UbCMKIfIxqHX JddLuYrgc4UGUr/20EBJeSwfd1xm/NRAcUV6VkZAn9v6EeY+X2YX9vFJdz6b+7OQtgAhA nx9R0Boo97vDlbM1m1E+a/P+bdXSARtLN4TEn3C2A/ZED00QOdodqLThdgJLuacl0OQuq VTF7NInKJckYS/5oaekihWBVQYgONQpMpaOAicBg9s2l5JzROcZljkUrVa6bfHPG3xHxw O3XFwPWc5ma067zLz2cAVQVvHHa0RYfZ8Wi2+jOzeKePlkEL0EzFh6AQk7ouszCcqDA== ARC-Message-Signature: i=2; d=lists.lttng.org; s=arc1; a=rsa-sha256; c=relaxed/simple; t=1762287448; h=DKIM-Signature:Message-ID:Date:To:Subject:MIME-Version:From:From; bh=mjtTw2N5XTMSS/AuB2ACB0dEtH7PBjV/Ozy7SOBLYss=; b=gx53NpaBcRaMWXQdbHQfavvbfBHur4RNwsFbK4cyQmN3qsFyKnpwFy3DSFGK2ZMO7dIA HQUNhS7CBwpdXIaFcMWwbXLNYHRitI7oazQkf9OFgDXq9tZy7vH0m3p6OaJPMYQAARuk6 LsVSBfa9TnfGbdWZZC4ImWCSAM1CaakmgMqBYvzYHwbxXTJCyZR9p2ggzTTiWqmAaf29J 61n/08dxr1ZnUJEuqZ9Hd+EPcEfTiCzFYP0eJFvgUPbqhvM/IqnaiSjl55IUcopddnMab fmDky+yK2UFU8pR0IEGwk91XgKcPow9DI3hOSg/QetHRkjWqqfbaZ/izvvnhuelyfsw== ARC-Authentication-Results: i=2; lists.lttng.org; arc=fail smtp.remote-ip="::1" DKIM-Filter: OpenDKIM Filter v2.11.0 lists.lttng.org 4d1KWC5BTgz1qyQ DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1762287448; bh=mjtTw2N5XTMSS/AuB2ACB0dEtH7PBjV/Ozy7SOBLYss=; h=Date:To:Cc:Subject:List-Id:List-Unsubscribe:List-Archive: List-Post:List-Help:List-Subscribe:From:Reply-To:From; b=TOOazs1149IFJjxrrzCBhD077v7KurOjwe+20rbsRODHt7WIHnG4ckV48jOxR7lKV QLyVj3520ACBc7PKXzcTPTkIyugCoBGh07OuowySTl4zwJm4QdnmywNfNaEe6NThHg TmvJt+4y+QbFTdp2jGfwMueLIodNnplnvJYOXsFunje5rItclKt61A3mzbTtOFeWEl rHQw+VXMRqrbbfWmFpvXWsB35DwU1JJxYew5SFc8O9Pf0WdupF0RHvkWXqqVwtwYj2 ayLZ7JCsH1PmUo2OnjA1mAIQPQkbG+A76VYuxMm5aXUKAe4xqmS50eMpHdiOOJYfsu WXDDpTtadQLww== Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4d1KWC5BTgz1qyQ; Tue, 4 Nov 2025 15:17:27 -0500 (EST) ARC-Filter: OpenARC Filter v1.2.1 lists.lttng.org 4d1KWB35zKz1qSM DKIM-Filter: OpenDKIM Filter v2.11.0 lists.lttng.org 4d1KWB35zKz1qSM Received: from YT6PR01CU002.outbound.protection.outlook.com (mail-canadacentralazon11022110.outbound.protection.outlook.com [40.107.193.110]) by lists.lttng.org (Postfix) with ESMTPS id 4d1KWB35zKz1qSM for ; Tue, 4 Nov 2025 15:17:25 -0500 (EST) ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=ZhO/wZi2uR3qpMRpBhy88gGOzCTpw+Tg6+tzYDTG8wKlK+8xFgBjGGD5wK7nh/hE9y9Bf3WWDcvmKCnUQp2mGYPai+2Q8dgl9Q0In3uZ7HRYb5Q5tbke6BM12m4/NWlrsEwTnlBIBCviopr6t90EGP/pu4UhWyhtVtuP+rVpSFROgfYDvKzd+6cd+U3Q6bFGrKDuhvVfPZ2EJi2VcnQZmAjAE6aPBjLUjmEP/Gn8k1VtmpKpJUwEDSeVWhaUPHqyuEU0z2UI4ja7KYq/IZ2ERZauYmn6QbxOjlSNkrVPKt3bdz9bcdHa0RaXXVQotRjDaUt5wMxAZ+XTAd44R1TD0w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=9HNOfikLJOGTo7hkLPmB9+B4GFyLkxXP85HqJ8oeaoY=; b=ZVCWiQnCuynKV2PI2pFZYzdmZUiFJRVA3x/NQvyIB3SwkxJWljwJBJNBCrfwamK3EBmV+qUDfaGlkuLWjFD3AvyXZJ42QvuWr//1/f9z/dIq2ClcOGaECLGJiK1LXGzsDNk3/Jh6ULpkypUdKTQj6XEHj0quj6B18I7PtH+oklrOv/WjoZA7YqWw16gBY3D4+/zu8HzXYoKTk7kMhjEWgUIndkd4foPUijHU0xyX+CU33CU5wfRbPmW7IphM6cYAiBSfAZsTcN/5YDhCNLYyKRjK9exXfxhu8rdha8poXdK93NuQxBPQ6XY7/JQekovNl1ObRcGHuoAfuCWaQjJaKQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=efficios.com; dmarc=pass action=none header.from=efficios.com; dkim=pass header.d=efficios.com; arc=none Received: from YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) by YT2PPFEC9C76D91.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b08::49f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9298.7; Tue, 4 Nov 2025 20:17:19 +0000 Received: from YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM ([fe80::50f1:2e3f:a5dd:5b4]) by YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM ([fe80::50f1:2e3f:a5dd:5b4%2]) with mapi id 15.20.9298.006; Tue, 4 Nov 2025 20:17:19 +0000 Message-ID: <43ad1f76-3682-47f4-b3c9-62a94053db3c@efficios.com> Date: Tue, 4 Nov 2025 15:17:17 -0500 User-Agent: Mozilla Thunderbird Content-Language: en-US To: linux-kernel@vger.kernel.org, lttng-dev@lists.lttng.org Cc: "Paul E. McKenney" , Alan Stern , Lai Jiangshan Subject: [RELEASE] Userspace RCU 0.15.4 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: YT4PR01CA0402.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:108::14) To YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:be::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: YT2PR01MB9175:EE_|YT2PPFEC9C76D91:EE_ X-MS-Office365-Filtering-Correlation-Id: 23d281a9-3adf-4f8a-08f2-08de1bdf277d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?Ty8yYXg0OGpkbmNxWEpNK2RFUVZ5Mmdia1FlYjlxVTRmUWNKZ2l1bUJCVlNM?= =?utf-8?B?RnMxV2t3ZEQwemkzckhHMTAyY0gvVzhlM2Fpay9EQkE1UTh5anpOQ0dUVHI4?= =?utf-8?B?dHhPcXJnR3NadHNkWEdZRHhTbWJycjA2REszSGsxQnJ2bS81KzRKbXpKdHZZ?= =?utf-8?B?UkZUY05JMUxOZERoSXJFeWpJRHYwejh6RUp2VWVVaHV5Q2tBc01TelNtTHZO?= =?utf-8?B?VUZJNGFnWkFzSDY2OUl0N013MlJiYThLMDc5dHA4SFNvVWtuSW8ybVR3R0tr?= =?utf-8?B?aXh2UnFNbENSQlVQU3NjRlJ2bDIvTUdUWVNvOVpwdk84MlVxVlFwck1PcG5i?= =?utf-8?B?S1FTSDRZdWROaXlYblZXU0ZGNmpIY3lzcERDOTUvcXJwcG1ZV1k0V0JWU0x3?= =?utf-8?B?NC9EeEJNeEFDT1Q5SmNudHdhY3FseGNTNUVQbUplV2VXRlg3WWNaWndWTVA5?= =?utf-8?B?TUxNQ0lvMnhNVUlLRkR3b2lwZ0NITENhbVI4VTFoQzd2eEM1dmhXeTQ2aC9Z?= =?utf-8?B?ZVIzeDlBbVdIQUFoMmlacmlpVVBwbTdObTJzTmJaSEdGYzFSVG1SMnFySjR3?= =?utf-8?B?ZHh0a1JzNXVZNFVyUUVkcW8zci9VaFI5dEVIKzdjcHF4eklManNndTYzQ2ti?= =?utf-8?B?RUEwV0hvbGF5aFpDV0l6NzZsVEFOMG5rSXhjNXEyejFDd2QrYVFtdEJCWmJv?= =?utf-8?B?VFZtUFh2aGZBeWxTbzNrR010dzdHbDAxNHJJR1RUMFhaWkR2cUszcHcxUjUr?= =?utf-8?B?SnJVU1FLUUVYVStGRTN2Wmt1OFY0Mm9yME1yODFmcU5tL2p6bTA3YitqK1ZG?= =?utf-8?B?eWZTQ2UvRVhMcmRqZ1hoOWdZT3pkWXdpQTg0ZFBJMU5wdm1pR25IRzlvOGdG?= =?utf-8?B?NGxmK21veEl4UlV6NHpzM2VycGo1MG1BV05VdDkyeUlRc2diV3krQ0p3ci9Z?= =?utf-8?B?YWVSZ0h1Q1FLbFNWYlRpWUY2dFVSMU1hV2lMd2JsMUF0Y0c3WlFURzIvNGw1?= =?utf-8?B?VFJtZnk5UDhYNjBHczVvYUJ4WnhZd0p6cmJ2SlcyVW4xdG5hbDRIVDY5TlZO?= =?utf-8?B?dERBTS82QVYyL3ZLdmc0NHNuU3oxaWJyOHdaNkJsRnJ1dDY4VmVCaGtydSto?= =?utf-8?B?enhlOGRhcXhGTWlnTllycVFJUG1MYnA5UmZDZmNRWjdGdHhBYzRmTFNhWE1x?= =?utf-8?B?RVJwNDRlNWJFVy9UNXV0NU5oZjBwOHZKY1QraTRNNHJOZ0NUS2dzZ3gyNkkx?= =?utf-8?B?NXpMV2I3aWxwS1Q5YytoMGxLVGJqQjMwUUNicGZSWGdBUUMwOGliV1RrOFVu?= =?utf-8?B?cmp1WFJ0Z2lSL3dqQnpETUdzTFpyZE56b2NmVWF5Nkdtd1dWZXZEWVYyc3VG?= =?utf-8?B?SlhYR05uK3ZETmxXSTNzTzR1VUY0V21YM29qWWxVZnk1ZkpKODNEOVNZVGsz?= =?utf-8?B?aEI2REE0UTduRE05VlgwcUVCY3BLbjNSVWJydXluemdFMVFyRDR0Q1YzZWRO?= =?utf-8?B?VENtTG9xejdBK2dFb3FZdVh3eTZDZE16anNMbklKOVZKRjJtTUVyMjNtajlK?= =?utf-8?B?TzhoTkJqbEdZOExLU2d4aWE3cGlCbEoza2J1bXBVZXBkcGpBV3RZZDdhYjFa?= =?utf-8?B?cE5adTN3UVhna1BhZ05obFBTcktrS1o2UWYvUXFocHNxU21PSGpzYkdXZ0tR?= =?utf-8?B?bS9wSjFiUm5jRDF1alZpdXNkOXNtNU9EMmc4NjFzRU1WYXp5N0VMcEp2R3FC?= =?utf-8?B?SktiMWI0Zkt6ZkZmMjhpZ0NBVmp6cDdhV2IxZmRCL3FEbkpqaS81RUt6VHRT?= =?utf-8?B?aE9sc0dTTXROekQzWE54a2wwUEFmN3REQWV4c2FySFJFZTQ1UnY2YUZSMm9u?= =?utf-8?B?SkNXSmJKdk05L1Z5YWVVT2pkM3VjR2FiMVBscUNld2JHTmc9PQ==?= X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM; PTR:; CAT:NONE; SFS:(13230040)(1800799024)(376014)(366016); DIR:OUT; SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?NERtU3V3WSsvSXhhZlMwQWRXZnZtZzJ6YXZwdXl0YkwrV3ptRHdYRjY0Y0xk?= =?utf-8?B?djlKQk9TNVkvYnNja0xDU2Y2cmlXby9IY2xFWk5MeEZ2anFsUE16eWt2MTM1?= =?utf-8?B?YmVrVUtlbFRkaGpheHJFOGpuSlZmVmMrelpQZDBZYnl3R0F6Y202VWtGYW44?= =?utf-8?B?TVNFbEJDZGwxNzJDRURiTlhnRFM5UGl6OGtybHJnenAyanpHT1FLUUJweFV2?= =?utf-8?B?b29ZTDc2dmJxdWxoMm9MYThoNk05T01qRVhDWXpYOGtPTUdsb1R0b0dmZnBs?= =?utf-8?B?Szh1TXkvMmU4RWUvYkJzWDlaRjI0QmNIRThWMHVQbUY0Yit5RDh2bGVhOVYw?= =?utf-8?B?cjhIWkx6MjF4enRQeTJqVTJUMjdmY2hvWEREQXYzQVJDN0h1RzBtbjl0ZUtQ?= =?utf-8?B?TzdEV2Zrd3FNZTJVZEVmZFRSTml1NG5yQjJpTHdSMWtDT1pSemJGZ0hsUEtY?= =?utf-8?B?M1hHRGRQRUVwaUN1Y2Z4M3dWdktvNTZ5SVAwTzdDd2R6aTBnWW5ZSVlVaVBF?= =?utf-8?B?ZkNPRmU0MWdPNnhmYm1uNytCOWU5bUtQNFphbGluOWhwQmJZMG5VdTA4dlFq?= =?utf-8?B?UEZoNnBjMVFGUUZmZ2hmSzFMNkVvSGdncnQ0eEVXVGIwQ2QrMFF5WEJRR1ZN?= =?utf-8?B?QkNHMDcyR2NwZVBhTTJWZVlXd3dKck93akxLRjBiUG9waUxLcHlONG1GQVgy?= =?utf-8?B?T2M2YnZuMkdVc1pEQ1RsZHpkd2RTYjNWMWJlN2NGR3ZDK2xrSWZsV0E3T3FP?= =?utf-8?B?cDYzQWNpMTc4bkFHUnJzYWx1b2pmbE1wMnBFZ1BwdjJQRkZyQ0E3S21wRWMy?= =?utf-8?B?blZ3WjM2eGZENC80Yk9EM1IwaSs2TFZtYngrbDFSNXJLbERuUmg5cm4walVr?= =?utf-8?B?TGVhRHZBYVpFZnU2eUN3b2duUHBucjJPSXFydlBGdThNaytIeFAzZ2h0cFN0?= =?utf-8?B?NHBpNWlyVWNrSDczeEhmSmIyZkpYa1M2Tzl6ZDdhcEVoWjh4dW9nbjEyTXk0?= =?utf-8?B?OUY5TkpEcllocHJpMDI1QVQ5RGMwWGJneTg0QTJDVkpNSU0zTkgyKzIwVVZW?= =?utf-8?B?WnhqZjRPTW5mS3ZDMk9aQUp4ZVk4Z0NRQVZnZWhJaUwrOERzSG9QTDdBQzRi?= =?utf-8?B?RkZMQ0VubkJVRGpWdUt4RXFrL1pjelFwRmtnRHViT213bmg3UUFmS21jeXFW?= =?utf-8?B?cDFjQ0ZjNC9uNkNjcHYzNjIwYStvOTNFOGplTHM2aGZCZWtQemdPc1g0Zis3?= =?utf-8?B?QmJrOEJWNUttNTBuejlOSHdkbVM5NEp4ekhkRWlYLzJHRnBZTWdQdnlWZUt2?= =?utf-8?B?dFFUNVZhYTI3RTh2Qjh3SElpMnMzLzZ5L0NMTEhIajVwT2JCRlY4cm0zYlJH?= =?utf-8?B?OGhvV2dUdmlZNjdQQUVrRDhURERvWmxYdmVyQjRDcllWM1dZQ0VUZ0tyQkts?= =?utf-8?B?WUdMTGgzaFA4aktWNE1TOGl6K2hpNm0wZmQrbVpvT3RCS0t1VDdsMzBQUVNn?= =?utf-8?B?ZFFnMDVCRXZqekNKSVdFUkExbDBGWER4Nm5mUDFPWWF5bWhEc2FjU0ZKa0VF?= =?utf-8?B?dk5oVHo5NEVhN1BkcDJDbUw3MWZZSXdEZDlqNkxBS1BQenhCejlINCtDU05h?= =?utf-8?B?M3NZUkVRVWdscVowSVgybWQrb2t3dlZUSVBUZWM0MStDcXVteGJsUXpLanlo?= =?utf-8?B?MDZZdGszZlFxMmVIY0JjMkFtTzZkTzFqVE5zYlRpaVhtd2tMY081aXBZRkdk?= =?utf-8?B?dWpRT25JODVFNVF4VW1UV1ZBUXBQaUpSVWh2MXpsZFRJalJHcXZTaExoUGlk?= =?utf-8?B?aWZPcGExMWJDM3F5SGhVQTR3QVJheFlmVHlwNVhjTzFURHk1Vm90aHZWS2lS?= =?utf-8?B?T3d4ZmdTMmYwR2paYjVnZko4cWl5UTcwSGRndHJ3c2l1M1dxT0RHTExOVDJI?= =?utf-8?B?bUJWS1k0Rkt3Zkg4RnRPVVVjU1prWkhVb2U2SkNsVHVXazZyL0hiWTRCSUV6?= =?utf-8?B?OE1iVHFveWVUVmlzQ3J0bW1sZE5IQUdUTGIzbUJLaW81clBLZGVQckJJOXZ0?= =?utf-8?B?eG9SRGZUZXpuU0cxVXZ6VDdMcnAzR3NCS3pOOVYvTG9BVXJNRytIOTRLZlln?= =?utf-8?B?WUFZUW41cEx0aXhaNnBVRUpYWVlRcTFVbS8vZE5Takp0YjJkdnQ4V0tJVGxr?= =?utf-8?Q?adF62zWW1J0RQuLvbPkxaAY=3D?= X-OriginatorOrg: efficios.com X-MS-Exchange-CrossTenant-Network-Message-Id: 23d281a9-3adf-4f8a-08f2-08de1bdf277d X-MS-Exchange-CrossTenant-AuthSource: YT2PR01MB9175.CANPRD01.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Nov 2025 20:17:18.8877 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4f278736-4ab6-415c-957e-1f55336bd31e X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: RqTP4W2aE0HjjbSkMjz2PZ16HFaLf0numu+e4d9OI1z04GwyUS0IAiqxsSty3cox2TYiKubfH6yWQKysroXl9UQb4nAxt24qYDp6aI+/tvQ= X-MS-Exchange-Transport-CrossTenantHeadersStamped: YT2PPFEC9C76D91 X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Mathieu Desnoyers via lttng-dev Reply-To: Mathieu Desnoyers Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" Hi, This is a patchlevel release of the Userspace RCU library. The most relevant change in this release is the removal of a redundant memory barrier on x86 for store and RMW operations with the CMM_SEQ_CST_FENCE memory ordering. This addresses a performance regression for users of the pre-0.15 uatomic API that build against a liburcu configured to use compiler builtins for atomics (--enable-compiler-atomic-builtins). As a reminder, the CMM_SEQ_CST_FENCE MO is a superset of SEQ_CST: it provides sequential consistency _and_ acts as a full memory barrier, similarly to the semantic associated with cmpxchg() and atomic_add_return() within the LKMM. Here is the rationale for this change: /* * On x86, a atomic store with sequential consistency is always implemented with * an exchange operation, which has an implicit lock prefix when a memory operand * is used. * * Indeed, on x86, only loads can be re-ordered with prior stores. Therefore, * for keeping sequential consistency, either load operations or store * operations need to have a memory barrier. All major toolchains have selected * the store operations to have this barrier to avoid penalty on load * operations. * * Therefore, assuming that the used toolchain follows this convention, it is * safe to rely on this implicit memory barrier to implement the * `CMM_SEQ_CST_FENCE` memory order and thus no further barrier need to be * emitted. */ #define cmm_seq_cst_fence_after_atomic_store(...) \ do { } while (0) /* * Let the default implementation (emit a memory barrier) after load operations * for the `CMM_SEQ_CST_FENCE`. The rationale is explained above for * `cmm_seq_cst_fence_after_atomic_store()`. */ /* #define cmm_seq_cst_fence_after_atomic_load(...) */ /* * On x86, atomic read-modify-write operations always have a lock prefix either * implicitly or explicitly for sequential consistency. * * Therefore, no further memory barrier, for the `CMM_SEQ_CST_FENCE` memory * order, needs to be emitted for these operations. */ #define cmm_seq_cst_fence_after_atomic_rmw(...) \ do { } while (0) Changelog: 2025-11-04 Userspace RCU 0.15.4 * uatomic: Fix redundant memory barriers for atomic builtin operations * Cleanup: Remove useless declarations from urcu-qsbr * src/urcu-bp.c: assert => urcu_posix_assert * ppc.h: improve ppc64 caa_get_cycles on Darwin Thanks, Mathieu Project website: https://liburcu.org Git repository: https://git.liburcu.org/userspace-rcu.git -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com