From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout12.his.huawei.com (frasgout12.his.huawei.com [14.137.139.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 961FC14B07E; Wed, 25 Sep 2024 10:12:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=14.137.139.154 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727259145; cv=none; b=iWRJ6eoGLw09KcInkQuK9GqUVw9ywbYgNVyvPDG8qFnHWs9frIpgFUboLKBOtfRyX94xR8ma/R0loYr28gcBjoxk2cQYGkVbAY+IwXscT37IUzajXnFfysj0ZDwb8bctBv/mAffTg0m82Y4A7+4UgTiu8ZgQh1oL28g8uWUhgpI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727259145; c=relaxed/simple; bh=WNay2WNLiI/AIMNDpXFtNDMsDbvMSivFO34397OI6C4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=j02Nj0H7LKcAsvcu/KSJQCOQXrDKLinHtfJQNtMaAmUZixpjrUQ0+6+aEZN19mlZehfbiNKrpfDbl6sFZWktEARtXADMrayvG6Y6N1xbMW0wUgxQL7LnVHSJUdAgFys8KcRlX6fbsqXSuAHJkrriCOYJqrP2whl7G+UDZmbpLvU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=14.137.139.154 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.18.186.29]) by frasgout12.his.huawei.com (SkyGuard) with ESMTP id 4XDBhN6gTSz9v7JY; Wed, 25 Sep 2024 17:46:44 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.47]) by mail.maildlp.com (Postfix) with ESMTP id 99AD81404C6; Wed, 25 Sep 2024 18:12:10 +0800 (CST) Received: from [10.45.145.58] (unknown [10.45.145.58]) by APP1 (Coremail) with SMTP id LxC2BwBn+C_r4fNmunSaAQ--.25388S2; Wed, 25 Sep 2024 11:12:10 +0100 (CET) Message-ID: Date: Wed, 25 Sep 2024 12:11:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/4] hazptr: Add initial implementation of hazard pointers To: Boqun Feng Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@vger.kernel.org, "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Mark Rutland , Thomas Gleixner , Kent Overstreet , Linus Torvalds , Vlastimil Babka , maged.michael@gmail.com, Neeraj Upadhyay References: <20240917143402.930114-1-boqun.feng@gmail.com> <20240917143402.930114-2-boqun.feng@gmail.com> <55975a55-302f-4c45-bfcc-192a8a1242e9@huaweicloud.com> From: Jonas Oberhauser In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID:LxC2BwBn+C_r4fNmunSaAQ--.25388S2 X-Coremail-Antispam: 1UD129KBjDUn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7v73 VFW2AGmfu7bjvjm3AaLaJ3UjIYCTnIWjp_UUUYa7kC6x804xWl14x267AKxVWrJVCq3wAF c2x0x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII 0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20xvE14v26r1j6r1xM28EF7xv wVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwA2z4x0Y4vEx4A2jsIE14v26r4j6F4UM28EF7 xvwVC2z280aVCY1x0267AKxVW8Jr0_Cr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8C rVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxV WUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lFIxGxcIEc7CjxVA2Y2ka 0xkIwI1l42xK82IYc2Ij64vIr41l4c8EcI0Ec7CjxVAaw2AFwI0_GFv_Wryl4I8I3I0E4I kC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWU WwC2zVAF1VAY17CE14v26r4a6rW5MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr 0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6xAIw20EY4v20xvaj40_ Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8Jr UvcSsGvfC2KfnxnUUI43ZEXa7IUbHa0PUUUUU== X-CM-SenderInfo: 5mrqt2oorev25kdx2v3u6k3tpzhluzxrxghudrp/ Am 9/25/2024 um 12:02 PM schrieb Boqun Feng: > Hi Jonas, > > Of > course, if we are really worried about compilers being too "smart" Ah, I see you know me better and better... > we can always do the comparison in asm code, then compilers don't know > anything of the equality between 'ptr' and 'head - head_offset'. Yes, but then a simple compiler barrier between the comparison and returning ptr would also do the trick, right? And maybe easier on the eyes. Have fun, jonas