From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (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 499EA1D4146; Mon, 7 Oct 2024 13:24:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728307493; cv=none; b=VIFuo8Kixex4g5no+7ZojB32Tabf4LWw0dpne3RfskAGyHyZE6KxanqXLD+rqelL9EVJHhIuJ+wSq9/KFaVm2C3lZyZCLu6aYYrGfBHOAMNogOng5Ae1EXH4lz4qyGE4QbiFxm8f1nJKVhIaAcsxuOrPBRivL+S7SwrVmN0MOOM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728307493; c=relaxed/simple; bh=89Gasxm3AKnvBRytdU61zHDIonC6RjkNEXr4NpQ4woI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qNEEgsrnxBf5p6IAjt84glI0+W5VQ8t6HNzkYabGOMg1drX39H7tKOrEawvqKDKn9rm0f0EPvXWoHiqh7dRd1jUBGzJo8CgA3NIDEZIPX1Pl9y7uvsDwkh2ni5rvuyYYr2DVfZyGG2P/Av45B3GInnAWXFLKHs1qrlQ5c0hKF4k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=E4Y4UnxL; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="E4Y4UnxL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1728307491; bh=89Gasxm3AKnvBRytdU61zHDIonC6RjkNEXr4NpQ4woI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=E4Y4UnxLXftMgVjVchGlQ4dyZB24l3kfZeQVkEBpb/fNniUr2TSRYKkj6XXT8XH7A VMSAsAYcV5RxldzGzjwF1ck/6pVo16iS7Wnu0DuHID6gnYU2RI3CxCjWuTXQY5s9dr F6P6UbxL7fIF+1KJp9rXFcAYktrYRDQbT1wbJdGDpjnFnGKPg1XUEEO6BiwRiNCVk6 gvEqE1hZOJ+VByvzGHnPTncAUnw2Cf3IGcLy5lRXQcdgpJOTBtiFbJEHaXLMgeal0F RHoay27oMFkmzhTo748OUwCsXAhoRjw7ACGQPPAgLvN3clX6AmLedoB4CdjA+ooVeN qZGkbPyn4onbQ== Received: from [172.16.0.134] (96-127-217-162.qc.cable.ebox.net [96.127.217.162]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4XMfyV0wW3z2kv; Mon, 7 Oct 2024 09:24:50 -0400 (EDT) Message-ID: <812121c6-734d-4f68-b808-d3fa7c380604@efficios.com> Date: Mon, 7 Oct 2024 09:22:52 -0400 Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v2 3/4] hp: Implement Hazard Pointers To: Peter Zijlstra Cc: Boqun Feng , linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Nicholas Piggin , Michael Ellerman , Greg Kroah-Hartman , Sebastian Andrzej Siewior , "Paul E. McKenney" , Will Deacon , Alan Stern , John Stultz , Neeraj Upadhyay , Frederic Weisbecker , Joel Fernandes , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Lai Jiangshan , Zqiang , Ingo Molnar , Waiman Long , Mark Rutland , Thomas Gleixner , Vlastimil Babka , maged.michael@gmail.com, Mateusz Guzik , Jonas Oberhauser , rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@lists.linux.dev References: <20241004182734.1761555-1-mathieu.desnoyers@efficios.com> <20241004182734.1761555-4-mathieu.desnoyers@efficios.com> <20241005160444.GA18071@noisy.programming.kicks-ass.net> <20241005160723.GI33184@noisy.programming.kicks-ass.net> <6e7812f7-c94a-46ba-ba4d-cf4b7b1f60c9@efficios.com> <20241007104244.GC4879@noisy.programming.kicks-ass.net> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: <20241007104244.GC4879@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2024-10-07 12:42, Peter Zijlstra wrote: > On Sat, Oct 05, 2024 at 02:56:26PM -0400, Mathieu Desnoyers wrote: >> On 2024-10-05 18:07, Peter Zijlstra wrote: >>> On Sat, Oct 05, 2024 at 06:04:44PM +0200, Peter Zijlstra wrote: >>>> On Fri, Oct 04, 2024 at 02:27:33PM -0400, Mathieu Desnoyers wrote: >>> >>>>> +void hp_scan(struct hp_slot __percpu *percpu_slots, void *addr, >>>>> + void (*retire_cb)(int cpu, struct hp_slot *slot, void *addr)) >>>>> +{ >>>>> + int cpu; >>>>> + >>>>> + /* >>>>> + * Store A precedes hp_scan(): it unpublishes addr (sets it to >>>>> + * NULL or to a different value), and thus hides it from hazard >>>>> + * pointer readers. >>>>> + */ >>> >>> This should probably assert we're in a preemptible context. Otherwise >>> people will start using this in non-preemptible context and then we get >>> to unfuck things later. >> >> Something like this ? >> >> + /* Should only be called from preemptible context. */ >> + WARN_ON_ONCE(in_atomic()); > > lockdep_assert_preemption_enabled(); > > that also checks local IRQ state IIRC. I'll use this instead, thanks! Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com