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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 55265D3E792 for ; Thu, 11 Dec 2025 11:49:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9A3846B0005; Thu, 11 Dec 2025 06:49:19 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 954B66B0007; Thu, 11 Dec 2025 06:49:19 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86A776B0008; Thu, 11 Dec 2025 06:49:19 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 76B5D6B0005 for ; Thu, 11 Dec 2025 06:49:19 -0500 (EST) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 0BE19BB9B0 for ; Thu, 11 Dec 2025 11:49:19 +0000 (UTC) X-FDA: 84207019638.01.0C45795 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf18.hostedemail.com (Postfix) with ESMTP id 432C41C0008 for ; Thu, 11 Dec 2025 11:49:17 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=JVN1AzMs; spf=none (imf18.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org; dmarc=pass (policy=none) header.from=infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1765453757; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+OT4ivkTtGpyfGWvpgrf0Vr9j9IriXFLaXkwu0GJ6bw=; b=ZvXnEusH8yctKgG6zECokrDsd0OglZbR5DE19gGckjo6BG3jAJKY3qduKKgt1LOOtII70C SaRmAAAg7HjnPXi+pqP2ZzG9ys6dtA4uWXUaNU/Xpf0GW0RdtMs+8W7n0RhPgBR1rhPLoX ShYpOAGXq1Ow0rDVmNDeLpR8h+TuYqw= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=JVN1AzMs; spf=none (imf18.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org; dmarc=pass (policy=none) header.from=infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765453757; a=rsa-sha256; cv=none; b=VmJVhq4cDxdYR/Mh6sa7tZ11KxpDyYvMRCanXh4aznCmwH1WLWoueWWmpuYlzXIXjYPm/7 GOGW3kDrZvUt+ucltdkGKXdZHJLRsn2l3ADL8FN/AJH6KyTiqgRiNfVxKlCNjUm7kpnnQK zCCWS79xlZxJSRQU6StwfY63lLOzgKA= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=+OT4ivkTtGpyfGWvpgrf0Vr9j9IriXFLaXkwu0GJ6bw=; b=JVN1AzMsYXKkNnwNeBL1OpOC2M usRg9+5aFTrJDHOxEclPH1av467Fb3Bj3rPgMyCbJ5gZYycl9Gw6AjdhzpiLl3C0V9sb1i0yaQfRK mOf5ZYG2z9itaINLA0tfLNeKZSZyiW/C+oVjaNH6gOgA3m+gKuZvovx8NVkI5qpnHg6IQDV9R9c1T fyzEc9WqyUb15CtUOl/P9FkFgRDq1JVhxqr2lfHMG4MfmM6gG4CgJ90xouVD4A2O/wBERNIxj9gwr pYbXQ1fHOXH+zv5KIkiK43jA/QtjxQp5F0m7a8f08ERF19UcmgOhPesOMjYZXmUqtsp+gyMa2Aosq y9tldtSA==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTfAP-0000000EBca-31xd; Thu, 11 Dec 2025 11:49:05 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 2CEC930301A; Thu, 11 Dec 2025 12:49:05 +0100 (CET) Date: Thu, 11 Dec 2025 12:49:05 +0100 From: Peter Zijlstra To: Marco Elver Cc: Boqun Feng , Ingo Molnar , Will Deacon , "David S. Miller" , Luc Van Oostenryck , Chris Li , "Paul E. McKenney" , Alexander Potapenko , Arnd Bergmann , Bart Van Assche , Christoph Hellwig , Dmitry Vyukov , Eric Dumazet , Frederic Weisbecker , Greg Kroah-Hartman , Herbert Xu , Ian Rogers , Jann Horn , Joel Fernandes , Johannes Berg , Jonathan Corbet , Josh Triplett , Justin Stitt , Kees Cook , Kentaro Takeda , Lukas Bulwahn , Mark Rutland , Mathieu Desnoyers , Miguel Ojeda , Nathan Chancellor , Neeraj Upadhyay , Nick Desaulniers , Steven Rostedt , Tetsuo Handa , Thomas Gleixner , Thomas Graf , Uladzislau Rezki , Waiman Long , kasan-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-sparse@vger.kernel.org, linux-wireless@vger.kernel.org, llvm@lists.linux.dev, rcu@vger.kernel.org Subject: Re: [PATCH v4 08/35] locking/rwlock, spinlock: Support Clang's context analysis Message-ID: <20251211114905.GE3911114@noisy.programming.kicks-ass.net> References: <20251120145835.3833031-2-elver@google.com> <20251120151033.3840508-7-elver@google.com> <20251120151033.3840508-9-elver@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251120151033.3840508-9-elver@google.com> X-Stat-Signature: bems68mqfy75hwfapew3dghjjbnfrbq3 X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 432C41C0008 X-HE-Tag: 1765453757-673782 X-HE-Meta: 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 slgkvc59 Cg+6ZLHa0jf6Atp6becqNFQQ7KxeDqwA6XO3uVxcICrDcm0SUPUJrnOWXuvoLQOuoq4H556TcHgkjOcDZPrW81uslAEYJL50QRurlz+uvXzBZgFcYj+/GvDt8s+aijU2V3RV9Z3QwRYcZXO8rsM58YCmMwxT1ScU1fKcTgZ4L6aVQZ2gWr6uxZHLyUsVZFKPipGMbrHPm+02tsXz6vWom5Cj/XSgYUvQseJOqTkAUkXlDFB3TmjJhCCm5quY/I2HS/KmLJmUV+IDvU20AaxZHY2xHKA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Nov 20, 2025 at 04:09:33PM +0100, Marco Elver wrote: > To avoid warnings in constructors, the initialization functions mark a > lock as acquired when initialized before guarded variables. > diff --git a/include/linux/rwlock.h b/include/linux/rwlock.h > index 5b87c6f4a243..a2f85a0356c4 100644 > --- a/include/linux/rwlock.h > +++ b/include/linux/rwlock.h > @@ -22,23 +22,24 @@ do { \ > static struct lock_class_key __key; \ > \ > __rwlock_init((lock), #lock, &__key); \ > + __assume_ctx_guard(lock); \ > } while (0) > #else > # define rwlock_init(lock) \ > - do { *(lock) = __RW_LOCK_UNLOCKED(lock); } while (0) > + do { *(lock) = __RW_LOCK_UNLOCKED(lock); __assume_ctx_guard(lock); } while (0) > #endif This is again somewhat magical and confused the living daylight out of me. I know (from having looked back on previous discussions) that I was confused about this before, and clearly it didn't stick. So obviously I'll be confused again when I look at this code in a years time or so :/ Can we get a comment near this __assume_ctx_guard() thing (because putting it all over the lock initializers would probably be duplicating things too much)?