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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E9C3C4332D for ; Sun, 22 Mar 2020 01:36:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E3C920767 for ; Sun, 22 Mar 2020 01:36:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="PL1RyTyq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728316AbgCVBg2 (ORCPT ); Sat, 21 Mar 2020 21:36:28 -0400 Received: from mail-qk1-f196.google.com ([209.85.222.196]:39905 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728288AbgCVBg2 (ORCPT ); Sat, 21 Mar 2020 21:36:28 -0400 Received: by mail-qk1-f196.google.com with SMTP id b62so2202425qkf.6 for ; Sat, 21 Mar 2020 18:36:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Ubq/qZnX/ujKaYfjOueGLD6Nqh5QSMEUH2vduTkKjHA=; b=PL1RyTyq/WRZKZrEHqL4R/7W0dJU38ey6RtLKNXSwKxSkIN9TA8rk+1XHkXSB34Z3U +hT8qUXMqZjtKTftKJLwunclFMXbCFua88wGTvXHtsD23zMsiUUWyiPeyIJ6vgtbThHW gFwhM+xyJWfZ3VhmNgEQUPD4gXknbn5mHpUV8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Ubq/qZnX/ujKaYfjOueGLD6Nqh5QSMEUH2vduTkKjHA=; b=nKwEeCoor+rtGDo3R3dg4N33IkAmpZnrYQCYVBkAd+xsfQone5bgdO3bcKz1hOMHEp WLshT9r6/0q6Khucqp4GNzqUEzV23xgoRyoTmhti9lssTgQ106ZhH+1PaEQZe5rb/rMY j1zsRkdVFay9hIxc1Np5tYVCZWH/8VFT51j9fi1Ven8cEcpanM8HTpxAoWhqC30a903z MNPt+LWF4X7lYilvQ7uSQhvbSwmHPOpQvqaemrKDRi0IkRy/q9u9XSwO1Oez3gWpTOnY Rle0PR3K0ynU9NNsgyxw1CvOoiwXLnLBewKlQXss/jZpy8mZALXUN+GyXjOeLH3rt9uQ NHoA== X-Gm-Message-State: ANhLgQ2iWQfm22PuGhHW47aJ/12XygdWthcWMCNRHF3dbTInAhLWD4Bb PoIn9D7mAgG6hbM0dfAXHmTkaA== X-Google-Smtp-Source: ADFU+vu+Jf1CVw4GQOx5dNoxGTymqpn5p1dmtyWCTiwwU99STlnO5FKSrpzUOQTz2PYCKmBpD/vEgA== X-Received: by 2002:a37:db0a:: with SMTP id e10mr2637693qki.273.1584840985412; Sat, 21 Mar 2020 18:36:25 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id w18sm7979664qkw.130.2020.03.21.18.36.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Mar 2020 18:36:24 -0700 (PDT) Date: Sat, 21 Mar 2020 21:36:24 -0400 From: Joel Fernandes To: Thomas Gleixner Cc: LKML , Peter Zijlstra , Linus Torvalds , Ingo Molnar , Will Deacon , "Paul E . McKenney" , Steven Rostedt , Randy Dunlap , Sebastian Andrzej Siewior , Logan Gunthorpe , Kurt Schwemmer , Bjorn Helgaas , linux-pci@vger.kernel.org, Felipe Balbi , Greg Kroah-Hartman , linux-usb@vger.kernel.org, Kalle Valo , "David S. Miller" , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, Oleg Nesterov , Davidlohr Bueso , Michael Ellerman , Arnd Bergmann , linuxppc-dev@lists.ozlabs.org Subject: Re: [patch V2 08/15] Documentation: Add lock ordering and nesting documentation Message-ID: <20200322013624.GA161885@google.com> References: <20200318204302.693307984@linutronix.de> <20200318204408.211530902@linutronix.de> <20200321212144.GA6475@google.com> <874kuhqsz3.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874kuhqsz3.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Sat, Mar 21, 2020 at 10:49:04PM +0100, Thomas Gleixner wrote: [...] > >> +rwsems have grown interfaces which allow non owner release for special > >> +purposes. This usage is problematic on PREEMPT_RT because PREEMPT_RT > >> +substitutes all locking primitives except semaphores with RT-mutex based > >> +implementations to provide priority inheritance for all lock types except > >> +the truly spinning ones. Priority inheritance on ownerless locks is > >> +obviously impossible. > >> + > >> +For now the rwsem non-owner release excludes code which utilizes it from > >> +being used on PREEMPT_RT enabled kernels. > > > > I could not parse the last sentence here, but I think you meant "For now, > > PREEMPT_RT enabled kernels disable code that perform a non-owner release of > > an rwsem". Correct me if I'm wrong. > > Right, that's what I wanted to say :) > > Care to send a delta patch? Absolutely, doing that now. :-) thanks, - Joel 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 X-Spam-Level: X-Spam-Status: No, score=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCBEFC4332D for ; Sun, 22 Mar 2020 01:38:06 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3E41A20754 for ; Sun, 22 Mar 2020 01:38:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="PL1RyTyq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3E41A20754 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48lKs74WBlzDrh8 for ; Sun, 22 Mar 2020 12:38:03 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=joelfernandes.org (client-ip=2607:f8b0:4864:20::743; helo=mail-qk1-x743.google.com; envelope-from=joel@joelfernandes.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=joelfernandes.org header.i=@joelfernandes.org header.a=rsa-sha256 header.s=google header.b=PL1RyTyq; dkim-atps=neutral Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48lKqM169KzDrgK for ; Sun, 22 Mar 2020 12:36:29 +1100 (AEDT) Received: by mail-qk1-x743.google.com with SMTP id i6so2483412qke.1 for ; Sat, 21 Mar 2020 18:36:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Ubq/qZnX/ujKaYfjOueGLD6Nqh5QSMEUH2vduTkKjHA=; b=PL1RyTyq/WRZKZrEHqL4R/7W0dJU38ey6RtLKNXSwKxSkIN9TA8rk+1XHkXSB34Z3U +hT8qUXMqZjtKTftKJLwunclFMXbCFua88wGTvXHtsD23zMsiUUWyiPeyIJ6vgtbThHW gFwhM+xyJWfZ3VhmNgEQUPD4gXknbn5mHpUV8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Ubq/qZnX/ujKaYfjOueGLD6Nqh5QSMEUH2vduTkKjHA=; b=edHOSvlRSH0v4bN/+FwfsALVCIt15oy8dYqNfdjs8e8iayUGh0ibibRjFZVqBe6727 R41SH+zIRsQo13nWP0u2IXde6633c+8HWytjzlY9bGKrKv/Ml/642p+MFfYFGuba+PUD 4NL5WKnWmC937bVMeLL6ndCergBF4iFKzLyeX8TUx05zpCz5IBsMULq7Am7nFo/cUVkc vg0wSR5G63+OMylCWKydkAlFj4otu7pNV6aHBgWF96LAmgPrzNRzAgyUeVYMy2yFhDlJ 8vFETLfgzzHDJBRhqSBmMbvqvHElIHwxKzaJ0mkqQtHDOlgzPrlLKXatx9uzW+Fxc8yj Y5sA== X-Gm-Message-State: ANhLgQ1XHbFRfo/qsq73jlBDL+jB3xBchFm24rk7dYKCKmsscEM7IE8U 13s7fAIThIFTh57+IffoTSgRFg== X-Google-Smtp-Source: ADFU+vu+Jf1CVw4GQOx5dNoxGTymqpn5p1dmtyWCTiwwU99STlnO5FKSrpzUOQTz2PYCKmBpD/vEgA== X-Received: by 2002:a37:db0a:: with SMTP id e10mr2637693qki.273.1584840985412; Sat, 21 Mar 2020 18:36:25 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id w18sm7979664qkw.130.2020.03.21.18.36.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 21 Mar 2020 18:36:24 -0700 (PDT) Date: Sat, 21 Mar 2020 21:36:24 -0400 From: Joel Fernandes To: Thomas Gleixner Subject: Re: [patch V2 08/15] Documentation: Add lock ordering and nesting documentation Message-ID: <20200322013624.GA161885@google.com> References: <20200318204302.693307984@linutronix.de> <20200318204408.211530902@linutronix.de> <20200321212144.GA6475@google.com> <874kuhqsz3.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874kuhqsz3.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.12.2 (2019-09-21) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Randy Dunlap , Peter Zijlstra , linux-pci@vger.kernel.org, Sebastian Andrzej Siewior , Oleg Nesterov , Will Deacon , Ingo Molnar , Davidlohr Bueso , Arnd Bergmann , Logan Gunthorpe , "Paul E . McKenney" , linuxppc-dev@lists.ozlabs.org, Steven Rostedt , Bjorn Helgaas , Kurt Schwemmer , Kalle Valo , Felipe Balbi , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, LKML , netdev@vger.kernel.org, Linus Torvalds , "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sat, Mar 21, 2020 at 10:49:04PM +0100, Thomas Gleixner wrote: [...] > >> +rwsems have grown interfaces which allow non owner release for special > >> +purposes. This usage is problematic on PREEMPT_RT because PREEMPT_RT > >> +substitutes all locking primitives except semaphores with RT-mutex based > >> +implementations to provide priority inheritance for all lock types except > >> +the truly spinning ones. Priority inheritance on ownerless locks is > >> +obviously impossible. > >> + > >> +For now the rwsem non-owner release excludes code which utilizes it from > >> +being used on PREEMPT_RT enabled kernels. > > > > I could not parse the last sentence here, but I think you meant "For now, > > PREEMPT_RT enabled kernels disable code that perform a non-owner release of > > an rwsem". Correct me if I'm wrong. > > Right, that's what I wanted to say :) > > Care to send a delta patch? Absolutely, doing that now. :-) thanks, - Joel