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 7C28FC43333 for ; Sun, 22 Mar 2020 01:36:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5313920754 for ; Sun, 22 Mar 2020 01:36:29 +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 S1728176AbgCVBg2 (ORCPT ); Sat, 21 Mar 2020 21:36:28 -0400 Received: from mail-qk1-f193.google.com ([209.85.222.193]:42502 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726859AbgCVBg2 (ORCPT ); Sat, 21 Mar 2020 21:36:28 -0400 Received: by mail-qk1-f193.google.com with SMTP id e11so11524156qkg.9 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=SxYhNidDSFEycafF1zrgub26YvaXgc2FAmfC1KapGHhiwvDpUrRBbqouqEiVRW4fwc OJqyJ9RVs9DKbGPqH4+8ZzSkwkFl9t3UiLDBJl50Cj7lQxWf4ziFxTPN+7aS6jW9zmuX EcEJcd1pd7TlU03bi+V3UKqA3yUWZoRFBvlMw+At7hNatkEkrJFZsGKWzEv/h9Rb7YXQ 94VtIWwK4tzlb9JL9xx9aqVPfuUL+wny945KAGxmA9mD6GVG1zGzdetd6qaNISTuey4P nLD3uyhCY0dS0lEvqPRrNA+dicdhQXxCzv7VrOYlxMwR9X2EftWnnih7AaU7Y2zrxWp7 dMHg== X-Gm-Message-State: ANhLgQ3bE6IIt3z7NDjtehxT6Sof6Aptrg9WPTK8UXH8Z0e0h5ikdjLF yND4AYZsdQMCUypJrJjjm6oxjg== 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-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@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