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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB4ABC433EF for ; Sat, 26 Mar 2022 22:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235303AbiCZWnr (ORCPT ); Sat, 26 Mar 2022 18:43:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235178AbiCZWnk (ORCPT ); Sat, 26 Mar 2022 18:43:40 -0400 Received: from mail-lf1-x12c.google.com (mail-lf1-x12c.google.com [IPv6:2a00:1450:4864:20::12c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67EE5340DE for ; Sat, 26 Mar 2022 15:42:03 -0700 (PDT) Received: by mail-lf1-x12c.google.com with SMTP id m3so18965352lfj.11 for ; Sat, 26 Mar 2022 15:42:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=lSLy1cPxoDC//3e7623ZX4es74MP3w4cCLgF29j5fUU=; b=HTqOpqutn/t7/GJQrakk/gAhabnVwnukxwMtMja/1SljWHCaJh+ZhMav3V4OqLq1/m JldSGIs54yIcMbIeQmTLdzLUuMQeARuWCJqZUzEEphC4IEXZ9NChSkH88YY0FSWwPQJu U24K7ZOq8FQZ2yFFgeY8MWj+ZVkdrqhAUb3Tw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=lSLy1cPxoDC//3e7623ZX4es74MP3w4cCLgF29j5fUU=; b=KUabKEU7EF93Ng2nE14XanAUhpOZRA1OJ/VKNOd4B0p0F+Y+9hoBfi4RLPSskO+Nta QGBzYAXl9+XcUs8xzVz3xBRzt9BJC9vqis7VMXMHu4isoDmypBq+OD6v2dYUP51w9d2i MumIvFdW0efKSllRTW83OqP1kP3ECx0N3IkkPZOzlABWlgj9xzJG7DGajRpoNz6wZvyG ywAlYnI7H+8c7+LMy25q0lpqLyEvWgMe6AbFBaMn64zdb+QMSquXQUrW0eSoWvnXl0/3 s4n9lv8UdPdfZoNCmiDDUqVKiA+fSx6Lcaha7hUwnrmbyubkjoa8EAVaBujLJa/dETR5 w+Rw== X-Gm-Message-State: AOAM531Y+o2OqjPZS8NnHXpj39P5vUcZ2L8lOqZRIimnTl2CE8oB45Uw wUxZHu2GT2pamUOqouTt4gkuFUjCcK8TQfkLrd0= X-Google-Smtp-Source: ABdhPJzkSDAZevLjB6dzK2H6ZDLoKdl95Z7MPS1Ui+sgkJZswymPcuvOpbxDwC5SHvrV0tnRi0bkkw== X-Received: by 2002:ac2:41c4:0:b0:445:9a7c:b76f with SMTP id d4-20020ac241c4000000b004459a7cb76fmr13064151lfi.497.1648334521438; Sat, 26 Mar 2022 15:42:01 -0700 (PDT) Received: from mail-lf1-f48.google.com (mail-lf1-f48.google.com. [209.85.167.48]) by smtp.gmail.com with ESMTPSA id x16-20020a0565123f9000b0044839be14ddsm1188044lfa.76.2022.03.26.15.41.57 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 26 Mar 2022 15:41:59 -0700 (PDT) Received: by mail-lf1-f48.google.com with SMTP id p10so13130213lfa.12 for ; Sat, 26 Mar 2022 15:41:57 -0700 (PDT) X-Received: by 2002:a05:6512:b13:b0:448:90c6:dc49 with SMTP id w19-20020a0565120b1300b0044890c6dc49mr13805287lfu.542.1648334517200; Sat, 26 Mar 2022 15:41:57 -0700 (PDT) MIME-Version: 1.0 References: <1812355.tdWV9SEqCh@natalenko.name> <20220324055732.GB12078@lst.de> <4386660.LvFx2qVVIh@natalenko.name> <81ffc753-72aa-6327-b87b-3f11915f2549@arm.com> <878rsza0ih.fsf@toke.dk> <4be26f5d8725cdb016c6fdd9d05cfeb69cdd9e09.camel@freebox.fr> <20220324163132.GB26098@lst.de> <871qyr9t4e.fsf@toke.dk> <31434708dcad126a8334c99ee056dcce93e507f1.camel@freebox.fr> <20220326003853.44c3285c.pasic@linux.ibm.com> <8735j47l7y.fsf@toke.dk> In-Reply-To: From: Linus Torvalds Date: Sat, 26 Mar 2022 15:41:40 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [REGRESSION] Recent swiotlb DMA_FROM_DEVICE fixes break ath9k-based AP To: David Laight Cc: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= , Halil Pasic , Robin Murphy , Maxime Bizon , Netdev , Kalle Valo , linux-wireless , Oleksandr Natalenko , stable , "David S. Miller" , iommu , Olha Cherevyk , Greg Kroah-Hartman , Jakub Kicinski , Paolo Abeni , Christoph Hellwig , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 26, 2022 at 3:38 PM David Laight wrote: > > Is the idea of 'buffer ownership' even a good one? I do think it might be best to not think in those terms, but literally just in data movement terms. Because the "buffer ownership" mental model is clearly confused, when data transfer might be ongoing, but the CPU might need to just look at "what's going on right now" without actually taking any ownership of the buffer. Linus