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=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 14D88C433E0 for ; Fri, 15 Jan 2021 15:26:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8E01A2388B for ; Fri, 15 Jan 2021 15:26:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E01A2388B Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BE6368D018D; Fri, 15 Jan 2021 10:26:34 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B6E998D0187; Fri, 15 Jan 2021 10:26:34 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A36078D018D; Fri, 15 Jan 2021 10:26:34 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0155.hostedemail.com [216.40.44.155]) by kanga.kvack.org (Postfix) with ESMTP id 8A19C8D0187 for ; Fri, 15 Jan 2021 10:26:34 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 5631B1801B616 for ; Fri, 15 Jan 2021 15:26:34 +0000 (UTC) X-FDA: 77708386308.24.chess78_1a1827c27530 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id 39EA81A4AF for ; Fri, 15 Jan 2021 15:26:34 +0000 (UTC) X-HE-Tag: chess78_1a1827c27530 X-Filterd-Recvd-Size: 4743 Received: from mail-qv1-f46.google.com (mail-qv1-f46.google.com [209.85.219.46]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Fri, 15 Jan 2021 15:26:33 +0000 (UTC) Received: by mail-qv1-f46.google.com with SMTP id az16so4107893qvb.5 for ; Fri, 15 Jan 2021 07:26:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=aXa0cKHLVR9Tqw/zGTSb/zrOKdjPP+sDBHyXkAcY+V4=; b=Z5dIwm1tiQpDlio11nv3Wu0JOvwrkHcZBdkcpoDOgzMx8p6oxmUUnO5hDlzZFdwMaK F7qEBx6v4zKIEsI6Ygg38RQVXdyiTP6kBqhVxWlW5NCy5Hs7j1FlEyOh9LF/RiTFkYEB i4o3a32NPakRQ9+Vf/axEnED/LC619QBNBprODGEKzLuC8vdAzge2tB3lhNRVAgxSTiA LUOTRuW695jFnjeEw7dyu5YjVb2Jw4Wlf0HTBWkcV5Hm0RL1g2ZHS9LT6GTp3a32z/F4 wDfFGWe1IGcfg9n7znu3tPZho1WTHx/YD86hW8atWN7IKdMNknO/l9LV0iiAp1IXxGrY /tKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=aXa0cKHLVR9Tqw/zGTSb/zrOKdjPP+sDBHyXkAcY+V4=; b=JvsvwYJWbmL8Dzgaa7nwSvUe+u1griS2qA42eOJXKRfsRG5G0bOrCzhcmDgK08Z03S U+CWXQ5OxIv75qza8dsq11zbe/rjQNNPT/C1TShmwW54OiFT3jvwPwkCdJ408Od/AS7V kekr1JXHNMB0DmMLB4VoENRB5BgmnLvy/Evb+TMKKpfUt5VEp2D935FOEZSt9k07zozV e+9UbjR6/TYN7CRxVbw5PV2xNAoxMmqlZEN93Nzsv5xoJaHDJtP3Q0DwFfdRhbz5sqOF 6Hn+brXo5cKi4ugEXFtDNfpDA7oFDQYzzW+Ca8JtD59NbIWT0WAc2Pl44hQ161uijpRF 4ZJw== X-Gm-Message-State: AOAM5325dHiw+7ajX9LEvPL2STzQS2PKn7WGXRtn6cxHXpqEhTjdqMJk 1b/cuspdZ2/oD4sCFa4R59dWBe79qTzZUdL6z7r/0g== X-Google-Smtp-Source: ABdhPJyQr7uo9F3Xok26dWWKni/afho7+kX9trhxSvQzAZ6gyv9nrPMpYXAemIyqSyINcFaCdWe9igDRtPA5KH4ZL6g= X-Received: by 2002:ad4:47c4:: with SMTP id p4mr12699275qvw.23.1610724392534; Fri, 15 Jan 2021 07:26:32 -0800 (PST) MIME-Version: 1.0 References: <20210115130336.2520663-1-glider@google.com> <20210115130336.2520663-4-glider@google.com> In-Reply-To: From: Alexander Potapenko Date: Fri, 15 Jan 2021 16:26:21 +0100 Message-ID: Subject: Re: [PATCH v2 3/5] docs: ABI: add /sys/kernel/error_report/ documentation To: Greg KH Cc: LKML , Andrew Morton , Andrey Konovalov , Dmitriy Vyukov , Ingo Molnar , Marco Elver , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Linux Memory Management List Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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: > sysfs is "one value per file" What about existing interfaces that even export binary blobs through sysfs (e.g. /sys/firmware, /sys/boot_params)? What qualifies as a "value" in that case? > please put something like this in > tracefs, as there is no such rules there. Or debugfs, but please, not > sysfs. Does tracefs have anything similar to sysfs_notify() or any other way to implement a poll() handler? Our main goal is to let users wait on poll(), so that they don't have to check the file for new contents every now and then. Is it possible with tracefs or debugfs? Also, for our goal debugfs isn't a particularly good fit, as Android kernels do not enable debugfs. Not sure about tracefs, they seem to have it, need to check. Do you think it is viable to keep /sys/kernel/error_report/report_count in sysfs and use it for notifications, but move last_report somewhere else? (I'd probably prefer procfs, but it could be tracefs as well, if you find that better). This way it will still be possible to easily notify userspace about new reports, but the report itself won't have any atomicity guarantees. Users will have to check the report count to ensure it didn't change under their feet. > Also, any reason you didn't cc: the sysfs maintainers? Only my lack of common sense :) I'll add them should the following patches rely on sysfs, thank you! Alex -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg