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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 17633C433FF for ; Mon, 5 Aug 2019 08:32:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB1112067D for ; Mon, 5 Aug 2019 08:32:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564993972; bh=X3DsxvoUyO8BWT9Rmk+NqY4rLPfy+td+0CCjsLeLrsw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=YMYPMg90enAW7//fPCuSb7oSRfz2vvvTQeL61otklgapv+/CISuqLoGwKi7cx0ccG pxcPq1VmahxcIItq2YheQhsb1jyfFqiMV+XFzRhNQFYQ2pO2QSrHvBEbpQSy+Tu2x6 yjrUoEjAtm+lMdmC5EPBPYY1yQoxa+IYphth7Xf4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727862AbfHEIcu (ORCPT ); Mon, 5 Aug 2019 04:32:50 -0400 Received: from mail-ot1-f66.google.com ([209.85.210.66]:46176 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726423AbfHEIcu (ORCPT ); Mon, 5 Aug 2019 04:32:50 -0400 Received: by mail-ot1-f66.google.com with SMTP id z23so56111018ote.13; Mon, 05 Aug 2019 01:32:50 -0700 (PDT) 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; bh=zN5arBluSaU7iuMkb1bdkzd/J9ztzBg1fZtHM8/6PEw=; b=rOsWPRG/CSdeweQgt2Id0UaxTCZNcJT4KnwCxTHY5qNyWZRY4ANwyxqlpeYxvKBDeo 5cMJp+uQVqrSZII/tpaOnjhf13UP3r+96Cp4P7LnWShaVWnwqHtzzKwplGCuppilobca 1lPfT1/SaRa7fN1R+sFsWhaph3fa2MiA4QNppsgsc/YSfUdddcidUMPPGrY/GEc4mGba INkSwS2sJauZDMFM3AbsQ9ckOak6HdG+1s5qx3fy5/SCLmSa8wbaw36zDUQOP1rcFZAp LYzale9DriEbFELhDMYcfPJjyNB5ZjOIBoj17cbYha9JjaxVlZ07Gdh2k4HKQZxb/YH8 VvJA== X-Gm-Message-State: APjAAAXI9jju8BawSMnNZ4wRtS2TSnZ24SR9obcnA0a5BWOaTDf+X46A 1XgcsfQ9DllmxrLzR2U863wjD7eFD6l562qOcio= X-Google-Smtp-Source: APXvYqxi/zGwKaFeEyCdwqytMLCi1mCgwjaO4WgXUM53T9921kaMZ1kccxf7zKH1cxGKvNJhRPvfgPSROUeermemRI8= X-Received: by 2002:a05:6830:1516:: with SMTP id k22mr106178174otp.189.1564993969706; Mon, 05 Aug 2019 01:32:49 -0700 (PDT) MIME-Version: 1.0 References: <20190731215514.212215-1-trong@android.com> <32598586.Mjd66ZhNnG@kreacher> <6987393.M0uybTKmdI@kreacher> <5d42281c.1c69fb81.bcda1.71f5@mx.google.com> <5d434a23.1c69fb81.c4201.c65b@mx.google.com> In-Reply-To: From: "Rafael J. Wysocki" Date: Mon, 5 Aug 2019 10:32:35 +0200 Message-ID: Subject: Re: [PATCH v6] PM / wakeup: show wakeup sources stats in sysfs To: Tri Vo Cc: "Rafael J. Wysocki" , Stephen Boyd , "Rafael J. Wysocki" , Greg Kroah-Hartman , Viresh Kumar , Hridya Valsaraju , Sandeep Patil , Kalesh Singh , Ravi Chandra Sadineni , LKML , Linux PM , "Cc: Android Kernel" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 4, 2019 at 12:40 AM Tri Vo wrote: > > On Thu, Aug 1, 2019 at 3:10 PM Rafael J. Wysocki wrote: > > > > On Thu, Aug 1, 2019 at 11:45 PM Tri Vo wrote: > > > > > > On Thu, Aug 1, 2019 at 1:23 PM Stephen Boyd wrote: > > > > > > > > Quoting Tri Vo (2019-08-01 12:50:25) > > > > > On Wed, Jul 31, 2019 at 4:45 PM Stephen Boyd wrote: > > > > > > > > > > > > Quoting Rafael J. Wysocki (2019-07-31 16:10:38) > > > > > > > On Thu, Aug 1, 2019 at 12:59 AM Tri Vo wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > So why wouldn't something like this suffice: > > > > > > > > > > > > > > > > > > dev = device_create_with_groups(wakeup_class, parent, MKDEV(0, 0), ws, > > > > > > > > > wakeup_source_groups, "wakeup:%s", ws->name); > > > > > > > > > > > > > > > > > > ? > > > > > > > > > > > > > > > > ws->name is inherited from the device name. IIUC device names are not > > > > > > > > guaranteed to be unique. So if different devices with the same name > > > > > > > > register wakeup sources, there is an error. > > > > > > > > > > > > > > OK > > > > > > > > > > > > > > So I guess the names are retained for backwards compatibility with > > > > > > > existing user space that may be using them? > > > > > > > > > > > > > > That's kind of fair enough, but having two different identification > > > > > > > schemes for wakeup sources will end up confusing. > > > > > > > > > > > > I understand your concern about the IDA now. Thanks for clarifying. > > > > > > > > > > > > How about we name the devices 'wakeupN' with the IDA when they're > > > > > > registered with a non-NULL device pointer and then name them whatever > > > > > > the name argument is when the device pointer is NULL. If we have this, > > > > > > we should be able to drop the name attribute in sysfs and figure out the > > > > > > name either by looking at the device name in /sys/class/wakeup/ if it > > > > > > isn't 'wakeupN', or follow the symlink to the device in /sys/devices/ > > > > > > and look at the parent device name there. > > > > > > > > > > This makes it difficult for userspace to query the name a wakeup > > > > > source, as it now has to first figure out if a wakeup source is > > > > > associated with a device or not. The criteria for that is also > > > > > awkward, userspase has to check if directory path contains "wakeupN", > > > > > then it's a virtual wakeup source. > > > > > > > > I think you mean if it doesn't match wakeupN then it's a virtual wakeup > > > > source? > > > > > > Yes > > > > > > > > > > > > > > IMO it's cleaner to consistently have /sys/class/wakeup/wakeupN/name > > > > > for every wakeup source. > > > > > > > > I don't find it awkward or difficult. Just know what the name of the > > > > /sys/class/wakeup/ path is and then extract the name from there if it > > > > doesn't match wakeupN, otherwise read the 'device' symlink and run it > > > > through basename. > > > > > > The concern was that having both "id" and "name" around might be > > > confusing. I don't think that making the presence of "name" > > > conditional helps here. And we have to maintain additional logic in > > > both kernel and userspace to support this. > > > > > > Also, say, userspace grabs a wakelock named "wakeup0". In the current > > > patch, this results in a name collision and an error. Even assuming > > > that userspace doesn't have ill intent, it still needs to be aware of > > > "wakeupN" naming pattern to avoid this error condition. > > > > > > All wakeup sources in the /sys/class/wakeup/ are in the same namespace > > > regardless of where they originate from, i.e. we have to either (1) > > > inspect the name of a wakeup source and make sure it's unique before > > > using it as a directory name OR (2) generate the directory name on > > > behalf of whomever is registering a wakeup source, which I think is a > > > much simpler solution. > > > > OK, whatever. > > > > Let's use the IDA as originally proposed and retain the names for > > backwards compatibility only. > > > > Maybe just allocate the ID at the wakeup source object creation time > > already (ISTR that you did that before attempting to create a virtual > > device for the wakeup source). > > Yes, allocating the ID when creating the wakeup source object makes > sense. However, kernel/power/wakelock.c allocates its wakeup sources > manually. I imagine we don't want these IDs to be created in more than > one place. No, we don't. > Making wakelock.c only use wakeup_source_*() family of functions when > dealing with wakeup sources might be a worthwhile change though. Then > we won't have to worry about ID allocation in wakelock.c. WDYT? Sounds reasonable to me. > Also, it sounds like we all agree with "/sys/class/wakeup/wsN/" path > and "/sys/class/wakeup/wsN/name" attribute for each wakeup source, > right? Generally yes, but please make it "wakeupN".