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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 537CBC31E40 for ; Sat, 3 Aug 2019 22:40:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24EC121655 for ; Sat, 3 Aug 2019 22:40:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="D83qNIa5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729178AbfHCWkR (ORCPT ); Sat, 3 Aug 2019 18:40:17 -0400 Received: from mail-ot1-f65.google.com ([209.85.210.65]:40305 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729193AbfHCWkP (ORCPT ); Sat, 3 Aug 2019 18:40:15 -0400 Received: by mail-ot1-f65.google.com with SMTP id l15so24517603oth.7 for ; Sat, 03 Aug 2019 15:40:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/PnAF0cDT4FW6fygrxyjeBHNYfYv5JYH6/0TJwjf57E=; b=D83qNIa5PBWamlgp8wmv5d8Jv8sW3sgp43cF1YCh37xOULzF89TW9a1bIHRSH+++qI lXvZQrR2wOBvwSD5SLKxyj9mVt+UJale2LqAaat9EEFqAjUgwtgAdtFsFGmdHaedEDVn /PMtg14FoB6f2lpMwkSmib31/vaL3M9mAq9C2b55sMRpoZvBXqWDx/+5UkvdF4V8MjK8 C9OPO3Fk4hSZL3Ld8JVSBIV92zWzowlk9PNIHGAhJILZBS/fMJB2M1gqC8fftattIwbE PSv+GJdhUgBmLk1lZYsXn7CwqVnJSOsMbDLbR+H1vAXO55oX5v49NDqY/3RTgoIN7A1a qG4g== 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=/PnAF0cDT4FW6fygrxyjeBHNYfYv5JYH6/0TJwjf57E=; b=mdUuuglo+CMoMFLLshT51BmGiOzcUlMetoPI8LfnkhCcoVxcmprRwtuoF5ybmGL8Z9 QnazLMWpkhujlZZAdwaHpKK6uDRMc9fL15BMYc4KWejXWYdWl+bbdan0CSDkF8lxEUR4 mJvIUYS8BCK8/Wwb0WzYsc97vfsrDAp7JZ7s5+iQbd67X/qgkHX87nGow7ep42t6ovi8 fWgItm2NvusGaueI5bJ7HevkoIXYickeRlVhRI8YJi51j95Q5fLr9WgCnU93h8JDcci5 vwU4NRM6cZl0tV34Keth/XztM8CVcP62N2IwmtcRXGKooNQjssdRl509eYirHZ2B3D3Y Z4+Q== X-Gm-Message-State: APjAAAW1ciTM3ZijPn6cp0rp7vuQ/Q1A6dB6VPUnKD6z2cfgsQ8fQDjq PL5sprcwtBXookQ3isBhrd5z0H+6B/Sm5fpuUUc= X-Google-Smtp-Source: APXvYqxb2Y5awtaM3qAadatWBkFPpS8SJ8iIicCMByvpBw8ugltNVEw40uTziaiRSS/D+QO+KMWz+BLIhidCE5z4s9M= X-Received: by 2002:a9d:5f02:: with SMTP id f2mr21903585oti.148.1564872014330; Sat, 03 Aug 2019 15:40:14 -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: Tri Vo Date: Sat, 3 Aug 2019 15:40:03 -0700 Message-ID: Subject: Re: [PATCH v6] PM / wakeup: show wakeup sources stats in sysfs To: "Rafael J. Wysocki" Cc: 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-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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. 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? 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?