From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anton Vorontsov Subject: Re: [PATCH v2 2/3] bq2415x_charger: Use power_supply notifier for automode Date: Sun, 1 Dec 2013 16:24:44 -0800 Message-ID: <20131202002444.GA22418@teo> References: <1378630239-10006-1-git-send-email-pali.rohar@gmail.com> <1384856285-19593-3-git-send-email-pali.rohar@gmail.com> <201311242001.23126@pali> <20131201223730.GD6271@lizard> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from mail-pb0-f47.google.com ([209.85.160.47]:49091 "EHLO mail-pb0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752426Ab3LBAYs (ORCPT ); Sun, 1 Dec 2013 19:24:48 -0500 Received: by mail-pb0-f47.google.com with SMTP id um1so17719160pbc.34 for ; Sun, 01 Dec 2013 16:24:47 -0800 (PST) Content-Disposition: inline In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Michael Trimarchi Cc: Pali =?utf-8?B?Um9ow6Fy?= , David Woodhouse , Tony Lindgren , Russell King , linux-kernel@vger.kernel.org, Linux OMAP Mailing List , freemangordon@abv.bg, aaro.koskinen@iki.fi, pavel@ucw.cz On Mon, Dec 02, 2013 at 01:02:40AM +0100, Michael Trimarchi wrote: > On Sun, Dec 1, 2013 at 11:37 PM, Anton Vorontsov wrote: > > On Mon, Nov 25, 2013 at 08:16:34PM +0100, Michael Trimarchi wrote: > > ... > >> >> So you can read this value without any type of synchronization > >> >> with the power_supply_core > >> >> and sysfs implementation? > > ... > >> https://lists.ubuntu.com/archives/kernel-team/2013-January/025206.html > >> > >> I found and equivalent scenario that I was trying to said > > > > That's a good question, actually. Even though in Pali's case the notifier > > is atomic (so that we are pretty confident that the object won't be > > unregistered), there is still a possiblity of a dead lock, for example. So > > So if the get_property is a sleeping function it will be a deadlock. Right? All kind of bad things might happen, yes. But before that I would expect a bunch of warnings from might_sleep() stuff. I would recommend to test the patches using preempt/smp kernels + various DEBUG_ kernel options set. Thanks, Anton