From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756967Ab1JNVrs (ORCPT ); Fri, 14 Oct 2011 17:47:48 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59094 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751012Ab1JNVrr (ORCPT ); Fri, 14 Oct 2011 17:47:47 -0400 Date: Sat, 15 Oct 2011 08:47:32 +1100 From: NeilBrown To: Alan Stern Cc: markgross@thegnar.org, , John Stultz , "Rafael J. Wysocki" , , , , "Dmitry Fink (Palm GBU)" , , , Magnus Damm , , Subject: Re: [markgross@thengar.org: [RFC] wake up notifications and suspend blocking (aka more wakelock stuff)] Message-ID: <20111015084732.5fe55467@notabene.brown> In-Reply-To: References: <20111013163526.3863be01@notabene.brown> X-Mailer: Claws Mail 3.7.10 (GTK+ 2.22.1; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/IEIBn21qZz3y6Slr_r+syJq"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/IEIBn21qZz3y6Slr_r+syJq Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 13 Oct 2011 11:16:23 -0400 (EDT) Alan Stern wrote: > On Thu, 13 Oct 2011, NeilBrown wrote: >=20 > > Nope, but I'm keen for you to convince me. Identify a wakeup event that > > cannot be made visible to poll (or to user-space by some other > > mechanism) before the wakeup_source needs to be deactivated. Or if I've > > misunderstood what sort of notification is problematic, help me underst= and. >=20 > Here's an example (just for kicks, not completely relevant to your > discussion): A USB keyboard key release. Unlike key presses, key > releases need not generate input events. If no processes are > monitoring the raw keyboard event queue then the release is not visible > to userspace at all, hence not visible before the wakeup_source needs > to be deactivated. >=20 > Alan Stern As you say, not completely relevant. If a tree falls in a forest with no one to here, does it make a sound? similarly if an event happens that no-one is looking for, is it visible? It doesn't really matter. So at most this is a case of "is not made visible" rather than "cannot be made visible". The key-release just needs to clear the "key is pressed" state so that auto-repeat stops and if it was a modifier, the modification is discarded. That is all trivially done in some kernel driver while the wakeup_source is active. Thanks, NeilBrown --Sig_/IEIBn21qZz3y6Slr_r+syJq Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBTpit9Dnsnt1WYoG5AQKAzg//fU59Ufo0RkVgcfM67ppVLxvXWQCJ/P5i Gz3S578C9hoYjyezC4UMU+6YP9O53K49wURLpf2znAcFuxa2t9TmXwjSy5DeMlCf QW+6p6Pn2he59ZkSMgUofVgcEiRqK+MzTYr1/0DvOSjGEaUB8i4w7k7qdsD/ZowF cS72W826AqSNA2d5BMlocRXvQH5Sq5HlSLD/K+bwKIqMI+YcAblvBkhZd/NmMcvs LRmHldJA/1KJFVy49OzpPFJYlTwt1G5zyDJYtDxR5Tx6d2Pvd6hkwMtH5PtTHxY+ 4hAwfVymIC2qa7+i2gpxTuY4huftbbwJqNK2U9fwS5nipxPKsCSzZeA6psXnbfei 6mjJ0vzOrcGpjgYhRZraesofwx7QoGNryt0XN1pHNFt6DLMmGIOx9iLDabKGV9fR oQbxJXk8Ll6CyEdsurUbyhraI0mXXz4fifU4El8jUz92rc7SpLuaSAQzYNISKWqi ucGyDLZXSPqb3YWm+8i1jUtn4oEq1tb4dp45813TLkUPyqaxAwuyDrbiBEGS4QxE RIjCZt3DAndUOMigSJNYgieLpq1SGJuRjHpPV7ZwHVEaD6f55taAddWSOBku9Smi +vrZWsnShA9qDzs+qZr/KmnQtoCP0TozyUA0aRAvk0Uv1fbIwMfjBN+spO8WPR28 MBGAgmsN7ds= =uIW8 -----END PGP SIGNATURE----- --Sig_/IEIBn21qZz3y6Slr_r+syJq--