Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757808AbYFGT6N (ORCPT ); Sat, 7 Jun 2008 15:58:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752974AbYFGT56 (ORCPT ); Sat, 7 Jun 2008 15:57:58 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:1576 "EHLO spitz.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753177AbYFGT55 (ORCPT ); Sat, 7 Jun 2008 15:57:57 -0400 Date: Sat, 7 Jun 2008 21:52:22 +0200 From: Pavel Machek To: Alan Stern , Linus Torvalds Cc: gregkh@suse.de, Andrew Morton , kernel list , Oliver Neukum Subject: Re: 2.6.25-rc6: CONFIG_USB_PERSIST forced on Message-ID: <20080607195221.GB11109@ucw.cz> References: <20080606092546.GA2596@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2209 Lines: 57 On Fri 2008-06-06 10:39:19, Alan Stern wrote: > On Fri, 6 Jun 2008, Pavel Machek wrote: > > > Hi! > > > > In 2.6.26-rc5, > > > > -config USB_PERSIST > > - bool "USB device persistence during system suspend (DANGEROUS)" > > > > is now on. Given that it was previously marked "DANGEROUS", that seems > > quite a change to me. > > It is. Basically I did it because Linus asked for it -- or at least, > for something like it. He felt that the danger of not having > USB_PERSIST when you need it is worse than the danger of having it when > you don't want it. Well, not-usb-persists means we force-unplug disks during suspend, after syncing them. Not _too_ bad. If you unplug disk while hibernated, modify it, and plug it back, youget _silent_ filesystem corruption. I call that bad. > > Besides, it seems to have broken usblp hibernation support, and maybe > > other devices that does not have reset_resume() present. (Big thanks > > for Oliver for doing investigation). > > URL? It's hard to see how lack of reset-resume support would mess > anything up worse than it would be without USB_PERSIST. usblp driver sets 'suspended' flag in .suspend(), and resets it in .resume() -- except that with USB_PERSIST .resume() is not called :-(. I have novell bugzilla bug number somewhere... > > [Or is it that now USB_PERSIST is conditional on /sys fs setting, so > > while setting it on individual device is dangerous, it is still N by > > default? Changelog does not tell me...?] > > USB_PERSIST is (and has always been) conditional on the power/persist > sysfs attribute setting. The difference is that now the setting starts > out as On whereas before it started out as Off, and there no longer is > a Kconfig option to remove USB_PERSIST entirely. I consider the default to be dangerous here. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/