From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH v2] wait while adding MMC host to ensure root mounts Date: Sat, 13 Apr 2013 08:52:21 -0400 Message-ID: <8738uubnju.fsf@octavius.laptop.org> References: <1363223183-3772-1-git-send-email-ynvich@gmail.com> <1363224194-7366-1-git-send-email-ynvich@gmail.com> <87620jmkoe.fsf@octavius.laptop.org> <87ppylf429.fsf@octavius.laptop.org> <1365850153.9806.59.camel@host5.omatika.ru> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from void.printf.net ([89.145.121.20]:40412 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753142Ab3DMMw2 (ORCPT ); Sat, 13 Apr 2013 08:52:28 -0400 In-Reply-To: <1365850153.9806.59.camel@host5.omatika.ru> (Sergey Yanovich's message of "Sat, 13 Apr 2013 14:49:13 +0400") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Sergey Yanovich Cc: Ulf Hansson , Greg Kroah-Hartman , Linus Walleij , Jaehoon Chung , Namjae Jeon , linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org Hi, On Sat, Apr 13 2013, Sergey Yanovich wrote: > On Wed, 2013-03-27 at 07:57 -0400, Chris Ball wrote: >> If the delay's significant, I agree with you and will revert this patch. > > The patch was reverted. The problem is back. Filed bug: > https://bugzilla.kernel.org/show_bug.cgi?id=56561 > > A possible solution is to make card a separate device (now only the host > is a device). In this case, the probing could be done asynchronously > without breaking the assumption in prepare_namespace(). > > Chris, could you comment? The same problem (of requiring rootwait) exists when trying to boot from a SCSI/USB device, so I don't think there's any MMC-specific problem here. Most people who aren't using an initrd have to supply rootwait. I liked the idea behind your patch, but the performance regression isn't acceptable. If we can't find a way to conditionalize the call to mmc_flush_scheduled_work() on being in a situation where we're definitely about to panic, I think the only option would be to try to come up with a solution at the layers above MMC. Thanks, - Chris. -- Chris Ball One Laptop Per Child