From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vasilis Liaskovitis Subject: Re: [PATCH] ACPI / scan: Make it clear that acpi_bus_trim() cannot fail Date: Mon, 18 Feb 2013 15:53:41 +0100 Message-ID: <20130218145341.GC4448@dhcp-192-168-178-175.profitbricks.localdomain> References: <1511096.zmfmBrfdmu@vostro.rjw.lan> <20130218122549.GA4448@dhcp-192-168-178-175.profitbricks.localdomain> <15493777.FVIQvWOuf9@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-bk0-f54.google.com ([209.85.214.54]:40808 "EHLO mail-bk0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751970Ab3BROxq (ORCPT ); Mon, 18 Feb 2013 09:53:46 -0500 Received: by mail-bk0-f54.google.com with SMTP id w5so2577933bku.41 for ; Mon, 18 Feb 2013 06:53:45 -0800 (PST) Content-Disposition: inline In-Reply-To: <15493777.FVIQvWOuf9@vostro.rjw.lan> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: ACPI Devel Maling List , LKML , Bjorn Helgaas , Yinghai Lu , Toshi Kani , Jiang Liu , wency@cn.fujitsu.com On Mon, Feb 18, 2013 at 02:17:02PM +0100, Rafael J. Wysocki wrote: > On Monday, February 18, 2013 01:25:49 PM Vasilis Liaskovitis wrote: > > Hi, > > > > On Thu, Jan 24, 2013 at 11:56:50PM +0100, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki > > > > > > Since acpi_bus_trim() cannot fail, change its definition to a void > > > function, so that its callers don't check the return value in vain > > > and update the callers. > > > > I have missed a few patchsets/discussions in the last month and wanted to > > ask a question related to this: Does the new always-succeed 2-pass > > trim_device design guarantee safe memory hot-remove operations? > > I doesn't by itself. Nor it really can, because the .remove() callbacks of > device drivers are not allowed to fail. right. > > > Afaict if memory offline fails now, the device is ejected (_EJ0) anyways > > causing a panic. Tested in a VM with linux-next-20130207 and > > linux-next-20130218 by doing an SCI-eject request on a hot-plugged dimm. > > > > Are there more patches in development for safe memory hot-remove? > > Yes, there are. I sent a patch series yesterday introducing some safety > measures (you can disable memory hotplug from user space or disable > automatic ejection). There's more to come still. > > The plan is to introduce offline/online operations for memory modules (in > analogy with CPU core online/offline) that can be started by user space and > memory eject will only be possible after offline (i.e. when the memory module > is known to be not in use). ok, thanks for the info. I 'll test these and the follow ups. thanks again, - Vasilis