From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [RFC PATCH v2 0/3] acpi: Introduce prepare_remove device operation Date: Fri, 16 Nov 2012 15:01:43 -0800 Message-ID: <20121116230143.GA15338@kroah.com> References: <1352974970-6643-1-git-send-email-vasilis.liaskovitis@profitbricks.com> <1446291.TgLDtXqY7q@vostro.rjw.lan> <1353105943.12509.60.camel@misato.fc.hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:51707 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753454Ab2KPXBr (ORCPT ); Fri, 16 Nov 2012 18:01:47 -0500 Received: by mail-pa0-f46.google.com with SMTP id hz1so2165611pad.19 for ; Fri, 16 Nov 2012 15:01:47 -0800 (PST) Content-Disposition: inline In-Reply-To: <1353105943.12509.60.camel@misato.fc.hp.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Toshi Kani Cc: "Rafael J. Wysocki" , Vasilis Liaskovitis , linux-acpi@vger.kernel.org, isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com, lenb@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, Nov 16, 2012 at 03:45:43PM -0700, Toshi Kani wrote: > On Fri, 2012-11-16 at 22:43 +0100, Rafael J. Wysocki wrote: > > On Thursday, November 15, 2012 11:22:47 AM Vasilis Liaskovitis wrote: > > > As discussed in https://patchwork.kernel.org/patch/1581581/ > > > the driver core remove function needs to always succeed. This means we need > > > to know that the device can be successfully removed before acpi_bus_trim / > > > acpi_bus_hot_remove_device are called. This can cause panics when OSPM-initiated > > > eject or driver unbind of memory devices fails e.g with: > > > > > > echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject > > > echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind > > > > > > since the ACPI core goes ahead and ejects the device regardless of whether the > > > the memory is still in use or not. > > > > So the question is, does the ACPI core have to do that and if so, then why? > > The problem is that acpi_memory_devcie_remove() can fail. However, > device_release_driver() is a void function, so it cannot report its > error. Here are function flows for SCI, sysfs eject and unbind. Then don't ever let acpi_memory_device_remove() fail. If the user wants it gone, it needs to go away. Just like any other device in the system that can go away at any point in time, you can't "fail" that. greg k-h