Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756088Ab2KWRux (ORCPT ); Fri, 23 Nov 2012 12:50:53 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:60385 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755931Ab2KWRuw (ORCPT ); Fri, 23 Nov 2012 12:50:52 -0500 From: Vasilis Liaskovitis To: linux-acpi@vger.kernel.org, isimatu.yasuaki@jp.fujitsu.com, wency@cn.fujitsu.com Cc: rjw@sisk.pl, lenb@kernel.org, toshi.kani@hp.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Vasilis Liaskovitis Subject: [RFC PATCH v3 3/3] acpi_memhotplug: Allow eject to proceed on rebind scenario Date: Fri, 23 Nov 2012 18:50:37 +0100 Message-Id: <1353693037-21704-4-git-send-email-vasilis.liaskovitis@profitbricks.com> X-Mailer: git-send-email 1.7.9 In-Reply-To: <1353693037-21704-1-git-send-email-vasilis.liaskovitis@profitbricks.com> References: <1353693037-21704-1-git-send-email-vasilis.liaskovitis@profitbricks.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2255 Lines: 58 Consider the following sequence of operations for a hotplugged memory device: 1. echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind 2. echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/bind 3. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject The driver is successfully re-bound to the device in step 2. However step 3 will not attempt to remove the memory. This is because the acpi_memory_info enabled bit for the newly bound driver has not been set to 1. This bit needs to be set in the case where the memory is already used by the kernel (add_memory returns -EEXIST) Setting the enabled bit in this case (in acpi_memory_enable_device) makes the driver function properly after a rebind of the driver i.e. eject operation attempts to remove memory after a successful rebind. I am not sure if this breaks some other usage of the enabled bit (see commit 65479472). When is it possible for the memory to be in use by the kernel but not managed by the acpi driver, apart from a driver unbind scenario? Perhaps the patch is not needed, depending on expected semantics of re-binding. Is the newly bound driver supposed to manage the device, if it was earlier managed by the same driver? This patch is only specific to this scenario, and can be dropped from the patch series if needed. Signed-off-by: Vasilis Liaskovitis --- drivers/acpi/acpi_memhotplug.c | 3 +-- 1 files changed, 1 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c index d0cfbd9..0562cb4 100644 --- a/drivers/acpi/acpi_memhotplug.c +++ b/drivers/acpi/acpi_memhotplug.c @@ -271,12 +271,11 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device) continue; } - if (!result) - info->enabled = 1; /* * Add num_enable even if add_memory() returns -EEXIST, so the * device is bound to this driver. */ + info->enabled = 1; num_enabled++; } if (!num_enabled) { -- 1.7.9 -- 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/