From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756603AbZCJWhk (ORCPT ); Tue, 10 Mar 2009 18:37:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755174AbZCJWha (ORCPT ); Tue, 10 Mar 2009 18:37:30 -0400 Received: from g4t0017.houston.hp.com ([15.201.24.20]:9087 "EHLO g4t0017.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754162AbZCJWh3 (ORCPT ); Tue, 10 Mar 2009 18:37:29 -0400 Date: Tue, 10 Mar 2009 16:37:27 -0600 From: Alex Chiang To: jbarnes@virtuousgeek.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, djwong@us.ibm.com, vegard.nossum@gmail.com, Trent Piepho Subject: Re: [PATCH v3 07/11] PCI: Introduce /sys/bus/pci/devices/.../remove Message-ID: <20090310223727.GA25665@ldl.fc.hp.com> Mail-Followup-To: Alex Chiang , jbarnes@virtuousgeek.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, djwong@us.ibm.com, vegard.nossum@gmail.com, Trent Piepho References: <20090309052933.3918.86601.stgit@bob.kio> <20090309054911.3918.91600.stgit@bob.kio> <20090309185255.GK32589@ldl.fc.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090309185255.GK32589@ldl.fc.hp.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Alex Chiang : > This is an updated version of this patch. It fixes a bug where we > would remove a bridge even if it still had children. > > Now we check for children before attempting to remove the bridge. This is another updated version of the patch. It adds a mutex for the sysfs callback function. This mutex, along with another sysfs patch that I plan on posting soon, should help prevent an oops that a crazy user might induce with the following loop: # while true ; do echo 1 > /sys/bus/pci/devices/.../remove ; done I'm posting this updated version so that Vegard can drop it into his test setup that he had. When I post v4 of this entire patch series, I'll have a full changelog, etc. Thanks. /ac commit 53cb428d7a26be7b3ea38f6d7f30cd33cc1e6b4a Author: Alex Chiang Date: Tue Mar 10 16:32:45 2009 -0600 PCI: Introduce /sys/bus/pci/devices/.../remove This patch adds an attribute named "remove" to a PCI device's sysfs directory. Writing a non-zero value to this attribute will remove the PCI device and any children of it. Trent Piepho wrote the original implementation and documentation. Cc: djwong@us.ibm.com Cc: Trent Piepho Signed-off-by: Alex Chiang diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index ea4aee2..5b1ddde 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -50,6 +50,14 @@ Description: re-discover previously removed devices. Depends on CONFIG_HOTPLUG. +What: /sys/bus/pci/devices/.../remove +Date: January 2009 +Contact: Linux PCI developers +Description: + Writing a non-zero value to this attribute will + hot-remove the PCI device and any of its children. + Depends on CONFIG_HOTPLUG. + What: /sys/bus/pci/devices/.../vpd Date: February 2008 Contact: Ben Hutchings diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt index 9f8740c..26e4b8b 100644 --- a/Documentation/filesystems/sysfs-pci.txt +++ b/Documentation/filesystems/sysfs-pci.txt @@ -12,6 +12,7 @@ that support it. For example, a given bus might look like this: | |-- enable | |-- irq | |-- local_cpus + | |-- remove | |-- resource | |-- resource0 | |-- resource1 @@ -36,6 +37,7 @@ files, each with their own function. enable Whether the device is enabled (ascii, rw) irq IRQ number (ascii, ro) local_cpus nearby CPU mask (cpumask, ro) + remove remove device from kernel's list (ascii, wo) resource PCI resource host addresses (ascii, ro) resource0..N PCI resource N, if present (binary, mmap) resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap) @@ -46,6 +48,7 @@ files, each with their own function. ro - read only file rw - file is readable and writable + wo - write only file mmap - file is mmapable ascii - file contains ascii text binary - file contains binary data @@ -73,6 +76,13 @@ that the device must be enabled for a rom read to return data succesfully. In the event a driver is not bound to the device, it can be enabled using the 'enable' file, documented above. +The 'remove' file is used to remove the PCI device, by writing a non-zero +integer to the file. This does not involve any kind of hot-plug functionality, +e.g. powering off the device. The device is removed from the kernel's list of +PCI devices, the sysfs directory for it is removed, and the device will be +removed from any drivers attached to it. Removal of PCI root buses is +disallowed. + Accessing legacy resources through sysfs ---------------------------------------- diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index a29fc3b..11bc9b1 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -219,6 +219,51 @@ msi_bus_store(struct device *dev, struct device_attribute *attr, return count; } +#ifdef CONFIG_HOTPLUG +static DEFINE_MUTEX(pci_remove_mutex); +static void remove_callback(struct device *dev) +{ + int bridge = 0; + struct pci_dev *pdev = to_pci_dev(dev); + + mutex_lock(&pci_remove_mutex); + + if (pdev->subordinate) + bridge = 1; + + pci_remove_bus_device(pdev); + if (bridge && list_empty(&pdev->bus->devices)) + pci_remove_bus(pdev->bus); + pci_dev_put(pdev); + + mutex_unlock(&pci_remove_mutex); +} + +static ssize_t +remove_store(struct device *dev, struct device_attribute *dummy, + const char *buf, size_t count) +{ + int ret = 0; + unsigned long val; + struct pci_dev *pdev = to_pci_dev(dev); + + if (strict_strtoul(buf, 0, &val) < 0) + return -EINVAL; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (pdev->subordinate && pci_is_root_bus(pdev->bus)) + return -EBUSY; + + if (val) + ret = device_schedule_callback(dev, remove_callback); + if (ret) + count = ret; + return count; +} +#endif + struct device_attribute pci_dev_attrs[] = { __ATTR_RO(resource), __ATTR_RO(vendor), @@ -237,6 +282,9 @@ struct device_attribute pci_dev_attrs[] = { __ATTR(broken_parity_status,(S_IRUGO|S_IWUSR), broken_parity_status_show,broken_parity_status_store), __ATTR(msi_bus, 0644, msi_bus_show, msi_bus_store), +#ifdef CONFIG_HOTPLUG + __ATTR(remove, S_IWUSR, NULL, remove_store), +#endif __ATTR_NULL, };