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Commit 77c27c7b authored by Alex Chiang's avatar Alex Chiang Committed by Jesse Barnes
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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.

Thanks to Vegard Nossum for testing under kmemcheck and finding locking
issues with the sysfs interface.

Cc: Trent Piepho <xyzzy@speakeasy.org>
Tested-by: default avatarVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: default avatarAlex Chiang <achiang@hp.com>
Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
parent 705b1aaa

Documentation/ABI/testing/sysfs-bus-pci

+8 −0
Original line number Diff line number Diff line
@@ -66,6 +66,14 @@ Description: 
		re-discover previously removed devices.

		Depends on CONFIG_HOTPLUG.



What:		/sys/bus/pci/devices/.../remove

Date:		January 2009

Contact:	Linux PCI developers <linux-pci@vger.kernel.org>

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 <bhutchings@solarflare.com>

Documentation/filesystems/sysfs-pci.txt

+10 −0
Original line number Diff line number Diff line
@@ -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

----------------------------------------

drivers/pci/pci-sysfs.c

+36 −0
Original line number Diff line number Diff line
@@ -243,6 +243,39 @@ struct bus_attribute pci_bus_attrs[] = { 
	__ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, bus_rescan_store),

	__ATTR_NULL

};



static void remove_callback(struct device *dev)

{

	struct pci_dev *pdev = to_pci_dev(dev);



	mutex_lock(&pci_remove_rescan_mutex);

	pci_remove_bus_device(pdev);

	mutex_unlock(&pci_remove_rescan_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 (pci_is_root_bus(pdev->bus))

		return -EBUSY;



	/* An attribute cannot be unregistered by one of its own methods,

	 * so we have to use this roundabout approach.

	 */

	if (val)

		ret = device_schedule_callback(dev, remove_callback);

	if (ret)

		count = ret;

	return count;

}

#endif



struct device_attribute pci_dev_attrs[] = {
@@ -263,6 +296,9 @@ 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|S_IWGRP), NULL, remove_store),

#endif

	__ATTR_NULL,

};