Re: [PATCH 1/3] PCI: Method for removing PCI devices

Alex Chiang
2009-02-10T22:25:00Z

* Trent Piepho <xyzzy@speakeasy.org>:
> 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.
> ---
> Documentation/filesystems/sysfs-pci.txt | 9 +++++++++
> drivers/pci/pci-sysfs.c | 26 ++++++++++++++++++++++++++
> 2 files changed, 35 insertions(+), 0 deletions(-)

I've fold this almost verbatim into my patch series, changing the
patch title, adding ABI documentation, and protecting the remove
calls with #ifdef CONFIG_HOTPLUG:

Otherwise, it's untouched.

Author: Trent Piepho <xyzzy@speakeasy.org>
Date: Tue Feb 10 15:02:54 2009 -0700

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.

[achiang@hp.com: document in Documentation/ABI]
[achiang@hp.com: add #ifdef CONFIG_HOTPLUG]
Cc: djwong@us.ibm.com
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Alex Chiang <achiang@hp.com>

Thanks.

/ac

> diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
> index 68ef488..54e014f 100644
> --- a/Documentation/filesystems/sysfs-pci.txt
> +++ b/Documentation/filesystems/sysfs-pci.txt
> @@ -11,6 +11,7 @@ that support it. For example, a given bus might look like this:
> | |-- device
> | |-- irq
> | |-- local_cpus
> + | |-- remove
> | |-- resource
> | |-- resource0
> | |-- resource1
> @@ -34,6 +35,7 @@ files, each with their own function.
> device PCI device (ascii, ro)
> 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)
> @@ -44,6 +46,7 @@ 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
> @@ -62,6 +65,12 @@ ROM file, if available. It's disabled by default, however, so applications
> should write the string "1" to the file to enable it before attempting a read
> call, and disable it following the access by writing "0" to the file.
>
> +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 removed, and the device will be removed
> +from any drivers attached to it.
> +
> Accessing legacy resources through sysfs
> ----------------------------------------
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index 3ddee7f..d422f37 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -219,6 +219,31 @@ msi_bus_store(struct device *dev, struct device_attribute *attr,
> return count;
> }
>
> +static void remove_callback(void *data)
> +{
> + pci_remove_bus_device((struct pci_dev *)data);
> +}
> +
> +static ssize_t
> +remove_store(struct device *dev, struct device_attribute *dummy,
> + const char *buf, size_t count)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> + unsigned long val;
> +
> + if (strict_strtoul(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + if (val)
> + sysfs_schedule_callback(&dev->kobj, remove_callback, pdev,
> + THIS_MODULE);
> +
> + return count;
> +}
> +
> struct device_attribute pci_dev_attrs[] = {
> __ATTR_RO(resource),
> __ATTR_RO(vendor),
> @@ -237,6 +262,7 @@ 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),
> + __ATTR(remove, S_IWUSR, NULL, remove_store),
> __ATTR_NULL,
> };
>
> --
> 1.5.4.3
>