Messages in this thread | | | Date | Thu, 19 Mar 2009 23:17:50 +0900 | From | Kenji Kaneshige <> | Subject | Re: [PATCH v4 08/12] PCI: Introduce /sys/bus/pci/devices/.../remove |
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Alex Chiang wrote: > 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> > Signed-off-by: Alex Chiang <achiang@hp.com> > --- > > Documentation/ABI/testing/sysfs-bus-pci | 8 ++++++ > Documentation/filesystems/sysfs-pci.txt | 10 +++++++ > drivers/pci/pci-sysfs.c | 44 +++++++++++++++++++++++++++++++ > 3 files changed, 62 insertions(+), 0 deletions(-) > > 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 <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> > 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 22dbc65..6e2b1fd 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -246,6 +246,47 @@ struct bus_attribute pci_bus_attrs[] = { > __ATTR(rescan, S_IWUSR, NULL, bus_rescan_store), > __ATTR_NULL > }; > + > +static void remove_callback(struct device *dev) > +{ > + int bridge = 0; > + struct pci_dev *pdev = to_pci_dev(dev); > + > + mutex_lock(&pci_remove_rescan_mutex); > + > + if (pdev->subordinate) > + bridge = 1; > + > + pci_remove_bus_device(pdev); > + if (bridge && list_empty(&pdev->bus->devices)) > + pci_remove_bus(pdev->bus);
I cannot understand the above two lines. Could you explain what it intend?
Thanks, Kenji Kaneshige
> + > + 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 (!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[] = { > @@ -266,6 +307,9 @@ 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, > }; > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > >
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