Messages in this thread Patch in this message | | | Subject | Re: Add a "enable" sysfs attribute to the pci devices to allow userspace (Xorg) to enable devices without doing foul direct access | From | Arjan van de Ven <> | Date | Sat, 29 Apr 2006 10:59:08 +0200 |
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> > + if (!pdev) > > + return 1; > > Can this happen?
eh I suppose not; the other code doesn't check it either; fixed
> > > + /* this can crash the machine when done on the "wrong" device */ > > + if (!capable(CAP_SYS_ADMIN)) > > + return 1; > > Don't the file's permissions suffice?
that's a more philosophical question; you can ask that question about the entire capability system ;) Other code in the same file uses this same capability for a same level of access though.
> return count; > fixed
ok new patch below
This patch adds an "enable" sysfs attribute to each PCI device. When read it shows the "enabled-ness" of the device, but you can write a "0" into it to disable a device, and a "1" to enable it.
This later is needed for X and other cases where userspace wants to enable the BARs on a device (typical example: to run the video bios on a secundary head). Right now X does all this "by hand" via bitbanging, that's just evil. This allows X to no longer do that but to just let the kernel do this.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> CC: Peter Jones <pjones@redhat.com> CC: Dave Airlie <airlied@linux.ie> --- drivers/pci/pci-sysfs.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
Index: linux-2.6.17-rc2-enable/drivers/pci/pci-sysfs.c =================================================================== --- linux-2.6.17-rc2-enable.orig/drivers/pci/pci-sysfs.c +++ linux-2.6.17-rc2-enable/drivers/pci/pci-sysfs.c @@ -43,6 +43,7 @@ pci_config_attr(subsystem_vendor, "0x%04 pci_config_attr(subsystem_device, "0x%04x\n"); pci_config_attr(class, "0x%06x\n"); pci_config_attr(irq, "%u\n"); +pci_config_attr(is_enabled, "%u\n"); static ssize_t local_cpus_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -90,6 +91,25 @@ static ssize_t modalias_show(struct devi (u8)(pci_dev->class >> 16), (u8)(pci_dev->class >> 8), (u8)(pci_dev->class)); } +static ssize_t +is_enabled_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct pci_dev *pdev = to_pci_dev(dev); + + /* this can crash the machine when done on the "wrong" device */ + if (!capable(CAP_SYS_ADMIN)) + return count; + + if (*buf == '0') + pci_disable_device(pdev); + + if (*buf == '1') + pci_enable_device(pdev); + + return count; +} + struct device_attribute pci_dev_attrs[] = { __ATTR_RO(resource), @@ -101,6 +121,7 @@ struct device_attribute pci_dev_attrs[] __ATTR_RO(irq), __ATTR_RO(local_cpus), __ATTR_RO(modalias), + __ATTR(enable, 0600, is_enabled_show, is_enabled_store), __ATTR_NULL, }; - 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/
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