Re: [PATCH 3/3] Inform users about busy device assignment attempt

Chris Wright
2009-12-15T20:28:57Z

* Alexander Graf (agraf@suse.de) wrote:
> +static void assign_failed_examine(AssignedDevice *dev)
> +{
> + char name[PATH_MAX], dir[PATH_MAX], driver[PATH_MAX] = {}, *ns;
> + uint16_t vendor_id, device_id;
> + int r;
> +
> + /* XXX implement multidomain */
> + sprintf(dir, "/sys/bus/pci/devices/0000:%02x:%02x.%01x/",
> + dev->host.bus, dev->host.dev, dev->host.func);
> +
> + sprintf(name, "%sdriver", dir);
> +
> + r = readlink(name, driver, sizeof(driver));
> + if ((r <= 0) || !(ns = strrchr(driver, '/')) || r >= sizeof(driver)) {

While the symlink should never be that long, I think you want to
check bytes stored in driver before strrchr, else you may walk off a
non-NULL-terminated buffer.

> + goto fail;
> + }
> +
> + ns++;
> +
> + if (get_real_vendor_id(dir, &vendor_id) ||
> + get_real_device_id(dir, &device_id)) {
> + goto fail;
> + }
> +
> + fprintf(stderr, "*** The driver '%s' is occupying your device "
> + "%02x:%02x.%x.\n",
> + ns, dev->host.bus, dev->host.dev, dev->host.func);
> + fprintf(stderr, "***\n");
> + fprintf(stderr, "*** You can try the following commands to free it:\n");
> + fprintf(stderr, "***\n");
> + fprintf(stderr, "*** $ echo \"%04x %04x\" > /sys/bus/pci/drivers/pci-stub/"
> + "new_id\n", vendor_id, device_id);
> + fprintf(stderr, "*** $ echo \"0000:%02x:%02x.%x\" > /sys/bus/pci/drivers/"
> + "%s/unbind\n",
> + dev->host.bus, dev->host.dev, dev->host.func, ns);
> + fprintf(stderr, "*** $ echo \"0000:%02x:%02x.%x\" > /sys/bus/pci/drivers/"
> + "pci-stub/bind\n",
> + dev->host.bus, dev->host.dev, dev->host.func);
> + fprintf(stderr, "*** $ echo \"%04x %04x\" > /sys/bus/pci/drivers/pci-stub"
> + "/remove_id\n", vendor_id, device_id);
> + fprintf(stderr, "***\n");
> +
> + return;
> +
> +fail:
> + fprintf(stderr, "Couldn't find out why.\n");
> +}
> +
> static int assign_device(AssignedDevice *dev)
> {
> struct kvm_assigned_pci_dev assigned_dev_data;
> @@ -781,9 +829,12 @@ static int assign_device(AssignedDevice *dev)
> #endif
>
> r = kvm_assign_pci_device(kvm_context, &assigned_dev_data);
> - if (r < 0)
> - fprintf(stderr, "Failed to assign device \"%s\" : %s\n",
> + if (r < 0) {
> + fprintf(stderr, "Failed to assign device \"%s\" : %s\n",
> dev->dev.qdev.id, strerror(-r));
> +
> + assign_failed_examine(dev);

Only really catching the EBUSY case, maybe test for explicitly?