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

Chris Wright
2009-12-15T23:13:58Z

* Alexander Graf (agraf@suse.de) wrote:
> Chris Wright wrote:
> > * 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.
> >
>
> Hum, yeah. I'm starting to understand why the shell was invented.

Heh

> >> + 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?
>
> What others do we have?

The above would trigger when you've already assigned the same device,
and the error message would be confusing: "The driver pci_stub
is occupying..." (btw, perhaps s/occupying your/bound to/ would be
clearer). EEXIST is used for that case. I think that's it for errors the
user could do something with.

thanks,
-chris