Messages in this thread | | | Date | Thu, 23 Feb 2006 22:32:42 -0500 (EST) | From | Alan Stern <> | Subject | Re: [PATCH] driver core: better reference counting for klists |
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On Thu, 23 Feb 2006, Greg KH wrote:
> On Thu, Feb 23, 2006 at 10:38:13AM -0500, Alan Stern wrote: > > On Wed, 22 Feb 2006, Greg KH wrote: > > > > > > Index: usb-2.6/drivers/base/dd.c > > > > =================================================================== > > > > --- usb-2.6.orig/drivers/base/dd.c > > > > +++ usb-2.6/drivers/base/dd.c > > > > @@ -72,6 +72,8 @@ int driver_probe_device(struct device_dr > > > > { > > > > int ret = 0; > > > > > > > > + if (!device_is_registered(dev)) > > > > + return -ENODEV; > > > > if (drv->bus->match && !drv->bus->match(dev, drv)) > > > > goto Done; > > > > > > > > Index: usb-2.6/drivers/base/bus.c > > > > =================================================================== > > > > --- usb-2.6.orig/drivers/base/bus.c > > > > +++ usb-2.6/drivers/base/bus.c > > > > @@ -367,6 +367,7 @@ int bus_add_device(struct device * dev) > > > > > > > > if (bus) { > > > > pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id); > > > > + dev->is_registered = 1; > > > > device_attach(dev); > > > > klist_add_tail(&dev->knode_bus, &bus->klist_devices); > > > > error = device_add_attrs(bus, dev); > > > > @@ -393,7 +394,8 @@ void bus_remove_device(struct device * d > > > > sysfs_remove_link(&dev->kobj, "bus"); > > > > sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id); > > > > device_remove_attrs(dev->bus, dev); > > > > - klist_remove(&dev->knode_bus); > > > > + klist_del(&dev->knode_bus); > > > > + dev->is_registered = 0; > > > > > > Don't we have a race between these two lines? How is that protected?
> The last 2 ones above, doing a klist_del() and then after that setting > is_registered to 0.
I don't understand the question. The two lines are part of the same routine and they run in the same thread, so how can one race the other?
Alan Stern
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