Messages in this thread | | | Date | Tue, 5 Jun 2012 17:38:39 +0800 | Subject | Re: [PATCH] driver core: fix shutdown races with probe/remove | From | Ming Lei <> |
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Hi,
On Tue, Jun 5, 2012 at 5:18 PM, Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > On Tue, Jun 05, 2012 at 04:59:07PM +0800, Ming Lei wrote: >> Firstly, .shutdown callback may touch a uninitialized hardware >> if dev->driver is set and .probe is not completed. > > When would that ever happen?
It may happen when someone plugs a device, then run 'shutdown' immediately.
> >> Secondly, device_shutdown() may dereference a null pointer to cause >> oops when dev->driver is cleared after it is checked in device_shutdown(). > > Again, when would that happen? A new device/driver being added to the > system as it is being shutdown?
It is usually that someone presses 'power off' button and unplugs its usb devices or pci/e devices, maybe together with a new plug.
In such case, the oops may be triggered.
> > Has anyone ever hit that before?
Looks someone has reported it, I also can trigger it with some delay added in device_shutdown.
> > Is this really needed?
In case that it is triggered, oops will prevent system from being shutdown, and it should be a big problem.
IMO, we can avoid it without much change and side effect, so looks worthy the change.
Thanks, -- Ming Lei -- 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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