Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [BUG] usb_set_device_state | Date | Sun, 6 Feb 2011 13:03:13 +0100 |
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On Sunday, February 06, 2011, Rafael J. Wysocki wrote: > On Sunday, February 06, 2011, Alan Stern wrote: > > On Sun, 6 Feb 2011, Rafael J. Wysocki wrote: > > > > > On Saturday, February 05, 2011, Alan Stern wrote: > > > > On Sun, 6 Feb 2011, Minchan Kim wrote: > > > > > > > > > I got following message during booting mmotm-02-04. > > ... > > > > > It seems usb_set_device_state disable irq by spin_lock_irqsave. > > > > > But it calls device_set_wakeup_capable which ends up calling sysfs_merge_group. > > > > > It calls mutex_lock. :( > > > > > > > > > > Is it already known BUG? > > > > > > > > No, it was newly introduced by changes to the > > > > device_set_wakeup_capable() routine. Rafael, this sort of problem may > > > > occur in other places too, since previously there was no requirement > > > > that device_set_wakeup_capable() be called in process context. > > > > > > I'm aware of that, but it's only happend in a handful of network drivers so far. > > > > > > I think this is a new case in -mm, though, isn't it? > > > > I'm not sure. The USB core does call device_set_wakeup_capable() > > while holding one or more spinlocks in usb_set_device_state(), and that > > routine is called in several places. You ought to be able to duplicate > > the error on your own system simply by plugging in a USB hub. > > No, I'm not. At least not with 2.6.37. > > Also, I think the problem would have been reported before if it had been that > easy to reproduce with the mainline kernel.
Or do I need to enable a specific CONFIG_ option to reproduce it?
Rafael
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