Messages in this thread | | | Date | Wed, 21 May 2008 10:46:45 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [PATCH] USB: fix deadlock in HCD code |
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On Wed, 21 May 2008, Jiri Kosina wrote:
> On Wed, 21 May 2008, Alan Stern wrote: > > > > Used in the suspend code. Your patch is indeed correct, but I fear > > > there might be a second bug caused by wrong calling conditions. > > The problem in the Novell bugzilla entry was caused by the fact that the > > OHCI irq routine was invoked with interrupts enabled, owing to a missing > > IRQF_DISABLED flag. That bug has already been fixed in 2.6.25. > > That indeed is 2.6.25 kernel. I guess you are talking about commit > 442258e2ff69 here.
Yes.
> If so, the reporter is definitely using the kernel > containing this commit, and the lockups still trigger. > > Seems that my patch is papering over the real bug (someone enabling > interrupts somewhere) indeed, but I can't seem to be able to find such > codepath.
You could try testing the interrupt-enable flag at various places in ohci-hcd (start with finish_urb) and printing an error message if interrupts are enabled.
One possibility is that in an earlier call to finish_urb, usb_hcd_giveback_urb was called with interrupts disabled and returned with interrupts enabled. In other words, some driver's callback routine may have enabled interrupts incorrectly.
Alan Stern
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