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SubjectRe: [PATCH 0/5] V2 usb console improvements series
On Wed, 17 Mar 2010, Jason Wessel wrote:

> On 03/17/2010 09:30 AM, Alan Stern wrote:
> > On Tue, 16 Mar 2010, Jason Wessel wrote:
> >
> >
> >> Part of having the console stable requires that usb sysrq handler get
> >> executed in a tasklet. The hcd device lock is always held while the
> >> driver call backs are executed. The means you cannot get the sysrq
> >> printk's out to the usb console device after the in_flight urb queue
> >> is filled.
> >>
> >
> > Either I don't understand this comment properly or else it is simply
> > wrong. HCDs do not continue to hold their locks when handing completed
> > URBs back to drivers. The giveback call occurs with interrupts
> > disabled, but no locks are held.
> >
> >
>
> The call back from the urb processing holds a lock.

Which callback and which lock, exactly? Surely not the "hcd device
lock" as your description says, and maybe not the "driver call back".

Alan Stern



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