Am Samstag, 18. Januar 2003 02:00 schrieb David Brownell:
> Oliver Neukum wrote:
> > Hi,
> >
> > regarding this piece of code:
> > spin_lock_irqsave (&ehci->lock, flags);
> > ...
> >
> > Does this mean that any call to usb_unlink_urb() for an URB on EHCI
> > with a spinlock held will fail?
>
> No, but a _synchronous_ one might need to wait_ms(1) for the relevant
> hardware resource to become available, and that wouldn't be a good
> thing with a spinlock held. (That was the line after your quote.)
But you don't check for asynchronousity, you check for in_interrupt().
This is not the same thing. In fact it means that usb_unlink_urb()
may schedule with a spinlock held, even if the asynchronous attribute
is set.
As far as I can tell, the safe code would be:
if (urb->transfer_flags | URB_ASYNC_UNLINK) {
udelay(...);
} else {
set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(...);
}
Regards
Oliver
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