Re: [PATCH] USB: fix deadlock in HCD code

[Jiri Kosina]

On Wed, 21 May 2008, Oliver Neukum wrote:

> > hcd_urb_list_lock is used for synchronization between IRQ and non-IRQ 
> > contexts, so the non-IRQ context has to disable IRQs in order to prevent 
> > deadlocking with IRQ context.
> Which non-irq context is that?

One example -- assume usb_submit_urb() called from non-IRQ context. Then

usb_hcd_submit_urb() -> rh_urb_enqueue() -> rh_queue_status() -> 
usb_hcd_link_urb_to_ep().

-- 
Jiri Kosina
SUSE Labs
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