Re: [PATCH] USB: Documentation: Update description of completion callback context

[Alan Stern]

On Thu, Oct 15, 2026 at 08:26:43PM +0200, Sebastian Andrzej Siewior wrote:
> On 2026-10-15 12:00:46 [-0400], Alan Stern wrote:
> > The existing kerneldoc documentation for URB completion callbacks is
> > incorrect about the context in which the callbacks occur; it is not
> > always in_interrupt.  State explicitly that a callback may occur in
> > any context with no guarantees, and likewise for the status of
> > CPU-local interrupts.
> > 
> > Documentation update only; no code changes.
> > 
> > Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> 
> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> 
> usb_hcd_giveback_urb() kernel doc says: 
> 
> |  * Context: atomic. The completion callback is invoked either in a work queue
> |  * (BH) context or in the caller's context, depending on whether the HCD_BH
> |  * flag is set in the @hcd structure, except that URBs submitted to the
> |  * root hub always complete in BH context.
> 
> Do you think this deserves an update?

I think that's okay as is.  It describes the current implementation 
pretty well, even though it doesn't mention the lack of guarantees.  If 
you feel it should be changed, let me know.

Alan Stern