Re: [PATCH] fs: kill unused ret2 argument from iocb->ki_complete()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Oct 20, 2021 at 11:35:27AM -0600, Jens Axboe wrote:
> On 10/20/21 11:30 AM, Christoph Hellwig wrote:
> > On Wed, Oct 20, 2021 at 10:49:07AM -0600, Jens Axboe wrote:
> >> It's not used for anything, and we're wasting time passing in zeroes
> >> where we could just ignore it instead. Update all ki_complete users in
> >> the kernel to drop that last argument.
> >>
> >> The exception is the USB gadget code, which passes in non-zero. But
> >> since nobody every looks at ret2, it's still pointless.
> > 
> > Yes, the USB gadget passes non-zero, and aio passes that on to
> > userspace.  So this is an ABI change.  Does it actually matter?
> > I don't know, but you could CC the relevant maintainers and list
> > to try to figure that out.
> 
> True, guess it does go out to userspace. Greg, is anyone using
> it on the userspace side?

I really do not know (adding linux-usb@vger)  My interactions with the
gadget code have not been through the aio api, thankfully :)

Odds are it's fine, I think that something had to be passed in there so
that was chosen?  If the aio code didn't do anything with it, I can't
see where the gadget code gets it back at anywhere, but I might be
looking in the wrong place.

Anyone else here know?

thanks,

greg k-h