[PATCH] usb: gadget: aspeed_udc: fix handling of tx_len == 0

[Dan Carpenter]

On Thu, Jun 23, 2022 at 07:52:28AM +0000, Neal Liu wrote:
> > On Thu, Jun 23, 2022 at 09:43:20AM +0300, Dan Carpenter wrote:
> > > On Thu, Jun 23, 2022 at 01:41:49AM +0000, Neal Liu wrote:
> > > > > The bug is that we should still enter this loop if "tx_len" is zero.
> > > > >
> > > > > After adding the "last" variable, then the "chunk >= 0" condition
> > > > > is no longer required but I left it for readability.
> > > > >
> > > >
> > > > Use either "chunk >=0" or "last".
> > > > I think the former is more simpler.
> > >
> > > chunk >= 0 doesn't work.  last works but I think this way is more
> > > readable.
> > 
> > Fine, I can remove the chunk >= 0.  But you can see why your idea of
> > removing the "last" doesn't work, right?  I mean maybe it does work and
> > there was a bug in the original code?  Could you please look at that so we're
> > for sure writing correct code?
> > 
> 
> Why removing the "last" doesn't work? If "chunk == 0", it would go through while loop once, and chunk will be negative (chunk -= ep->chunk_max).
> 

chunk -= ep->chunk_max could set chunk to zero.

regards,
dan carpenter