Fix memory issue in non-DMA mode for MUSB gadget

[Bin Liu <b-liu@ti.com>]

Hi,

Please don't top-posting.

On Fri, Aug 03, 2018 at 06:25:50AM +0000, Alexey Spirkov wrote:
> Hi, Bin,
> 
> Thanks for note, but what do you think - is 'dma_mapping_error'
> checking still needed before call of unmap_dma_buffer? If yes than
> I'll check DMA usage in this check instead of is_buffer_map.

No, unmap_dma_buffer() can be called unconditionally here because
unmap_dma_buffer() already calls is_buffer_mapped() internally.

So my comment below is to remove the 'if' condition check you modified.

Regards,
-Bin.

> 
> Best regards,
> Alexey Spirkov
> 
> -----Original Message-----
> From: Bin Liu <b-liu@ti.com> 
> Sent: Thursday, August 2, 2018 7:15 PM
> To: Alexey Spirkov <AlexeiS@astrosoft.ru>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; linux-usb@vger.kernel.org; andrew@ncrmnt.org
> Subject: Re: [PATCH] Fix memory issue in non-DMA mode for MUSB gadget
> 
> Hi,
> 
> On Thu, Jul 26, 2018 at 12:52:57PM +0000, Alexey Spirkov wrote:
> > dma_mapping_error function unable to works in PowerPC arch when MUSB 
> > do not use DMA (illegal memory access). Proposed patch replace its 
> > usage to usual define for checking DMA mapping.
> > 
> > Signed-off-by: Alexey Spirkov <alexeis@astrosoft.ru>
> > ---
> >  drivers/usb/musb/musb_gadget.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/musb/musb_gadget.c 
> > b/drivers/usb/musb/musb_gadget.c index eae8b1b..3bc7c25 100644
> > --- a/drivers/usb/musb/musb_gadget.c
> > +++ b/drivers/usb/musb/musb_gadget.c
> > @@ -140,7 +140,7 @@ __acquires(ep->musb->lock)
> >  	ep->busy = 1;
> >  	spin_unlock(&musb->lock);
> >  
> > -	if (!dma_mapping_error(&musb->g.dev, request->dma))
> > +	if (req && is_buffer_mapped(req))
> 
> unmap_dma_buffer() checks for is_buffer_mapped(), so this line can be dropped.
> 
> >  		unmap_dma_buffer(req, musb);
> >  
> >  	trace_musb_req_gb(req);
> 
> Regards,
> -Bin.
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