Re: [PATCH v2] USB: host: Use zeroing memory allocator rather than allocator/memset

[Himanshu Jha]

On Mon, Jan 01, 2018 at 10:53:07AM -0500, Alan Stern wrote:
> On Mon, 1 Jan 2018, Himanshu Jha wrote:
> 
> > On Sun, Dec 31, 2017 at 04:20:45PM -0500, Alan Stern wrote:
> > > On Sun, 31 Dec 2017, Himanshu Jha wrote:
> > > 
> > > > Use dma_zalloc_coherent for allocating zeroed
> > > > memory and remove unnecessary memset function.
> > > > 
> > > > Done using Coccinelle.
> > > > Generated-by: scripts/coccinelle/api/alloc/kzalloc-simple.cocci
> > > > 0-day tested with no failures.
> > > > 
> > > > Suggested-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
> > > > Signed-off-by: Himanshu Jha <himanshujha199640@xxxxxxxxx>
> > > > ---
> > > > v2:
> > > >    -align argumenst as they were before applying the SmPL rule.
> > > 
> > > For the UHCI portion:
> > > 
> > > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> > > 
> > > But there is something pecular about the patch...
> > > 
> > > >  drivers/usb/host/uhci-hcd.c | 7 +++----
> > > >  drivers/usb/host/xhci-mem.c | 7 ++-----
> > > >  2 files changed, 5 insertions(+), 9 deletions(-)
> > > > 
> > > > diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
> > > > index f5c9021..ac53398 100644
> > > > --- a/drivers/usb/host/uhci-hcd.c
> > > > +++ b/drivers/usb/host/uhci-hcd.c
> > > > @@ -600,15 +600,14 @@ static int uhci_start(struct usb_hcd *hcd)
> > > >  	uhci->dentry = dentry;
> > > >  #endif
> > > >  
> > > > -	uhci->frame = dma_alloc_coherent(uhci_dev(uhci),
> > > > -			UHCI_NUMFRAMES * sizeof(*uhci->frame),
> > > > -			&uhci->frame_dma_handle, GFP_KERNEL);
> > > > +	uhci->frame = dma_zalloc_coherent(uhci_dev(uhci),
> > > > +			UHCI_NUMFRAMES * sizeof(*uhci->frame),
> > > > +			&uhci->frame_dma_handle, GFP_KERNEL);
> > > 
> > > The second and third "changed" lines here actually are identical.  What 
> > > program would produce a diff file showing that they were changed?
> > 
> > I'm sorry, I can't understand the problem.
> 
> There is no problem.  I merely asked a question.
> 
> > The patch was generated by cocci script specified above and then you
> > told me to change the whitespace scheme as it was before.
> 
> Yes, I know.  But did you change the cocci script to make it produce
> this new patch, or did you make the patch by manually editing the old
> version?  In other words, how was this patch generated?

I did that manually, no change in cocci script.

Thanks
Himanshu Jha