netdev - Re: [PATCH net] gve: fix dma sync bug where not all pages synced

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Message-ID: <CAHOA=qyWOz+2FK3F7W_eL2geALXo8s49Zjq9z6O+dwheq8jf5g@mail.gmail.com>
Date:   Mon, 18 Nov 2019 15:43:32 -0800
From:   Adi Suresh <adisuresh@...gle.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     netdev@...r.kernel.org, Catherine Sullivan <csully@...gle.com>
Subject: Re: [PATCH net] gve: fix dma sync bug where not all pages synced

On Mon, Nov 18, 2019 at 3:19 PM Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
>
> On Mon, 18 Nov 2019 14:36:30 -0800, Adi Suresh wrote:
> > The previous commit "Fixes DMA synchronization" had a bug where the
>
> Please use the standard way of quoting commits.
>
> > last page in the memory range could not be synced. This change fixes
> > the behavior so that all the required pages are synced.
> >
>
> Please add a Fixes tag.
>
> > Signed-off-by: Adi Suresh <adisuresh@...gle.com>
> > Reviewed-by: Catherine Sullivan <csully@...gle.com>
> > ---
> >  drivers/net/ethernet/google/gve/gve_tx.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/google/gve/gve_tx.c b/drivers/net/ethernet/google/gve/gve_tx.c
> > index 0a9a7ee2a866..89271380bbfd 100644
> > --- a/drivers/net/ethernet/google/gve/gve_tx.c
> > +++ b/drivers/net/ethernet/google/gve/gve_tx.c
> > @@ -393,12 +393,12 @@ static void gve_tx_fill_seg_desc(union gve_tx_desc *seg_desc,
> >  static void gve_dma_sync_for_device(struct device *dev, dma_addr_t *page_buses,
> >                                   u64 iov_offset, u64 iov_len)
> >  {
> > -     dma_addr_t dma;
> > -     u64 addr;
> > +     u64 last_page = (iov_offset + iov_len - 1) / PAGE_SIZE;
> > +     u64 first_page = iov_offset / PAGE_SIZE;
> > +     u64 page;
> >
> > -     for (addr = iov_offset; addr < iov_offset + iov_len;
> > -          addr += PAGE_SIZE) {
> > -             dma = page_buses[addr / PAGE_SIZE];
> > +     for (page = first_page; page <= last_page; page++) {
> > +             dma_addr_t dma = page_buses[page];
>
> Empty line after variable declaration. Perhaps keep the dma declaration
> outside the loop, since this is a fix the smaller the better.
>
> >               dma_sync_single_for_device(dev, dma, PAGE_SIZE, DMA_TO_DEVICE);
> >       }
> >  }
>

Comments Addressed in v2