linux-kernel - Re: [PATCH 2/2] auxdisplay/ht16k33.c: Convert to use vm_map_pages

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Message-ID: <CAFqt6zZA32QA-6VtaKcrEtq=qkoGLHpirSvXb5wt7-wd_-74hQ@mail.gmail.com>
Date:   Thu, 23 May 2019 13:48:26 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     Robin van der Gracht <robin@...tonic.nl>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH 2/2] auxdisplay/ht16k33.c: Convert to use vm_map_pages_zero()

On Tue, May 21, 2019 at 12:24 PM Robin van der Gracht <robin@...tonic.nl> wrote:
>
> On Mon, 20 May 2019 21:00:58 +0530
> Souptick Joarder <jrdr.linux@...il.com> wrote:
>
> > While using mmap, the incorrect value of length and vm_pgoff are
> > ignored and this driver go ahead with mapping fbdev.buffer
> > to user vma.
> >
> > Convert vm_insert_pages() to use vm_map_pages_zero(). We could later
> > "fix" these drivers to behave according to the normal vm_pgoff
> > offsetting simply by removing the _zero suffix on the function name
> > and if that causes regressions, it gives us an easy way to revert.
> >
> > Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> > ---
> >  drivers/auxdisplay/ht16k33.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
> > index 21393ec..9c0bb77 100644
> > --- a/drivers/auxdisplay/ht16k33.c
> > +++ b/drivers/auxdisplay/ht16k33.c
> > @@ -223,9 +223,9 @@ static int ht16k33_bl_check_fb(struct backlight_device *bl, struct fb_info *fi)
> >  static int ht16k33_mmap(struct fb_info *info, struct vm_area_struct *vma)
> >  {
> >       struct ht16k33_priv *priv = info->par;
> > +     struct page *pages = virt_to_page(priv->fbdev.buffer);
> >
> > -     return vm_insert_page(vma, vma->vm_start,
> > -                           virt_to_page(priv->fbdev.buffer));
> > +     return vm_map_pages_zero(vma, &pages, 1);
> >  }
> >
> >  static struct fb_ops ht16k33_fb_ops = {
>
> Acked-by: Robin van der Gracht <robin@...tonic.nl>

Miguel, Ack from Robin is missing in linux-next-20190523 when applied.