linux-kernel - Re: [PATCH 5.12 237/242] drm/ast: Remove reference to struct drm

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Message-ID: <CAJn8CcHHKSo7GF29Z1ufXJJpMUzn6+fdvwiqe9=JvgpcfvnbHQ@mail.gmail.com>
Date:   Mon, 19 Jul 2021 19:43:39 +0800
From:   Xiaotian Feng <xtfeng@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        stable@...r.kernel.org, Thomas Zimmermann <tzimmermann@...e.de>,
        "Michael J. Ruhl" <michael.j.ruhl@...el.com>,
        KuoHsiang Chou <kuohsiang_chou@...eedtech.com>,
        kernel test robot <lkp@...el.com>,
        Dave Airlie <airlied@...hat.com>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 5.12 237/242] drm/ast: Remove reference to struct drm_device.pdev

On Mon, Jul 19, 2021 at 7:23 PM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Mon, Jul 19, 2021 at 05:57:30PM +0800, Xiaotian Feng wrote:
> > On Fri, Jul 16, 2021 at 5:13 AM Greg Kroah-Hartman
> > <gregkh@...uxfoundation.org> wrote:
> > >
> > > From: Thomas Zimmermann <tzimmermann@...e.de>
> > >
> > > commit 0ecb51824e838372e01330752503ddf9c0430ef7 upstream.
> > >
> > > Using struct drm_device.pdev is deprecated. Upcast with to_pci_dev()
> > > from struct drm_device.dev to get the PCI device structure.
> > >
> > > v9:
> > >         * fix remaining pdev references
> > >
> > > Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
> > > Reviewed-by: Michael J. Ruhl <michael.j.ruhl@...el.com>
> > > Fixes: ba4e0339a6a3 ("drm/ast: Fixed CVE for DP501")
> > > Cc: KuoHsiang Chou <kuohsiang_chou@...eedtech.com>
> > > Cc: kernel test robot <lkp@...el.com>
> > > Cc: Thomas Zimmermann <tzimmermann@...e.de>
> > > Cc: Dave Airlie <airlied@...hat.com>
> > > Cc: dri-devel@...ts.freedesktop.org
> > > Link: https://patchwork.freedesktop.org/patch/msgid/20210429105101.25667-2-tzimmermann@suse.de
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > > ---
> > >  drivers/gpu/drm/ast/ast_main.c |    5 ++---
> > >  1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > --- a/drivers/gpu/drm/ast/ast_main.c
> > > +++ b/drivers/gpu/drm/ast/ast_main.c
> > > @@ -411,7 +411,6 @@ struct ast_private *ast_device_create(co
> > >                 return ast;
> > >         dev = &ast->base;
> > >
> > > -       dev->pdev = pdev;
> > >         pci_set_drvdata(pdev, dev);
> > >
> > >         ast->regs = pcim_iomap(pdev, 1, 0);
> > > @@ -453,8 +452,8 @@ struct ast_private *ast_device_create(co
> > >
> > >         /* map reserved buffer */
> > >         ast->dp501_fw_buf = NULL;
> > > -       if (dev->vram_mm->vram_size < pci_resource_len(dev->pdev, 0)) {
> > > -               ast->dp501_fw_buf = pci_iomap_range(dev->pdev, 0, dev->vram_mm->vram_size, 0);
> > > +       if (dev->vram_mm->vram_size < pci_resource_len(pdev, 0)) {
> > > +               ast->dp501_fw_buf = pci_iomap_range(pdev, 0, dev->vram_mm->vram_size, 0);
> > >                 if (!ast->dp501_fw_buf)
> > >                         drm_info(dev, "failed to map reserved buffer!\n");
> > >         }
> > >
> >
> > Hi Greg,
> >
> >      This backport is incomplete for 5.10 kernel,  kernel is panicked
> > on RIP: ast_device_create+0x7d.  When I look into the crash code, I
> > found
> >
> > struct ast_private *ast_device_create(struct drm_driver *drv,
> >                                       struct pci_dev *pdev,
> >                                       unsigned long flags)
> > {
> > .......
> >         dev->pdev = pdev;  // This is removed
> >         pci_set_drvdata(pdev, dev);
> >
> >         ast->regs = pcim_iomap(pdev, 1, 0);
> >         if (!ast->regs)
> >                 return ERR_PTR(-EIO);
> >
> >         /*
> >          * If we don't have IO space at all, use MMIO now and
> >          * assume the chip has MMIO enabled by default (rev 0x20
> >          * and higher).
> >          */
> >         if (!(pci_resource_flags(dev->pdev, 2) & IORESOURCE_IO)) { //
> > dev->pdev is in used here.
> >                 drm_info(dev, "platform has no IO space, trying MMIO\n");
> >                 ast->ioregs = ast->regs + AST_IO_MM_OFFSET;
> >         }
> >
> >         That's because commit 46fb883c3d0d8a823ef995ddb1f9b0817dea6882
> > is not backported to 5.10 kernel.
>
> So what should I do here?  Backport that commit (was was not called
> out), or just revert this?
>
I think we can just simply revert the patch. Because commit 46fb883c
removed drm_device.pdev usage,
then commit ba4e0339 used drm_device.pdev again. Since commit 46fb883c
is not in 5.10.50 kernel,
it's not a stable fix.

> thanks,
>
> greg k-h