[PATCH] drm/vboxvideo: Unmap iomem on probe-failure and remove

[Daniel Vetter]

On Thu, Nov 19, 2020 at 6:51 PM Dan Carpenter <dan.carpenter at oracle.com> wrote:
>
> On Thu, Nov 19, 2020 at 12:35:56PM +0100, Hans de Goede wrote:
> > Hi,
> >
> > On 10/27/20 2:51 PM, Hans de Goede wrote:
> > > Add missing pci_iounmap() calls to properly unmap the memory on
> > > probe-failure and remove.
> > >
> > > Reported-by: kernel test robot <lkp at intel.com>
> > > Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
> > > Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> >
> > For some reason the spam-filter used by Red Hat's email system has eaten
> > Daniel Vetter's reply to this, so let me copy and paste that from patchwork:
> >
> > Daniel Vetter wrote:
> >
> > > I think switching over to devm would be really nice. And for pci all
> > > you need to do is use pcim_enable_device and delete all the cleanup
> > > code, and it's all done. Hand rolling device cleanup code really isn't
> > > a great idea and way too error-prone. Plus you're using lots of devm_
> > > already.
> >
> > Good point, so I just checked and the vboxvideo code is already
> > using pcim_enable_device() so it looks like this is a false-positive
> > from the lkp at intel.com bot, and Dan Carpenter missed that pcim_enable_device()
> > makes all subsequent pci-resource acquiring calls behave like devm calls,
> > when he forwarded the report to me.
> >
> > Tl;DR: there is no bug / leak and this patch can be dropped.
> >
> > Is there a place where I can report a bug against the lkp at intel.com bot
> > for this false-positive ?
>
> Ah.  Thanks!
>
> This is a Smatch bug.  There is a list for that smatch at vger.kernel.org
> but I already remove the pci_iomap() from the list of functions that
> needs to be unwound based on your report.

I guess if smatch sees a pci_enable_device but not pcim_enable_device
on the same device as passed to pci_iomap (and a pile of other pci
functions) then it still must be unwound. Could smatch detect that?
There's a lot of pci drivers not using the managed functions, catching
bugs in these would be good.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch