On Mon, Jun 08, 2020 at 04:40:26PM +0200, Thomas Zimmermann wrote:
> Hi
>
> Am 03.06.20 um 15:12 schrieb Daniel Vetter:
> > On Thu, May 14, 2020 at 09:30:04AM +0200, Thomas Zimmermann wrote:
> >> Hi
> >>
> >> Am 11.05.20 um 11:35 schrieb Daniel Vetter:
> >>> Just a bit of light paranoia. Also sprinkle this check over
> >>> drm_gem_shmem_get_sg_table, which should only be called when
> >>> exporting, same for the pin/unpin functions, on which it relies to
> >>> work correctly.
> >>>
> >>> Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> >>> Cc: Rob Herring <robh@xxxxxxxxxx>
> >>> Cc: Noralf Trønnes <noralf@xxxxxxxxxxx>
> >>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> >>> ---
> >>> drivers/gpu/drm/drm_gem_shmem_helper.c | 10 ++++++++++
> >>> 1 file changed, 10 insertions(+)
> >>>
> >>> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> >>> index 117a7841e284..f7011338813e 100644
> >>> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> >>> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> >>> @@ -170,6 +170,8 @@ int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> >>> {
> >>> int ret;
> >>>
> >>> + WARN_ON(shmem->base.import_attach);
> >>> +
> >>> ret = mutex_lock_interruptible(&shmem->pages_lock);
> >>> if (ret)
> >>> return ret;
> >>> @@ -225,6 +227,8 @@ int drm_gem_shmem_pin(struct drm_gem_object *obj)
> >>> {
> >>> struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> >>>
> >>> + WARN_ON(shmem->base.import_attach);
> >>> +
> >>
> >> I don't understand this change. If a driver pins pages it now has to
> >> check that the pages are not imported?
> >
> > Nope. There's two classes of functions in the helpers, and I'm trying to
> > unconfuse them:
> >
> > - stuff used to implement gem_funcs. These are obviously only ever used on
> > native objects, never on imported ones (on imported ones we try to
> > forward through the dma-buf layer to the exporter). drm_gem_shmem_pin is
> > only used in that role to implement gem_funcs->pin. Calling it on an
> > imported buffer is indeed a bug.
> >
> > - the other set of functions are for drivers to do their stuff. The
> > interface which (implicitly) pins stuff into places is various set of
> > get_pages, which do have different paths for native and imported
> > objects.
>
> Thanks for explaining. Patch is
Thanks for taking a look at all this, last 2 patches now also merged to
drm-misc-next.
-Daniel
>
> Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>
> >
> > Apologies that I missed your question here, I merged all the patches
> > leading up to this one for now.
> >
> > Thanks, Daniel
> >
> >>
> >>
> >>> return drm_gem_shmem_get_pages(shmem);
> >>> }
> >>> EXPORT_SYMBOL(drm_gem_shmem_pin);
> >>> @@ -240,6 +244,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
> >>> {
> >>> struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> >>>
> >>> + WARN_ON(shmem->base.import_attach);
> >>> +
> >>> drm_gem_shmem_put_pages(shmem);
> >>> }
> >>> EXPORT_SYMBOL(drm_gem_shmem_unpin);
> >>> @@ -510,6 +516,8 @@ static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
> >>> struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> >>> int ret;
> >>>
> >>> + WARN_ON(shmem->base.import_attach);
> >>> +
> >>> ret = drm_gem_shmem_get_pages(shmem);
> >>> WARN_ON_ONCE(ret != 0);
> >>>
> >>> @@ -611,6 +619,8 @@ struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
> >>> {
> >>> struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> >>>
> >>> + WARN_ON(shmem->base.import_attach);
> >>> +
> >>> return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
> >>> }
> >>> EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
> >>>
> >>
> >> --
> >> Thomas Zimmermann
> >> Graphics Driver Developer
> >> SUSE Software Solutions Germany GmbH
> >> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >> (HRB 36809, AG Nürnberg)
> >> Geschäftsführer: Felix Imendörffer
> >>
> >
> >
> >
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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