[10/15] drm/vmwgfx: Delete mmaping functions
diff mbox series

Message ID 20191118103536.17675-11-daniel.vetter@ffwll.ch
State New
Headers show
Series
  • Retire dma_buf_k(un)map
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Commit Message

Daniel Vetter Nov. 18, 2019, 10:35 a.m. UTC
No need for stubs, dma-buf.c takes care of that.

Aside, not having a ->release callback smelled like refcounting leak
somewhere. It will also score you a WARN_ON backtrace in dma-buf.c on
every export. But then I found that ttm_device_object_init overwrites
it. Overwriting const memory is not going to go down well in recent
kernels.

One more aside: The (un)map_dma_buf can't ever be called because
->attach rejects everything. Might want to drop a BUG_ON(1) in there.
Same for ->detach.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_prime.c | 33 ---------------------------
 1 file changed, 33 deletions(-)

Comments

Thomas Hellstrom Nov. 18, 2019, 5:25 p.m. UTC | #1
On Mon, 2019-11-18 at 11:35 +0100, Daniel Vetter wrote:
> No need for stubs, dma-buf.c takes care of that.
> 
> Aside, not having a ->release callback smelled like refcounting leak
> somewhere. It will also score you a WARN_ON backtrace in dma-buf.c on
> every export. But then I found that ttm_device_object_init overwrites
> it. Overwriting const memory is not going to go down well in recent
> kernels.

It's actually taking a non-const copy and updating it. Not that that's
much better, but at least it won't crash due to writing to wp memory.
I'll add a backlog item to revisit this.

> 
> One more aside: The (un)map_dma_buf can't ever be called because
> ->attach rejects everything. Might want to drop a BUG_ON(1) in there.
> Same for ->detach.

And this.

> 
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
> Cc: Thomas Hellstrom <thellstrom@vmware.com>
> ---
> 


Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

Will you be taking this through drm-misc?

Thanks,
Thomas
Daniel Vetter Nov. 18, 2019, 5:42 p.m. UTC | #2
On Mon, Nov 18, 2019 at 6:25 PM Thomas Hellstrom <thellstrom@vmware.com> wrote:
>
> On Mon, 2019-11-18 at 11:35 +0100, Daniel Vetter wrote:
> > No need for stubs, dma-buf.c takes care of that.
> >
> > Aside, not having a ->release callback smelled like refcounting leak
> > somewhere. It will also score you a WARN_ON backtrace in dma-buf.c on
> > every export. But then I found that ttm_device_object_init overwrites
> > it. Overwriting const memory is not going to go down well in recent
> > kernels.
>
> It's actually taking a non-const copy and updating it. Not that that's
> much better, but at least it won't crash due to writing to wp memory.
> I'll add a backlog item to revisit this.

Hm I was looking for that, but didn't spot where it does that. I'll
update the commit message when merging.

> > One more aside: The (un)map_dma_buf can't ever be called because
> > ->attach rejects everything. Might want to drop a BUG_ON(1) in there.
> > Same for ->detach.
>
> And this.
>
> >
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
> > Cc: Thomas Hellstrom <thellstrom@vmware.com>
> > ---
> >
>
>
> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

Thanks for your review.

> Will you be taking this through drm-misc?

Yup, that's the plan.
-Daniel

Patch
diff mbox series

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c b/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c
index e420675e8db3..d9552a1efd13 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c
@@ -62,45 +62,12 @@  static void vmw_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
 {
 }
 
-static void *vmw_prime_dmabuf_vmap(struct dma_buf *dma_buf)
-{
-	return NULL;
-}
-
-static void vmw_prime_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
-{
-}
-
-static void *vmw_prime_dmabuf_kmap(struct dma_buf *dma_buf,
-		unsigned long page_num)
-{
-	return NULL;
-}
-
-static void vmw_prime_dmabuf_kunmap(struct dma_buf *dma_buf,
-		unsigned long page_num, void *addr)
-{
-
-}
-
-static int vmw_prime_dmabuf_mmap(struct dma_buf *dma_buf,
-				 struct vm_area_struct *vma)
-{
-	WARN_ONCE(true, "Attempted use of dmabuf mmap. Bad.\n");
-	return -ENOSYS;
-}
-
 const struct dma_buf_ops vmw_prime_dmabuf_ops =  {
 	.attach = vmw_prime_map_attach,
 	.detach = vmw_prime_map_detach,
 	.map_dma_buf = vmw_prime_map_dma_buf,
 	.unmap_dma_buf = vmw_prime_unmap_dma_buf,
 	.release = NULL,
-	.map = vmw_prime_dmabuf_kmap,
-	.unmap = vmw_prime_dmabuf_kunmap,
-	.mmap = vmw_prime_dmabuf_mmap,
-	.vmap = vmw_prime_dmabuf_vmap,
-	.vunmap = vmw_prime_dmabuf_vunmap,
 };
 
 int vmw_prime_fd_to_handle(struct drm_device *dev,