[PATCH] vboxvideo: Fix incorrect type in assignment sparse warning - dri-devel - freedesktop.org experimental mailing list

6 Jan 2018

On Sat, Jan 6, 2018 at 6:00 PM, Hans de Goede hdegoede@redhat.com wrote:
...
Hi,
On 06-01-18 15:20, Alexander Kapshuk wrote:
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On Mon, Dec 25, 2017 at 04:42:59PM +0200, Alexander Kapshuk wrote:
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Sparse emitted the following warning:
../drivers/staging/vboxvideo/vbox_fb.c:173:27: warning: incorrect type in
assignment (different address spaces)
../drivers/staging/vboxvideo/vbox_fb.c:173:27:    expected char [noderef]
asn:2*screen_base
../drivers/staging/vboxvideo/vbox_fb.c:173:27:    got void *virtual
The vbox_bo buffer object kernel mapping is handled by a call
to ttm_bo_kmap() prior to the assignment of bo->kmap.virtual to
info->screen_base of type char __iomem*.
Casting bo->kmap.virtual to char __iomem* in this assignment fixes
the warning.
vboxvideo: Fix address space of expression removal sparse warning
Sparse emitted the following warning:
../drivers/staging/vboxvideo/vbox_main.c:64:25: warning: cast removes
address space of expression
vbox->vbva_buffers iomapping is handled by calling vbox_accel_init()
from vbox_hw_init().
__force attribute is used in assignment to vbva to fix the warning.
Signed-off-by: Alexander Kapshuk alexander.kapshuk@gmail.com
drivers/staging/vboxvideo/vbox_fb.c   | 2 +-
  drivers/staging/vboxvideo/vbox_main.c | 2 +-
  2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/vboxvideo/vbox_fb.c
b/drivers/staging/vboxvideo/vbox_fb.c
index 8aed248db6e2..43c39eca4ae1 100644
--- a/drivers/staging/vboxvideo/vbox_fb.c
+++ b/drivers/staging/vboxvideo/vbox_fb.c
@@ -170,7 +170,7 @@ static int vboxfb_create(struct drm_fb_helper
*helper,
        drm_fb_helper_fill_var(info, &fbdev->helper, sizes->fb_width,
                               sizes->fb_height);

  info->screen_base = bo->kmap.virtual;




  info->screen_base = (char __iomem *)bo->kmap.virtual;
  info->screen_size = size;


#ifdef CONFIG_DRM_KMS_FB_HELPER


This fix looks good to me.
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diff --git a/drivers/staging/vboxvideo/vbox_main.c
b/drivers/staging/vboxvideo/vbox_main.c
index 80bd039fa08e..973b3bcc04b1 100644
--- a/drivers/staging/vboxvideo/vbox_main.c
+++ b/drivers/staging/vboxvideo/vbox_main.c
@@ -61,7 +61,7 @@ void vbox_enable_accel(struct vbox_private *vbox)
                if (vbox->vbva_info[i].vbva)
                        continue;

          vbva = (void *)vbox->vbva_buffers + i *



VBVA_MIN_BUFFER_SIZE;

          vbva = (void __force *)vbox->vbva_buffers + i *



VBVA_MIN_BUFFER_SIZE;
                if (!vbva_enable(&vbox->vbva_info[i],
                                 vbox->guest_pool, vbva, i)) {
                        /* very old host or driver error. */
Hmm, isn't there a cleaner way to fix this ? Maybe make vbva_enable's
argument (and the local vbva variable) of type u8 __iomem * too ?
Regards,
Hans
Hi Hans,
Thanks for your prompt response.
I had a good look at the vbva_enable() function's definition and to
the best of my knowledge, changing vbva's type from 'struct
vbva_buffer *' to 'u8 __iomem *' wouldn't work.
vbva_enable() relies on vbva's type being a pointer to 'struct vbva_buffer':
vbva's memory gets set to zero;
some of vbva's members are initialised to particular values;
vbva_ctx->vbva expects vbva to be a pointer to 'struct vbva_buffer' as well;
Or am I misreading this?
What are your thoughts on this?
Thanks.
Alexander.

    