Hi On Tue, Jan 21, 2014 at 10:41 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Mon, Jan 20, 2014 at 08:26:25PM +0100, David Herrmann wrote: >> Instead of rounding down to the next lower page-boundary, round up. >> dma-buf guarantees that we can map buffers in multiples of a page, so if >> an exporter does not page-align, do it ourselves. >> >> This avoids issues if the exported buffer contains an unaligned size and >> we crop it. In this case, the buffer is too small for the UDL CRTC. So we >> round up to page-size now and avoid black borders. Worst case is we end up >> reading out some random kernel memory, but we can never fault as the whole >> page has the same access-rights. And in this case it's an issue of the >> buggy exporting driver, not the importing one. >> >> Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx> >> --- >> drivers/gpu/drm/udl/udl_gem.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c >> index df963a1..1069e57 100644 >> --- a/drivers/gpu/drm/udl/udl_gem.c >> +++ b/drivers/gpu/drm/udl/udl_gem.c >> @@ -227,7 +227,7 @@ static int udl_prime_create(struct drm_device *dev, >> struct udl_gem_object *obj; >> int npages; >> >> - npages = size / PAGE_SIZE; >> + npages = PAGE_ALIGN(size) >> PAGE_SHIFT; > > Imo the proper patch would be to reject exporting anything which isn't > page-aligned as a dma-buf in the driver core (together with a quick review > of the docs to make sure this requirement is clear). This is just a bug in > the exporter. Ok, I've dropped this one for now. I think the best way to deal with it is to make dma_buf disallow any non-aligned sizes during initialization. So we should just assume it's always page-aligned. Thanks David _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
