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SubjectRe: [PATCH] drm/cma: Fix recent regression of mmap() in the MMU case.
On Mon, Apr 17, 2017 at 04:31:24PM -0700, Eric Anholt wrote:
> The stub get_unmapped_area() function was actually getting called, so
> all of our mmap()s failed.
>
> Cc: Yannick Fertre <yannick.fertre@st.com>
> Fixes: 97bf3a9aa60f ("drm/cma: Update DEFINE_DRM_GEM_CMA_FOPS to add get_unmapped_area")
> Signed-off-by: Eric Anholt <eric@anholt.net>

Oh drat, I assumed the core would only call this when needed, but things
don't work like that.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

The strange thing is that in some cases ->mm->get_unmapped_area overwrites
fops->get_unmapped_area, but not for do_mmap in the mmu case. Seems not
entirely thought out to me ...
-Daniel

> ---
> include/drm/drm_gem_cma_helper.h | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
> index 7320b140545a..b42529e0fae0 100644
> --- a/include/drm/drm_gem_cma_helper.h
> +++ b/include/drm/drm_gem_cma_helper.h
> @@ -26,6 +26,13 @@ to_drm_gem_cma_obj(struct drm_gem_object *gem_obj)
> return container_of(gem_obj, struct drm_gem_cma_object, base);
> }
>
> +#ifndef CONFIG_MMU
> +#define DRM_GEM_CMA_UNMAPPED_AREA_FOPS \
> + .get_unmapped_area = drm_gem_cma_get_unmapped_area,
> +#else
> +#define DRM_GEM_CMA_UNMAPPED_AREA_FOPS
> +#endif
> +
> /**
> * DEFINE_DRM_GEM_CMA_FOPS() - macro to generate file operations for CMA drivers
> * @name: name for the generated structure
> @@ -50,7 +57,7 @@ to_drm_gem_cma_obj(struct drm_gem_object *gem_obj)
> .read = drm_read,\
> .llseek = noop_llseek,\
> .mmap = drm_gem_cma_mmap,\
> - .get_unmapped_area = drm_gem_cma_get_unmapped_area,\
> + DRM_GEM_CMA_UNMAPPED_AREA_FOPS \
> }
>
> /* free GEM object */
> @@ -86,15 +93,6 @@ unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
> unsigned long len,
> unsigned long pgoff,
> unsigned long flags);
> -#else
> -static inline unsigned long drm_gem_cma_get_unmapped_area(struct file *filp,
> - unsigned long addr,
> - unsigned long len,
> - unsigned long pgoff,
> - unsigned long flags)
> -{
> - return -EINVAL;
> -}
> #endif
>
> #ifdef CONFIG_DEBUG_FS
> --
> 2.11.0
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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