[PATCH v3] drm/panthor: Don't create a file offset for NO_MMAP BOs

[Boris Brezillon]

Right now the DRM_PANTHOR_BO_NO_MMAP flag is ignored by
panthor_ioctl_bo_mmap_offset(), meaning BOs with this flag set can
have a file offset but can't be mapped anyway, because
panthor_gem_mmap() will filter them out.

If we error out at mmap_offset creation time, we can get rid of
panthor_gem_mmap() and call drm_gem_shmem_object_mmap directly, and
we get rid of this inconsistency of having an mmap offset for a
BO that can never be mmap-ed.

Changes in v2:
- Get rid of panthor_gem_mmap()
- Get rid of the Fixes tag and adjust the commit message accordingly
- Return ENOPERM instead of EINVAL

Changes in v3:
- Don't leak the BO ref
- Add R-bs

Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com>
Reviewed-by: Steven Price <steven.pr...@arm.com>
Reviewed-by: Liviu Dudau <liviu.du...@arm.com>
---
 drivers/gpu/drm/panthor/panthor_drv.c |  7 +++++++
 drivers/gpu/drm/panthor/panthor_gem.c | 13 +------------
 2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_drv.c 
b/drivers/gpu/drm/panthor/panthor_drv.c
index 06fe46e32073..4d4a52a033f6 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -940,6 +940,7 @@ static int panthor_ioctl_bo_mmap_offset(struct drm_device 
*ddev, void *data,
                                        struct drm_file *file)
 {
        struct drm_panthor_bo_mmap_offset *args = data;
+       struct panthor_gem_object *bo;
        struct drm_gem_object *obj;
        int ret;
 
@@ -950,6 +951,12 @@ static int panthor_ioctl_bo_mmap_offset(struct drm_device 
*ddev, void *data,
        if (!obj)
                return -ENOENT;
 
+       bo = to_panthor_bo(obj);
+       if (bo->flags & DRM_PANTHOR_BO_NO_MMAP) {
+               ret = -EPERM;
+               goto out;
+       }
+
        ret = drm_gem_create_mmap_offset(obj);
        if (ret)
                goto out;
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c 
b/drivers/gpu/drm/panthor/panthor_gem.c
index fd014ccc3bfc..22d78cef9c66 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -129,17 +129,6 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, 
struct panthor_vm *vm,
        return ERR_PTR(ret);
 }
 
-static int panthor_gem_mmap(struct drm_gem_object *obj, struct vm_area_struct 
*vma)
-{
-       struct panthor_gem_object *bo = to_panthor_bo(obj);
-
-       /* Don't allow mmap on objects that have the NO_MMAP flag set. */
-       if (bo->flags & DRM_PANTHOR_BO_NO_MMAP)
-               return -EINVAL;
-
-       return drm_gem_shmem_object_mmap(obj, vma);
-}
-
 static struct dma_buf *
 panthor_gem_prime_export(struct drm_gem_object *obj, int flags)
 {
@@ -169,7 +158,7 @@ static const struct drm_gem_object_funcs panthor_gem_funcs 
= {
        .get_sg_table = drm_gem_shmem_object_get_sg_table,
        .vmap = drm_gem_shmem_object_vmap,
        .vunmap = drm_gem_shmem_object_vunmap,
-       .mmap = panthor_gem_mmap,
+       .mmap = drm_gem_shmem_object_mmap,
        .status = panthor_gem_status,
        .export = panthor_gem_prime_export,
        .vm_ops = &drm_gem_shmem_vm_ops,
-- 
2.49.0