[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.brezillon at collabora.com>
Reviewed-by: Steven Price <steven.price at arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau at 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