drm/etnaviv: add lockdep annotation for userptr object population

The current userptr page population will defer work to a work item if
needed to avoid ever taking the mmap_sem in the direct call path. With
the more fine-grained locking in etnaviv this isn't needed anymore, so
a future commit will simplify this code.

Add a lockdep annotation to validate the assumption that the mmap_sem
can be taken in the direct call path.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index e358250..555a331 100644 (file)
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -804,6 +804,8 @@ static int etnaviv_gem_userptr_get_pages(struct etnaviv_gem_object *etnaviv_obj)
        struct mm_struct *mm;
        int ret, pinned, npages = etnaviv_obj->base.size >> PAGE_SHIFT;
 
+       might_lock_read(&current->mm->mmap_sem);
+
        if (etnaviv_obj->userptr.work) {
                if (IS_ERR(etnaviv_obj->userptr.work)) {
                        ret = PTR_ERR(etnaviv_obj->userptr.work);