Hi,
Just a comment about the comments:
On 1/18/21 10:03 AM, Christian König wrote:
DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT can't be used when we hold locks since we are basically waiting for userspace to do something.
Holding a lock while doing so can trivial deadlock with page faults etc...
So make lockdep complain when a driver tries to do this.
v2: Add lockdep_assert_none_held() macro.
Signed-off-by: Christian König christian.koenig@amd.com
drivers/gpu/drm/drm_syncobj.c | 7 +++++++ include/linux/lockdep.h | 5 +++++ 2 files changed, 12 insertions(+)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index 6e74e6745eca..f51458615158 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -387,6 +387,13 @@ int drm_syncobj_find_fence(struct drm_file *file_private, if (!syncobj) return -ENOENT;
- /* Waiting for userspace with locks help is illegal cause that can
held because
* trivial deadlock with page faults for example. Make lockdep complain
trivially
* about it early on.*/- if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT)
lockdep_assert_none_held_once();- *fence = drm_syncobj_fence_get(syncobj); drm_syncobj_put(syncobj);
thanks.