On Mon, Aug 17 2020 at 14:37, Qianli Zhao wrote: > From: Qianli Zhao <zhaoqia...@xiaomi.com> > > Add debugobject support to track the life time of kthread_work > which is used to detect reinitialization/free active object problems > Add kthread_init_work_onstack()/kthread_init_delayed_work_onstack() for > kthread onstack support > > If we reinitialize a kthread_work that has been activated, > this will cause delayed_work_list/work_list corruption. > enable this config,there is an chance to fixup these errors > or WARNING the wrong use of kthread_work > > [30858.395766] list_del corruption. next->prev should be ffffffe388ebbf88, > but was ffffffe388ebb588 > [30858.395788] WARNING: CPU: 2 PID: 387 at > kernel/msm-4.19/lib/list_debug.c:56 __list_del_entry_valid+0xc8/0xd0 > ... > [30858.395906] Call trace: > [30858.395909] __list_del_entry_valid+0xc8/0xd0 > [30858.395912] __kthread_cancel_work_sync+0x98/0x138 > [30858.395915] kthread_cancel_delayed_work_sync+0x10/0x20 > [30858.395917] sde_encoder_resource_control+0xe8/0x12c0 > [30858.395920] sde_encoder_prepare_for_kickoff+0x5dc/0x2008 > [30858.395923] sde_crtc_commit_kickoff+0x280/0x890 > [30858.395925] sde_kms_commit+0x16c/0x278 > [30858.395928] complete_commit+0x3c4/0x760 > [30858.395931] _msm_drm_commit_work_cb+0xec/0x1e0 > [30858.395933] kthread_worker_fn+0xf8/0x190 > [30858.395935] kthread+0x118/0x128 > [30858.395938] ret_from_fork+0x10/0x18 > > crash> struct kthread_worker.delayed_work_list 0xffffffe3893925f0 > [ffffffe389392620] delayed_work_list = { > next = 0xffffffe388ebbf88, > prev = 0xffffffe388ebb588 > } > crash> list 0xffffffe388ebbf88 > ffffffe388ebbf88
This changelog is confusing at best. Something like this perhaps? kthread_work is not covered by debug objects, but the same problems as with regular work objects apply. Some of the issues like reinitialization of an active kthread_work are hard to debug because the problem manifests itself later in a completely different context. Add debugobject support along with the necessary fixup functions to make debugging of these problems less tedious. > +static void stub_kthread_work(struct kthread_work *unuse) unused? > +{ > + WARN_ON(1); > +} > void kthread_flush_work(struct kthread_work *work) > { > struct kthread_flush_work fwork = { > - KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), > - COMPLETION_INITIALIZER_ONSTACK(fwork.done), > + .done = COMPLETION_INITIALIZER_ONSTACK(fwork.done), Eew. Why is the completion initialized seperately instead of being initialized as part of kthread_init_work_onstack() ? > }; > struct kthread_worker *worker; > bool noop = false; > > + debug_kwork_assert_init(work); > worker = work->worker; > if (!worker) > return; > > + kthread_init_work_onstack(&fwork.work, kthread_flush_work_fn); > > @@ -1194,12 +1319,13 @@ EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); > void kthread_flush_worker(struct kthread_worker *worker) > { > struct kthread_flush_work fwork = { > - KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), > - COMPLETION_INITIALIZER_ONSTACK(fwork.done), > + .done = COMPLETION_INITIALIZER_ONSTACK(fwork.done), > }; Ditto. > + kthread_init_work_onstack(&fwork.work, kthread_flush_work_fn); > kthread_queue_work(worker, &fwork.work); > wait_for_completion(&fwork.done); > + destroy_kwork_on_stack(&fwork.work); Thanks, tglx