On 04/24/2018 03:44 PM, Daniel Vetter wrote: > On Tue, Apr 24, 2018 at 05:46:52PM +0200, Michel Dänzer wrote: >> Adding the dri-devel list, since this is driver independent code. >> >> >> On 2018-04-24 05:30 PM, Andrey Grodzovsky wrote: >>> Avoid calling wait_event_killable when you are possibly being called >>> from get_signal routine since in that case you end up in a deadlock >>> where you are alreay blocked in singla processing any trying to wait >> Multiple typos here, "[...] already blocked in signal processing and [...]"? >> >> >>> on a new signal. >>> >>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky at amd.com> >>> --- >>> drivers/gpu/drm/scheduler/gpu_scheduler.c | 5 +++-- >>> 1 file changed, 3 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c >>> index 088ff2b..09fd258 100644 >>> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c >>> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c >>> @@ -227,9 +227,10 @@ void drm_sched_entity_do_release(struct drm_gpu_scheduler *sched, >>> return; >>> /** >>> * The client will not queue more IBs during this fini, consume existing >>> - * queued IBs or discard them on SIGKILL >>> + * queued IBs or discard them when in death signal state since >>> + * wait_event_killable can't receive signals in that state. >>> */ >>> - if ((current->flags & PF_SIGNALED) && current->exit_code == SIGKILL) >>> + if (current->flags & PF_SIGNALED) > You want fatal_signal_pending() here, instead of inventing your own broken > version. I rely on current->flags & PF_SIGNALED because this being set from within get_signal, meaning I am within signal processing in which case I want to avoid any signal based wait for that task, From what i see in the code, task_struct.pending.signal is being set for other threads in same group (zap_other_threads) or for other scenarios, those task are still able to receive signals so calling wait_event_killable there will not have problem. >>> entity->fini_status = -ERESTARTSYS; >>> else >>> entity->fini_status = wait_event_killable(sched->job_scheduled, > But really this smells like a bug in wait_event_killable, since > wait_event_interruptible does not suffer from the same bug. It will return > immediately when there's a signal pending. Even when wait_event_interruptible is called as following - ...->do_signal->get_signal->....->wait_event_interruptible ? I haven't tried it but wait_event_interruptible is very much alike to wait_event_killable so I would assume it will also not be interrupted if called like that. (Will give it a try just out of curiosity anyway) Andrey > > I think this should be fixed in core code, not papered over in some > subsystem. > -Daniel > >> >> -- >> Earthling Michel Dänzer | http://www.amd.com >> Libre software enthusiast | Mesa and X developer >> _______________________________________________ >> dri-devel mailing list >> dri-devel at lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
