From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753764Ab0JZT1l (ORCPT ); Tue, 26 Oct 2010 15:27:41 -0400 Received: from smtp.nokia.com ([192.100.122.230]:40856 "EHLO mgw-mx03.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751786Ab0JZT1k (ORCPT ); Tue, 26 Oct 2010 15:27:40 -0400 From: Felipe Contreras Subject: RE: [PATCH 8/8] staging: tidspbridge - make sync_wait_on_event interruptible To: fernando.lugo@ti.com, felipe.contreras@gmail.com Cc: gregkh@suse.de, hiroshi.doyu@nokia.com, linux-kernel@vger.kernel.org, andy.shevchenko@gmail.com, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org In-Reply-To: <496565EC904933469F292DDA3F1663E602F49E28AB@dlee06.ent.ti.com> References: <1288054306-4361-1-git-send-email-x0095840@ti.com> <1288054306-4361-2-git-send-email-x0095840@ti.com> <1288054306-4361-3-git-send-email-x0095840@ti.com> <1288054306-4361-4-git-send-email-x0095840@ti.com> <1288054306-4361-5-git-send-email-x0095840@ti.com> <1288054306-4361-6-git-send-email-x0095840@ti.com> <1288054306-4361-7-git-send-email-x0095840@ti.com> <1288054306-4361-8-git-send-email-x0095840@ti.com> <1288054306-4361-9-git-send-email-x0095840@ti.com> <496565EC904933469F292DDA3F1663E602F49E2802@dlee06.ent.ti.com> <1288112260-notmuch-felipe.contreras@nokia.com> <496565EC904933469F292DDA3F1663E602F49E28AB@dlee06.ent.ti.com> User-Agent: notmuch 0.3.1-85-ge35d5aa Message-ID: <1288121052-notmuch-felipe.contreras@nokia.com> Date: Tue, 26 Oct 2010 22:27:23 +0300 X-OriginalArrivalTime: 26 Oct 2010 19:27:29.0755 (UTC) FILETIME=[D46FDAB0:01CB7543] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org fernando.lugo@ti.com wrote: > > fernando.lugo@ti.com wrote: > > > > On Tue, Oct 26, 2010 at 3:51 AM, Fernando Guzman Lugo > > > > wrote: > > > > > So that avoid non-killable process. > > > > > > > > It would be useful to interrupt these tasks from user-space. > > > > A separate ioctl to do that would be needed. > > > > > > I don't see use case where that could be needed. It is only > > To avoid a > > > nonkillable task in the case the user pass an infinite Timeout. > > > > > > If you have some test case where that ioctl would be needed Please > > > share it in order to find the best solution. > > > > Well, imagine the application is using a library to access > > the DSP, and the library has a dedicated thread listening for > > DSP events in a loop. > > This happens to be how libomxil-ti and gst-dsp work. > > > > Now, the thread received the last message, but has set a > > timeout of 10s, or even worst, no timeout at all. > > > > After realizing that was the last message, the main thread > > decides to shut down, but it has to wait for the DSP thread > > to join. Unfortunately the DSP thread is stuck waiting for > > events, and there's nothing that can be done. > > > > However, if we have a separate ioctl to interrupt that task, > > then the main thread can issue that ioctl, and unlock the DSP > > thread without having to wait 10s, or forever. > > > > Does that make sense? > > Maybe sending a signal to yourselft and having a dummy signal > Handle should work, it that would not like good. Signals on libraries is a no-no. > I am thinking On having a ioctl to create and set an event the you > could Something like this: > > struct dsp_notification events[3]; > > proc_register_notify(proc, event_type, &events[0]); > ... > proc_register_notify(proc, event_type, &events[1]); > ... > Sync_open_event(&events[2]); > > > second thread: > > mgr_wait_for_bridge_events(proc, events, 3, index); > > if (index == 2) > /* main thread force exit */ > > > Main thread: > > /* if some execption happened then finish the second thread */ > sync_set_event(events[2]); > > pthread_join(...); > > > However it is in progess a task for change replacing dspbridge sync.c > Module with event_fd to signal events to userspace. Where now simple > File descriptor will be used as event elements. So the mgr_wait_for_bridge_events > Will be implemented using "select" system call inside to wait for multiple events. > So you will be able to do something like this: > > int events[3]; > > proc_register_notify(proc, event_type, &events[0]); > ... > proc_register_notify(proc, event_type, &events[1]); > ... > events[2] = eventfd(0, 0); > > > second thread: > > mgr_wait_for_bridge_events(proc, events, 3, index); > > if (index == 2) > /* main thread force exit */ > > Main thread: > > /* if some execption happened then finish the second thread */ > write(events[2], "s", 1); > > pthread_join(...); > > You won't need any aditional ioctl in order to do what you want to do. > > So, I think it is not worth to make much changes to some module that will > Dissapear (my patch is just a fix it is not implementing something new), > It is just a matter of time to that task is finished and tested properly > And then send to LO. All right, that makes sense. I just wanted to make suere you are aware of that need. -- Felipe Contreras