Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932995AbXBYUcT (ORCPT ); Sun, 25 Feb 2007 15:32:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933700AbXBYUcT (ORCPT ); Sun, 25 Feb 2007 15:32:19 -0500 Received: from mail.screens.ru ([213.234.233.54]:53285 "EHLO mail.screens.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932995AbXBYUcS (ORCPT ); Sun, 25 Feb 2007 15:32:18 -0500 Date: Sun, 25 Feb 2007 23:31:54 +0300 From: Oleg Nesterov To: "Rafael J. Wysocki" Cc: Aneesh Kumar , Pavel Machek , LKML , paulmck@linux.vnet.ibm.com, ego@in.ibm.com, akpm@osdl.org, mingo@elte.hu, vatsa@in.ibm.com, dipankar@in.ibm.com, venkatesh.pallipadi@intel.com Subject: Re: [RFC][PATCH 4/7] Freezer: Fix vfork problem Message-ID: <20070225203154.GA2276@tv-sign.ru> References: <200702231116.23607.rjw@sisk.pl> <200702252017.22077.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200702252017.22077.rjw@sisk.pl> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2170 Lines: 62 On 02/25, Rafael J. Wysocki wrote: > > On Sunday, 25 February 2007 16:40, Aneesh Kumar wrote: > > On 2/25/07, Aneesh Kumar wrote: > > > On 2/25/07, Rafael J. Wysocki wrote: > > > > On Sunday, 25 February 2007 15:33, Aneesh Kumar wrote: > > > > > On 2/25/07, Rafael J. Wysocki wrote: > [--snip--] > > > > Thinking about this i guess we have a problem with the above approach > > i outlined. if we have one task that is waiting on the event and more > > than one that can generate the event then the above logic would not > > work. Also with cases other than vfork; logic of tracking the waiting > > task gets complex. I guess what we have right now is better. > > I assume by "righ now" you mean the latest version of my patch. ;-) > > Still, having pondered the Pavel's suggestion for a while I think it's doable > without the addtitional process flag. Patch below. Probably I missed something, (I didn't see this patch and I missed the start of discussion), but I can't understand this patch. > +__wait_for_completion(struct completion *x, int freezable) > { > might_sleep(); > > @@ -3817,6 +3818,9 @@ void fastcall __sched wait_for_completio > __set_current_state(TASK_UNINTERRUPTIBLE); > spin_unlock_irq(&x->wait.lock); > schedule(); > + if (freezable) > + try_to_freeze(); > + > spin_lock_irq(&x->wait.lock); > } while (!x->done); > __remove_wait_queue(&x->wait, &wait); > @@ -3824,7 +3828,7 @@ void fastcall __sched wait_for_completio > x->done--; > spin_unlock_irq(&x->wait.lock); > } > > .......... > > @@ -48,6 +48,9 @@ void refrigerator(void) > task_unlock(current); > return; > } > + if (current->vfork_done) > + wake_up_process(current->parent); > + What if current->parent doesn't have TIF_FREEZE yet? ->parent will schedule() again, child goes to refrigerator. Now, how can we freeze the ->parent? Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/