From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422747AbXCNXq6 (ORCPT ); Wed, 14 Mar 2007 19:46:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422750AbXCNXq5 (ORCPT ); Wed, 14 Mar 2007 19:46:57 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:42483 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422747AbXCNXq5 (ORCPT ); Wed, 14 Mar 2007 19:46:57 -0400 X-AuthUser: davidel@xmailserver.org Date: Wed, 14 Mar 2007 16:41:58 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Benjamin LaHaise cc: Linux Kernel Mailing List , Andrew Morton , Linus Torvalds , Ingo Molnar , Suparna Bhattacharya , Zach Brown Subject: Re: [patch 13/13] signalfd/timerfd/asyncfd v5 - KAIO asyncfd support (example/maybe-broken) ... In-Reply-To: <20070314234208.GC1246@kvack.org> Message-ID: References: <20070314231920.GB1246@kvack.org> <20070314234208.GC1246@kvack.org> X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 14 Mar 2007, Benjamin LaHaise wrote: > On Wed, Mar 14, 2007 at 04:24:54PM -0700, Davide Libenzi wrote: > > Can you point me to a kernel path that ends up calling aio_complete() in a > > do-not-sleep mode? > > If you remove that invariant, then it is very difficult for device drivers > and other code to make use of aio_complete(). > > > The offender I see is drivers/usb/gadget/inode.c that calls it with a > > spinlock held. > > Which was from irq context last time I checked. > > > The aio_run_iocb function seem to release/reacquire the lock before > > calling aio_complete(). > > That implies nothing -- aio_complete() has to acquire ctx_lock and cannot > be called holding the lock. Sure, it could probably be split into > __aio_complete() and have aio_complete() wrap it acquiring the lock. Yeah, of course. I do not plan revolutions. Just asking if it's a possible thing to do. I can mlock the userspace ring, if imposing that burden over aio_complete() is seen as too heavy. - Davide