From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964806AbXCNX36 (ORCPT ); Wed, 14 Mar 2007 19:29:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964813AbXCNX36 (ORCPT ); Wed, 14 Mar 2007 19:29:58 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:42470 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964806AbXCNX35 (ORCPT ); Wed, 14 Mar 2007 19:29:57 -0400 X-AuthUser: davidel@xmailserver.org Date: Wed, 14 Mar 2007 16:24:54 -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: <20070314231920.GB1246@kvack.org> Message-ID: References: <20070314231920.GB1246@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 03:19:21PM -0700, Davide Libenzi wrote: > > + /* > > + * Check if the user asked us to deliver the result through an > > + * asyncfd. Note that asyncfd_add_results() may sleep. It seems > > + * OK looking at the code, but I'm not sure since inside a USB driver, > > + * aio_complete() is called with a spinlock held. !!CHECK > > + */ > > That won't work. aio_complete() is supposed to be irq safe. Can you point me to a kernel path that ends up calling aio_complete() in a do-not-sleep mode? The offender I see is drivers/usb/gadget/inode.c that calls it with a spinlock held. The aio_run_iocb function seem to release/reacquire the lock before calling aio_complete(). - Davide