Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760226AbXEQENQ (ORCPT ); Thu, 17 May 2007 00:13:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755103AbXEQENE (ORCPT ); Thu, 17 May 2007 00:13:04 -0400 Received: from ik-out-1112.google.com ([66.249.90.181]:60659 "EHLO ik-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754870AbXEQENB (ORCPT ); Thu, 17 May 2007 00:13:01 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=CUweSuISMcxXfZGtIz4VoLkqXG6/fkJnBcIyvLPS9G0/j7sZlsAXPhsOZVCqQLjpOLKtSrOs6PhUrahaH/jr2VIjbu0X+erWUowTffoskyuValZtXuYd8kTqOPUJgaMscXO/6MWL23GGmzjh7GmzJGQPvI/rvfmsBbNzWZgOZ+E= Message-ID: Date: Thu, 17 May 2007 09:43:00 +0530 From: "Satyam Sharma" To: "Ray Lee" Subject: Re: [PATCH] make hci_notifier a blocking notifier (was Re: BUG: sleeping function called from invalid context at net/core/sock.c:1523) Cc: "Alan Stern" , LKML , "Max Krasnyansky" , marcel@holtmann.org, bluez-devel@lists.sourceforge.net In-Reply-To: <2c0942db0705161209u5a0f1b8ay6864f9b9c4f7aac1@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <2c0942db0705061615i1c6147a1h6aca54012c3509aa@mail.gmail.com> <2c0942db0705161209u5a0f1b8ay6864f9b9c4f7aac1@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3568 Lines: 75 On 5/17/07, Ray Lee wrote: > Apologies for taking so long to get back to you -- I've been on the > road for the last week and have finally got to a point where I could > test the patch. > > On 5/6/07, Satyam Sharma wrote: > > (Dropped Pavel, Rafael and linux-pm from CC list, this isn't a PM > > error so don't want to spam them; and added bluez-devel) > > > > On 5/7/07, Ray Lee wrote: > > > On 5/6/07, Alan Stern wrote: > > > > On Sun, 6 May 2007, Satyam Sharma wrote: > > > > > > > > > Anyway, the hci_notifier is called from the following six call sites: > > > > > > > > > > hci_dev_open() and hci_dev_close() -> both called from > > > > > hci_sock_ioctl() => both can sleep > > > > > hci_register_dev() and hci_unregister_dev() => again both are capable > > > > > of sleeping > > > > > hci_suspend_dev() and hci_resume_dev() -> called from the .suspend() > > > > > and .resume() of the hci_usb_driver, and again both of these can sleep > > > > > > > > > > Is there any other reason why hci_notifier must be an atomic notifier? > > > > > > > > > > (CC'ing Alan Stern just in case, apparently hci_notifier became atomic > > > > > when notifier chains were classified into atomic / blocking) > > > > > > > > I don't remember exactly why this particular choice was made. Perhaps we > > > > found that the notifier callout routines didn't use any blocking > > > > primitives (we may have been mistaken about this -- there was a lot of > > > > code to check) and so therefore the choice didn't matter. In that case we > > > > probably just decided to make it an atomic notifier to keep things simple. > > > > > > > > As you found, changing it to a blocking notifier is very easy. Provided > > > > all the callers are non-atomic it should work just fine. > > > > > > Okay, I'll go ahead and try the patch, then, and report back. > > > > You'd still get the BUG message. To fully resolve the problem, we need > > to make the hci_sock_dev_event() notifier callout blocking (which > > happened with this patch) but also convert hci_sk_list.lock to a > > rwsem, but some users of that rwlock (other than hci_sock_dev_event) > > are atomic. > > > > However, please do try and get back, as your testing would still be > > helpful to see whether converting hci_notifier to blocking had other > > side-effects -- if you only see the same message again and otherwise > > things seem fine, then we're good as far as at least this change was > > concerned. > > Yes, it's roughly the same trace. There are some differences, though > those are likely due to me finding a new way to trigger the issue. (My > laptop has a button to turn the WiFi/Bluetooth on and off. Hitting > that and causing a disconnect of the internal Bluetooth connector > triggers the same issue without going through a suspend/resume cycle.) Hi Ray, This issue has actually been resolved, see the patch at: http://lkml.org/lkml/2007/5/16/149 [ We've slightly altered the locking scheme, but it's also good to know that converting hci_notifier to a blocking notifier doesn't cause any troubles either. If this is fine with other drivers too, this could actually be a separate patch. ] I'll also soon send that patch to Andrew, will Cc you too. Thanks, Satyam - 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/