From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-io0-f169.google.com ([209.85.223.169]:56030 "EHLO mail-io0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751316AbdINRf5 (ORCPT ); Thu, 14 Sep 2017 13:35:57 -0400 Received: by mail-io0-f169.google.com with SMTP id z187so2333295ioz.12 for ; Thu, 14 Sep 2017 10:35:57 -0700 (PDT) Subject: Re: iwlwifi firmware load broken in current -git To: Srinath Mannam Cc: Bjorn Helgaas , Johannes Berg , Luca Coelho , "Grumbach, Emmanuel" , linuxwifi , "linux-wireless@vger.kernel.org" , "linux-pci@vger.kernel.org" References: <04c9b578-693c-1dc6-9f0f-904580231b21@kernel.dk> <1505232673.5400.243.camel@intel.com> <1505234187.5400.249.camel@coelho.fi> <4bcbcbc1-7c79-09f0-5071-bc2f53bf6574@kernel.dk> <1505246657.1974.11.camel@sipsolutions.net> From: Jens Axboe Message-ID: <8de8d1e2-1673-e1ff-d0ac-6d3bb03e9e99@kernel.dk> (sfid-20170914_193601_690183_159E6CAC) Date: Thu, 14 Sep 2017 11:35:54 -0600 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 09/14/2017 11:28 AM, Srinath Mannam wrote: > Hi Bjorn, > > On Thu, Sep 14, 2017 at 10:52 PM, Jens Axboe wrote: >> >> On 09/14/2017 11:11 AM, Bjorn Helgaas wrote: >>> [+cc linux-pci] >>> >>> On Thu, Sep 14, 2017 at 12:00 PM, Jens Axboe wrote: >>>> On 09/12/2017 02:04 PM, Johannes Berg wrote: >>>>> On Tue, 2017-09-12 at 13:43 -0600, Jens Axboe wrote: >>>>> >>>>>> CC'ing the guilty part and Bjorn. I'm assuming it's the >>>>>> pci_is_enabled() check, since the rest of the patch shouldn't have >>>>>> functional changes. >>>>> >>>>> and pci_enable_bridge() already checks if it's already enabled, but >>>>> still enables mastering in that case if it isn't: >>>>> >>>>> static void pci_enable_bridge(struct pci_dev *dev) >>>>> { >>>>> [...] >>>>> if (pci_is_enabled(dev)) { >>>>> if (!dev->is_busmaster) >>>>> pci_set_master(dev); >>>>> return; >>>>> } >>>>> >>>>> so I guess due to the new check we end up with mastering disabled, and >>>>> thus the firmware can't load since that's a DMA thing? >>>> >>>> Bjorn/Srinath, any input here? This is a regression that prevents wifi >>>> from working on a pretty standard laptop. It'd suck to have this be in >>>> -rc1. Seems like the trivial fix would be: >>>> >>>> >>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >>>> index b0002daa50f3..ffbe11dbdd61 100644 >>>> --- a/drivers/pci/pci.c >>>> +++ b/drivers/pci/pci.c >>>> @@ -1394,7 +1394,7 @@ static int pci_enable_device_flags(struct pci_dev *dev, unsigned long flags) >>>> return 0; /* already enabled */ >>>> >>>> bridge = pci_upstream_bridge(dev); >>>> - if (bridge && !pci_is_enabled(bridge)) >>>> + if (bridge) > With this change and keeping "mutex_lock(&pci_bridge_mutex);" in > pci_enable_bridge functoin will causes a nexted lock. Took a look, and looks like you are right. That code looks like a mess, fwiw. I'd strongly suggest that the bad commit is reverted until a proper solution is found, since the simple one-liner could potentially introduce a deadlock with your patch applied. -- Jens Axboe