Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752655Ab2JHM6m (ORCPT ); Mon, 8 Oct 2012 08:58:42 -0400 Received: from cantor2.suse.de ([195.135.220.15]:54747 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220Ab2JHM6k (ORCPT ); Mon, 8 Oct 2012 08:58:40 -0400 Date: Mon, 08 Oct 2012 14:58:38 +0200 Message-ID: From: Takashi Iwai To: Daniel J Blueman Cc: Dave Airlie , Linux Kernel , alsa-devel@alsa-project.org Subject: Re: [3.6-rc7] switcheroo race with Intel HDA... In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.1 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2211 Lines: 78 Hi Daniel, sorry for the late reply. I'm just back from vacation. At Tue, 25 Sep 2012 13:20:05 +0800, Daniel J Blueman wrote: > > On my Macbook with a discrete Nvidia GPU, there is a race between > selecting the integrated GPU and putting the discrete GPU into D3 [1], > reliably causing a kernel oops [2]. > > Introducing a delay of ~1s between the calls prevents this. When the > second 'OFF' write path executes, it looks like struct azx at > card->private_data hasn't yet been allocated yet [3], so there is > likely some locking missing. It's rather pci_get_drvdata() returning NULL (i.e. card is NULL, thus card->private_data causes Oops). Could you check the patch like below and see whether you get a kernel warning (but no Oops) or the problem gets fixed by shifting the assignment of pci drvdata? thanks, Takashi --- diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index f09ff6c..152f9e1 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -2609,9 +2609,15 @@ static void azx_vs_set_state(struct pci_dev *pci, enum vga_switcheroo_state state) { struct snd_card *card = pci_get_drvdata(pci); - struct azx *chip = card->private_data; + struct azx *chip; bool disabled; + if (WARN_ON(!card)) + return; + + chip = card->private_data; + if (WARN_ON(!chip)) + return; if (chip->init_failed) return; @@ -3314,6 +3320,7 @@ static int __devinit azx_probe(struct pci_dev *pci, } snd_card_set_dev(card, &pci->dev); + pci_set_drvdata(pci, card); err = azx_create(card, pci, dev, pci_id->driver_data, &chip); if (err < 0) @@ -3340,8 +3347,6 @@ static int __devinit azx_probe(struct pci_dev *pci, goto out_free; } - pci_set_drvdata(pci, card); - if (pci_dev_run_wake(pci)) pm_runtime_put_noidle(&pci->dev); @@ -3350,6 +3355,7 @@ static int __devinit azx_probe(struct pci_dev *pci, out_free: snd_card_free(card); + pci_set_drvdata(pci, NULL); return err; } -- 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/