Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754462AbZG2MCW (ORCPT ); Wed, 29 Jul 2009 08:02:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754445AbZG2MCV (ORCPT ); Wed, 29 Jul 2009 08:02:21 -0400 Received: from mail-ew0-f226.google.com ([209.85.219.226]:51587 "EHLO mail-ew0-f226.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754438AbZG2MCU (ORCPT ); Wed, 29 Jul 2009 08:02:20 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=sender:message-id:date:from:reply-to:user-agent:mime-version:to:cc :subject:references:in-reply-to:content-type :content-transfer-encoding; b=VI41RLu220QpGk8X3phM3pT2EoBQnWuRdb/7QbWeXWflF6H+YV1awsfWw/7EhdS87P hEmHgMrq5Xm2AsHDG4fWl/K7pnbL3REbwQkVFA9do+TRld8jvGLRfRoBGNuM7YjWDWEG O8V9vuW2F/4tVcQOZiEjaAVCBH/DLtPINbOBY= Message-ID: <4A703A43.8050808@googlemail.com> Date: Wed, 29 Jul 2009 13:02:11 +0100 From: Alan Jenkins Reply-To: alan-jenkins@tuffmail.co.uk User-Agent: Thunderbird 2.0.0.21 (X11/20090318) MIME-Version: 1.0 To: Corentin Chary CC: Pekka Enberg , linux-kernel@vger.kernel.org Subject: Re: eeepc_hotkey rmmod issues References: <9b2b86520907290301w79d5bfa5j27c7e0142cc44ba9@mail.gmail.com> <71cd59b00907290321i50a51790ld2ba87cb2c61abc7@mail.gmail.com> In-Reply-To: <71cd59b00907290321i50a51790ld2ba87cb2c61abc7@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3886 Lines: 104 On 7/29/09, Corentin Chary wrote: > On Wed, Jul 29, 2009 at 12:01 PM, Alan > Jenkins wrote: >> On 7/28/09, Corentin Chary wrote: >>> On Tue, Jul 28, 2009 at 9:19 PM, Alan >>> Jenkins wrote: >>>> But we should still fix the underlying problem. It sounds like >>>> there's a narrow danger window on module unload. And it's still there >>>> in 2.6.31-rc4: >>>> >>>> 1019 static void eeepc_rfkill_exit(void) >>>> 1020 { >>>> 1021 eeepc_unregister_rfkill_notifier("\\_SB.PCI0.P0P6"); >>>> 1022 eeepc_unregister_rfkill_notifier("\\_SB.PCI0.P0P7"); >>>> 1023 if (ehotk->wlan_rfkill) >>>> 1024 rfkill_unregister(ehotk->wlan_rfkill); >>>> >>>> Really we need to perform these unregistrations "at the same time". >>>> The rfkill device relies on the notifier, but the notifier callback >>>> also uses the rfkill device. I guess we will need to a mutex to >>>> synchronize unregistration (and registration). >>> >>> I think 2.6.31 is ok, >> >>> In 2.6.30, we called eeepc_unregister_rfkill_notifier after >>> rfkill_free, which was an error because >>> the notifier callback uses the rfkill device. >> >> Ok. I don't see how that causes Luciano's errors. So I guess he was >> right to blame the wireless driver. > > If he was using 2.6.30, then : > eeepc_unregister_rfkill_notifier() was called after rfkill_unregister() > And the callback was still registered after rfkill_unregister(), *Ooops* > > In 2.6.31 we first unregister the callback, and then rfkill, so rmmod > should works. > >>> But I believe that the rfkill device can work without the notifier >>> (which is an acpi notifier). >> >> I don't think it can. >> >> If the rfkill device is set to "soft blocked", the pci device is >> removed. If the acpi notifier is not called, the pci driver (e.g. >> ath5k) won't realise the device is gone. The network device (e.g. >> wlan0) will remain present, but it won't work. > > Hum, there is a misunderstanding here. What I mean is : I think > eeepc_rfkill_exit(void) is ok in 2.6.31 (Luciano used 2.6.30). > > And eeepc_rfkill_exit() is only called on rmmod eeepc-laptop > > Commit 7de39389d8f61aa517ce2a8b4d925acc62696ae5 did a lot of > change in rfkill code. > >> So I believe there's a circular dependency which we need to resolve. >> Would you like me to write a patch for it? > > It's possible that I miss the issue here, so go ahead :) Thanks :) Here is a test case to show the race I am talking about diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c index ec560f1..c478db5 100644 --- a/drivers/platform/x86/eeepc-laptop.c +++ b/drivers/platform/x86/eeepc-laptop.c @@ -1020,6 +1020,17 @@ static void eeepc_rfkill_exit(void) { eeepc_unregister_rfkill_notifier("\\_SB.PCI0.P0P6"); eeepc_unregister_rfkill_notifier("\\_SB.PCI0.P0P7"); + + // + // Simulated error + // Imagine that userspace set the wifi to "soft blocked" at this exact moment + // (or the wireless toggle key was pressed) + // + // The PCI device will disappear, but we will not see any notification + // + set_acpi(CM_ASL_WLAN, 0); + rfkill_set_sw_state(ehotk->wlan_rfkill, true); + if (ehotk->wlan_rfkill) rfkill_unregister(ehotk->wlan_rfkill); if (ehotk->bluetooth_rfkill) If you unload eeepc-laptop with this simulated race, the wireless interface stays around but stops working. [ 191.391155] ath5k phy0: can't reset hardware (-5) [ 191.432983] ath5k phy0: failed to wakeup the MAC Chip [ 196.940835] __ratelimit: 21 callbacks suppressed Alan -- 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/