Return-path: <linux-wireless-owner@vger.kernel.org>
Received: from mail-vw0-f42.google.com ([209.85.212.42]:57964 "EHLO
	mail-vw0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750977Ab1IQKcI convert rfc822-to-8bit (ORCPT
	<rfc822;linux-wireless@vger.kernel.org>);
	Sat, 17 Sep 2011 06:32:08 -0400
MIME-Version: 1.0
In-Reply-To: <877h57jwmh.fsf@tac.ki.iif.hu>
References: <877h57jwmh.fsf@tac.ki.iif.hu>
Date: Sat, 17 Sep 2011 06:32:05 -0400
Message-ID: <CA+5PVA5eJXzLHO=S9kaBt4_OzuJxJxAOpmm7ABVSu7bm1VjmdQ@mail.gmail.com> (sfid-20110917_123242_749706_2F90D964)
Subject: Re: mac80211 regression (deadlock) with built-in ipw2200
From: Josh Boyer <jwboyer@gmail.com>
To: Ferenc Wagner <wferi@niif.hu>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	"David S. Miller" <davem@davemloft.net>,
	"John W. Linville" <linville@tuxdriver.com>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-wireless-owner@vger.kernel.org
List-ID: <linux-wireless.vger.kernel.org>

On Sat, Sep 17, 2011 at 6:23 AM, Ferenc Wagner <wferi@niif.hu> wrote:
> Hi,
>
> As pointed out by git-bisect, commit ecb44335 (mac80211: fix
> suspend/resume races with unregister hw) broke booting on my ThinkPad
> R50e. Looks like the rtnl_lock() around rdev->wiphy.registered = true
> leads to a deadlock, possibly because ipw2200 is built-in in my
> config. ?Testing with the additional debug patch
>
> --- a/net/wireless/core.c
> +++ b/net/wireless/core.c
> @@ -616,9 +616,8 @@ int wiphy_register(struct wiphy *wiphy)
> ? ? ? ?if (res)
> ? ? ? ? ? ? ? ?goto out_rm_dev;
>
> - ? ? ? rtnl_lock();
> + ? ? ? WARN_ON(rtnl_is_locked());
> ? ? ? ?rdev->wiphy.registered = true;
> - ? ? ? rtnl_unlock();
> ? ? ? ?return 0;
>
> on top of c455ea4f (rc6+) leads to a working system with
>
> [ ? ?1.020738] ipw2200: Intel(R) PRO/Wireless 2200/2915 Network Driver, 1.2.2kmpr
> [ ? ?1.020812] ipw2200: Copyright(c) 2003-2006 Intel Corporation
> [ ? ?1.023406] ACPI: PCI Interrupt Link [LNKF] enabled at IRQ 11
> [ ? ?1.025717] ipw2200 0000:02:02.0: PCI INT A -> Link[LNKF] -> GSI 11 (level, low
> ) -> IRQ 11
> [ ? ?1.028048] ipw2200: Detected Intel PRO/Wireless 2200BG Network Connection
> [ ? ?1.148058] ------------[ cut here ]------------
> [ ? ?1.150393] WARNING: at net/wireless/core.c:619 wiphy_register+0x4c1/0x58c()
> [ ? ?1.152781] Hardware name: 1834S5G
> [ ? ?1.155126] Pid: 1, comm: swapper Not tainted 3.1.0-rc6+ #86
> [ ? ?1.157520] Call Trace:
> [ ? ?1.159871] ?[<c1028b98>] warn_slowpath_common+0x69/0x90
> [ ? ?1.162241] ?[<c13ee7a8>] ? wiphy_register+0x4c1/0x58c
> [ ? ?1.164617] ?[<c13ee7a8>] ? wiphy_register+0x4c1/0x58c
> [ ? ?1.166924] ?[<c1028be1>] warn_slowpath_null+0x22/0x24
> [ ? ?1.169230] ?[<c13ee7a8>] wiphy_register+0x4c1/0x58c
> [ ? ?1.171564] ?[<c12daad0>] ? ipw_net_init+0x1e6/0x2d0
> [ ? ?1.173890] ?[<c12da995>] ipw_net_init+0xab/0x2d0
> [ ? ?1.176173] ?[<c1375032>] register_netdevice+0x70/0x271
> [ ? ?1.178446] ?[<c137524e>] register_netdev+0x1b/0x28
> [ ? ?1.180688] ?[<c142f5b8>] ipw_pci_probe+0x7c3/0x891
> [ ? ?1.182892] ?[<c11a6f93>] local_pci_probe+0x40/0x9a
> [ ? ?1.185086] ?[<c11a7c98>] pci_device_probe+0x56/0x71
> [ ? ?1.187259] ?[<c128c902>] driver_probe_device+0x6c/0x177
> [ ? ?1.189453] ?[<c11a6ed9>] ? pci_match_device+0x80/0x85
> [ ? ?1.191615] ?[<c128ca79>] __driver_attach+0x6c/0x6e
> [ ? ?1.193794] ?[<c128c257>] bus_for_each_dev+0x4a/0x68
> [ ? ?1.195936] ?[<c128c7b4>] driver_attach+0x1e/0x20
> [ ? ?1.198043] ?[<c128ca0d>] ? driver_probe_device+0x177/0x177
> [ ? ?1.200151] ?[<c128bce5>] bus_add_driver+0x186/0x231
> [ ? ?1.202247] ?[<c11a7b3c>] ? pci_dev_put+0x16/0x16
> [ ? ?1.204320] ?[<c128cfac>] driver_register+0x6a/0x118
> [ ? ?1.206386] ?[<c120665f>] ? misc_register+0xc2/0x133
> [ ? ?1.208425] ?[<c15ee31e>] ? parse_early_options+0x25/0x25
> [ ? ?1.210423] ?[<c11a7e66>] __pci_register_driver+0x33/0x8c
> [ ? ?1.212393] ?[<c15ee31e>] ? parse_early_options+0x25/0x25
> [ ? ?1.214384] ?[<c160e0e8>] ipw_init+0x30/0x75
> [ ? ?1.216356] ?[<c15ee24c>] do_one_initcall+0x86/0x133
> [ ? ?1.218340] ?[<c160e0b8>] ? tun_init+0x8b/0x8b
> [ ? ?1.220315] ?[<c15ee31e>] ? parse_early_options+0x25/0x25
> [ ? ?1.222270] ?[<c15ee393>] kernel_init+0x75/0x10c
> [ ? ?1.224214] ?[<c14349b6>] kernel_thread_helper+0x6/0x10
> [ ? ?1.226124] ---[ end trace 4ef665623022622c ]---
> [ ? ?1.228121] ipw2200: Detected geography ZZR (14 802.11bg channels, 0 802.11a channels)
>
> in dmesg. ?It's a shoot in the dark, but register_netdev() issues
> rtnl_lock() before calling register_netdevice(), so wiphy_register()
> can't possibly acquire the rtnl mutex in the same call chain, or can
> it?

This is fixed here:

http://article.gmane.org/gmane.linux.kernel.wireless.general/77103

josh