Date:	Mon, 24 May 2010 14:52:16 -0700
From:	Greg KH <greg@...ah.com>
To:	"Luis R. Rodriguez" <lrodriguez@...eros.com>
Cc:	stable@...nel.org, Ming Lei <tom.leiming@...il.com>,
	linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
	"John W. Linville" <linville@...driver.com>,
	Johannes Berg <johannes@...solutions.net>
Subject: Re: [stable] [PATCH] Revert "ath9k: fix lockdep warning when
 unloading module" on stable kernels

On Wed, May 19, 2010 at 05:33:49PM -0400, Luis R. Rodriguez wrote:
> Johannes' patch 34e8950 titled:
> 
> 	mac80211: allow station add/remove to sleep
> 
> changed the way mac80211 adds and removes peers. The new
> sta_add() / sta_remove() callbacks allowed the driver callbacks
> to sleep. Johannes also ported ath9k to use sta_add() / sta_remove()
> via the patch 4ca7786 titled:
> 
> 	ath9k: convert to new station add/remove callbacks
> 
> but this patch forgot to address a change in locking issue which
> Ming Lei eventually found on his 2.6.33-wl #12 build. The 2.6.33-wl
> build includes code for the 802.11 subsystem for 2.6.34 though so did
> already have the above two patches (ath9k_sta_remove() on his trace),
> the 2.6.33 kernel did not however have these two patches. Ming eventually
> cured his lockdep warnign via the patch a9f042c titled:
> 
> 	ath9k: fix lockdep warning when unloading module
> 
> This went in to 2.6.34 and although it was not marked as a stable
> fix it did get trickled down and applied on both 2.6.33 and 2.6.32.
> 
> In review, the culprits:
> 
> 	mac80211: allow station add/remove to sleep
> git describe --contains 34e895075e21be3e21e71d6317440d1ee7969ad0
> v2.6.34-rc1~233^2~49^2~107
> 
> 	ath9k: convert to new station add/remove callbacks
> git describe --contains 4ca778605cfec53d8a689f0b57babb93b030c784
> v2.6.34-rc1~233^2~49^2~10
> 
> 	ath9k: fix lockdep warning when unloading module
> 
> This last one trickled down to 2.6.33 (OK), 2.6.33 (invalid) and 2.6.32 (invalid).
> 
> git describe --contains a9f042cbe5284f34ccff15f3084477e11b39b17b
> v2.6.34-rc2~48^2~77^2~7
> git describe --contains 0524bcfa80f1fffb4e1fe18a0a28900869a58a7c
> v2.6.33.2~125
> git describe --contains 0dcc9985f34aef3c60bffab3dfc7f7ba3748f35a
> v2.6.32.11~79
> 
> The patch titled "ath9k: fix lockdep warning when unloading module"
> should be reverted on both 2.6.33 and 2.6.32 as it is invalid and
> actually ended up causing the following warning:
> 
> ADDRCONF(NETDEV_CHANGE): wlan31: link becomes ready
> phy0: WMM queue=2 aci=0 acm=0 aifs=3 cWmin=15 cWmax=1023 txop=0
> phy0: WMM queue=3 aci=1 acm=0 aifs=7 cWmin=15 cWmax=1023 txop=0
> phy0: WMM queue=1 aci=2 acm=0 aifs=2 cWmin=7 cWmax=15 txop=94
> phy0: WMM queue=0 aci=3 acm=0 aifs=2 cWmin=3 cWmax=7 txop=47
> phy0: device now idle
> ------------[ cut here ]------------
> WARNING: at kernel/softirq.c:143 local_bh_enable_ip+0x7b/0xa0()
> Hardware name: 7660A14
> Modules linked in: ath9k(-) mac80211 ath cfg80211 <whatever-bleh-etc>
> Pid: 2003, comm: rmmod Not tainted 2.6.32.11 #6
> Call Trace:
>  [<ffffffff8105d178>] warn_slowpath_common+0x78/0xb0
>  [<ffffffff8105d1bf>] warn_slowpath_null+0xf/0x20
>  [<ffffffff81063f8b>] local_bh_enable_ip+0x7b/0xa0
>  [<ffffffff815121e4>] _spin_unlock_bh+0x14/0x20
>  [<ffffffffa034aea5>] ath_tx_node_cleanup+0x185/0x1b0 [ath9k]
>  [<ffffffffa0345597>] ath9k_sta_notify+0x57/0xb0 [ath9k]
>  [<ffffffffa02ac51a>] __sta_info_unlink+0x15a/0x260 [mac80211]
>  [<ffffffffa02ac658>] sta_info_unlink+0x38/0x60 [mac80211]
>  [<ffffffffa02b3fbe>] ieee80211_set_disassoc+0x1ae/0x210 [mac80211]
>  [<ffffffffa02b42d9>] ieee80211_mgd_deauth+0x109/0x110 [mac80211]
>  [<ffffffffa02ba409>] ieee80211_deauth+0x19/0x20 [mac80211]
>  [<ffffffffa028160e>] __cfg80211_mlme_deauth+0xee/0x130 [cfg80211]
>  [<ffffffff81118540>] ? init_object+0x50/0x90
>  [<ffffffffa0285429>] __cfg80211_disconnect+0x159/0x1d0 [cfg80211]
>  [<ffffffffa027125f>] cfg80211_netdev_notifier_call+0x10f/0x450 [cfg80211]
>  [<ffffffff81514ca7>] notifier_call_chain+0x47/0x90
>  [<ffffffff8107f501>] raw_notifier_call_chain+0x11/0x20
>  [<ffffffff81442d66>] call_netdevice_notifiers+0x16/0x20
>  [<ffffffff8144352d>] dev_close+0x4d/0xa0
>  [<ffffffff814439a8>] rollback_registered+0x48/0x120
>  [<ffffffff81443a9d>] unregister_netdevice+0x1d/0x70
>  [<ffffffffa02b6cc4>] ieee80211_remove_interfaces+0x84/0xc0 [mac80211]
>  [<ffffffffa02aa072>] ieee80211_unregister_hw+0x42/0xf0 [mac80211]
>  [<ffffffffa0347bde>] ath_detach+0x8e/0x180 [ath9k]
>  [<ffffffffa0347ce1>] ath_cleanup+0x11/0x50 [ath9k]
>  [<ffffffffa0351a2c>] ath_pci_remove+0x1c/0x20 [ath9k]
>  [<ffffffff8129d712>] pci_device_remove+0x32/0x60
>  [<ffffffff81332373>] __device_release_driver+0x53/0xb0
>  [<ffffffff81332498>] driver_detach+0xc8/0xd0
>  [<ffffffff81331405>] bus_remove_driver+0x85/0xe0
>  [<ffffffff81332a5a>] driver_unregister+0x5a/0x90
>  [<ffffffff8129da00>] pci_unregister_driver+0x40/0xb0
>  [<ffffffffa03518d0>] ath_pci_exit+0x10/0x20 [ath9k]
>  [<ffffffffa0353cd5>] ath9k_exit+0x9/0x2a [ath9k]
>  [<ffffffff81092838>] sys_delete_module+0x1a8/0x270
>  [<ffffffff8107ebe9>] ? up_read+0x9/0x10
>  [<ffffffff81011f82>] system_call_fastpath+0x16/0x1b
> ---[ end trace fad957019ffdd40b ]---
> phy0: Removed STA 00:22:6b:56:fd:e8
> phy0: Destroyed STA 00:22:6b:56:fd:e8
> wlan31: deauthenticating from 00:22:6b:56:fd:e8 by local choice (reason=3)
> ath9k 0000:16:00.0: PCI INT A disabled
> 
> The original lockdep fixed an issue where due to the new changes
> the driver was not disabling the bottom halves but it is incorrect
> to do this on the older kernels since IRQs are already disabled.
> 
> Cc: Ming Lei <tom.leiming@...il.com>
> Cc: Johannes Berg <johannes@...solutions.net>
> Cc: John W. Linville <linville@...driver.com>

For some reason, you never signed-off on this patch, why?  Care to send
me a "Signed-off-by:" line so I can add it?

thanks,

greg k-h
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