[Jaunty SRU] LP#345710 [v2: description modified] iwl3945: cancel rfkill_poll with sync when?the module is exiting

[Stefan Bader]

Hi Huaxu,

thanks for the work and sorry for being so late in response. It seems, by now 
the patch made it upstream as

commit 71d449b55abf5018d7c711b2b62abc0c083723c4
Author: Reinette Chatre <reinette.chatre at intel.com>
Date:   Mon Apr 20 14:37:01 2009 -0700

     iwl3945: use cancel_delayed_work_sync to cancel rfkill_poll

     Users reported lockup with work still trying to run
     after module has been unloaded.

     http://thread.gmane.org/gmane.linux.kernel.wireless.general/30594/focus=3060

     Signed-off-by: Reinette Chatre <reinette.chatre at intel.com>
     Reported-by: TJ <ubuntu at tjworld.net>
     Reported-by: Huaxu Wan <huaxu.wan at linux.intel.com>
     Signed-off-by: John W. Linville <linville at tuxdriver.com>


This looks even simpler by just syncing the cancellation. I will go on and try 
to get this version into SRU. Thanks again.

Stefan

Huaxu Wan wrote:
> From f3628f0ac6c9713afadaa9654815c37a294ce7e2 Mon Sep 17 00:00:00 2001
> From: Huaxu Wan <huaxu.wan at linux.intel.com>
> Date: Fri, 8 May 2009 07:36:58 -0400
> Subject: [PATCH] cancel rfkill_poll with sync when module is exiting
> 
> Re-write the patch due to there is no response from TJ.
> 
> When the the interface is down, a delayed work rfkill_poll is queued.
> This work must be canceled before the module is unloaded, or the OS would
> suffer a hard lock-up.
>  
> This patch fix the bug LP: #345710 by make sure the queued work is canceled.
> 
> 
> Original info:
> http://marc.info/?l=linux-wireless&m=123791044313158&w=2
> Bug: #345710
> 
> When the wireless interface is active and the iwl3945 module is unloaded the
> call to ieee80211_unregister_hw() would call iwl3945_mac_stop() which would
> restart the delayed workqueue for rfkill_poll. That workqueue had already been
> cancelled so when the next work item was run (2 seconds later) the system would
> suffer a hard lock-up because the module had been unloaded by then.
> 
> This patch implements STATUS_EXIT_PENDING checks in places where the rfkill_poll
> work is scheduled, and moves the final workqueue cancellation to occur after the
> call to ieee80211_unregister_hw().
> 
> Bug discovered, experienced and fix tested on my PC.
> 
> Signed-off-by: TJ <ubuntu at tjworld.net>
> Signed-off-by: Huaxu Wan <huaxu.wan at linux.intel.com>
> ---
>  drivers/net/wireless/iwlwifi/iwl3945-base.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
> index bb92db2..08c2a9d 100644
> --- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
> +++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
> @@ -8166,7 +8166,6 @@ static void __devexit iwl3945_pci_remove(struct pci_dev *pdev)
>  	sysfs_remove_group(&pdev->dev.kobj, &iwl3945_attribute_group);
>  
>  	iwl3945_rfkill_unregister(priv);
> -	cancel_delayed_work(&priv->rfkill_poll);
>  	iwl3945_dealloc_ucode_pci(priv);
>  
>  	if (priv->rxq.bd)
> @@ -8181,6 +8180,7 @@ static void __devexit iwl3945_pci_remove(struct pci_dev *pdev)
>  
>  	/*netif_stop_queue(dev); */
>  	flush_workqueue(priv->workqueue);
> +	cancel_delayed_work_sync(&priv->rfkill_poll);
>  
>  	/* ieee80211_unregister_hw calls iwl3945_mac_stop, which flushes
>  	 * priv->workqueue... so we can't take down the workqueue


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