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Subject: Re: [PATCH] iwlwifi: do not nulify ctx->vif on reset
From: Johannes Berg <johannes@sipsolutions.net>
To: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Wey-Yi Guy <wey-yi.w.guy@intel.com>,
	Intel Linux Wireless <ilw@linux.intel.com>,
	linux-wireless@vger.kernel.org
Date: Mon, 26 Mar 2012 11:08:26 +0200
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On Wed, 2012-03-14 at 09:14 +0100, Stanislaw Gruszka wrote:
> On Wed, Mar 14, 2012 at 08:07:48AM +0100, Stanislaw Gruszka wrote:
> > I'll update and recheck again.
> 
> On updated tree (head 035364916f75151b4b91ea53968c6beba7545317) devices
> stop working here on any forced reset during TX as well. There are
> messages like below in dmesg:
> 
> wlan3: dropped data frame to not associated station 00:00:00:00:00:00
> 
> And one time crash happened too, in:
> 
> (gdb) l *(iwl_remove_dynamic_key+0x1f0)
> 0x15e20 is in iwl_remove_dynamic_key (drivers/net/wireless/iwlwifi/iwl-agn-sta.c:1105).
> 1100		/*
> 1101		 * The device expects GTKs for station interfaces to be
> 1102		 * installed as GTKs for the AP station. If we have no
> 1103		 * station ID, then use the ap_sta_id in that case.
> 1104		 */
> 1105		if (vif->type == NL80211_IFTYPE_STATION && vif_priv->ctx)
> 1106			return vif_priv->ctx->ap_sta_id;
> 1107	
> 1108		return IWL_INVALID_STATION;
> 1109	}
> 
> To reproduce problems, I'm doing "ping -f 192.168.1.1" on one console
> and run script [1] on other console.

Ok so I finally got some time to look into this in some detail. It seems
that the driver assumes a few calls from mac80211 like key settings can
only happen while the vif pointers are valid, which is correct under
normal circumstances but due to races with HW reset it's not really true
there.

We could fix all of those, but it seems your patch is the better
approach. Wey, can you pick it up?

johannes