SRU - LP #296285 - iwlagn: avoid sleep in softirq context

[Ben Collins]

Tim Gardner wrote:
>>From 8e80cc54c0b08f38cf1f9a66ebd96284b55f0d2f Mon Sep 17 00:00:00 2001
> From: John W. Linville <linville at tuxdriver.com>
> Date: Thu, 30 Oct 2008 13:59:16 -0400
> Subject: [PATCH] UBUNTU: SAUCE: iwlagn: avoid sleep in softirq context
>  LP: #286285
> 
> __ieee80211_tasklet_handler -> __ieee80211_rx ->
> 	__ieee80211_rx_handle_packet -> ieee80211_invoke_rx_handlers ->
> 	ieee80211_rx_h_decrypt -> ieee80211_crypto_tkip_decrypt ->
> 	ieee80211_tkip_decrypt_data -> iwl4965_mac_update_tkip_key ->
> 	iwl_scan_cancel_timeout -> msleep
> 
> Ooops!
> 
> Avoid the sleep by changing iwl_scan_cancel_timeout with
> iwl_scan_cancel and simply returning on failure if the scan persists.
> This will cause hardware decryption to fail and we'll handle a few more
> frames with software decryption.
> 
> Carry this as a SAUCE patch until applied by upstream. I suspect there will be a conflict
> if John fixes the spelling in the patch comment, e.g., decrpyption v.s. decryption.

ACK

> Signed-off-by: John W. Linville <linville at tuxdriver.com>
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
> ---
>  drivers/net/wireless/iwlwifi/iwl-agn.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
> index e01f048..7af4ca0 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-agn.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
> @@ -3266,7 +3266,12 @@ static void iwl4965_mac_update_tkip_key(struct ieee80211_hw *hw,
>  		return;
>  	}
>  
> -	iwl_scan_cancel_timeout(priv, 100);
> +	if (iwl_scan_cancel(priv)) {
> +		/* cancel scan failed, just live w/ bad key and rely
> +		   briefly on SW decrpyption */
> +		IWL_DEBUG_MAC80211("leave - failed to cancel scan\n");
> +		return;
> +	}
>  
>  	key_flags |= (STA_KEY_FLG_TKIP | STA_KEY_FLG_MAP_KEY_MSK);
>  	key_flags |= cpu_to_le16(keyconf->keyidx << STA_KEY_FLG_KEYID_POS);