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Date: Fri, 3 Feb 2012 15:42:54 +0530
Message-ID: <CAD2nsn1UONGkFWvy=7Cb_QM6x4vr=cj_O2W9CWaB3vNRUgw5EQ@mail.gmail.com> (sfid-20120203_111259_998799_EA528751)
Subject: Re:
From: Mohammed Shafi <shafi.wireless@gmail.com>
To: Felix Fietkau <nbd@openwrt.org>
Cc: "John W. Linville" <linville@tuxdriver.com>,
	Laurent Bonnans <bonnans.l@gmail.com>,
	linux-wireless@vger.kernel.org
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Sender: linux-wireless-owner@vger.kernel.org

On Thu, Feb 2, 2012 at 5:58 PM, Felix Fietkau <nbd@openwrt.org> wrote:
> On 2012-02-02 6:37 AM, Mohammed Shafi wrote:
>> Hi Felix,
>>
>> On Wed, Feb 1, 2012 at 10:34 PM, Felix Fietkau <nbd@openwrt.org> wrote:
>>> On 2012-02-01 5:27 PM, John W. Linville wrote:
>>>> On Wed, Feb 01, 2012 at 04:44:08PM +0530, Mohammed Shafi wrote:
>>>>> On Tue, Jan 31, 2012 at 11:28 AM, Mohammed Shafi
>>>>> <shafi.wireless@gmail.com> wrote:
>>>>> > On Tue, Jan 31, 2012 at 1:13 AM, Laurent Bonnans <bonnans.l@gmail.com> wrote:
>>>>> >> Since the update from linux 3.2.1 to 3.2.2, dhcp stopped working on
>>>>> >> some APs on my laptop with an AR9285 Wireless card.
>>>>> >>
>>>>> >> dhcp works fine on an open wifi network but receives no response on a
>>>>> >> wep network I use. I haven't been able to test it on a third network
>>>>> >> for now.
>>>>> >
>>>>> > ?reverting ?"ath9k_hw: fix interpretation of the rx KeyMiss flag" does
>>>>> > helps. ?i ?need to analyze
>>>>> > if it exposes some real issue which need to be fixed.
>>>>> >
>>>>>
>>>>> this seems to be a problem in WEP alone, where the key miss is always
>>>>> set for this case and RX_FLAG_DECRYPTED is not set. mac80211 trys to
>>>>> decrypt, ?but fails due to ICV mismatch.
>>>>
>>>> OK...any way to differentiate this case at that point in the code?
>>>>
>>>> John
>>> Please try this patch:
>>>
>>> ---
>>> --- a/drivers/net/wireless/ath/ath9k/recv.c
>>> +++ b/drivers/net/wireless/ath/ath9k/recv.c
>>> @@ -823,6 +823,15 @@ static bool ath9k_rx_accept(struct ath_c
>>> ? ? ? ? ? ? ? ?(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_CRC | ATH9K_RXERR_MIC |
>>> ? ? ? ? ? ? ? ? ATH9K_RXERR_KEYMISS));
>>>
>>> + ? ? ? /*
>>> + ? ? ? ?* First 4 slots are reserved for WEP, and for packets using them,
>>> + ? ? ? ?* ATH9K_RXERR_KEYMISS can be reported even though decryption was
>>> + ? ? ? ?* successful, since no MAC address based key cache lookup was
>>> + ? ? ? ?* performed.
>>> + ? ? ? ?*/
>>> + ? ? ? if (rx_stats->rs_keyix < 4)
>>> + ? ? ? ? ? ? ? rx_stats->rs_status &= ~ATH9K_RXERR_KEYMISS;
>>> +
>>> ? ? ? ?if (!rx_stats->rs_datalen)
>>> ? ? ? ? ? ? ? ?return false;
>>> ? ? ? ? /*
>>
>>
>> unfortunately as the rx_keyix is always 'INVALID' (as obtained from
>> the descriptor) this check does not seems to help
> You're right. I read up on what the other codebases do here, and I have
> a better patch here:
>
> --- a/drivers/net/wireless/ath/ath9k/recv.c
> +++ b/drivers/net/wireless/ath/ath9k/recv.c
> @@ -823,6 +823,14 @@ static bool ath9k_rx_accept(struct ath_c
> ? ? ? ? ? ? ? ?(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_CRC | ATH9K_RXERR_MIC |
> ? ? ? ? ? ? ? ? ATH9K_RXERR_KEYMISS));
>
> + ? ? ? /*
> + ? ? ? ?* Key miss events are only relevant for pairwise keys where the
> + ? ? ? ?* descriptor does contain a valid key index. This has been observed
> + ? ? ? ?* mostly with CCMP encryption.
> + ? ? ? ?*/
> + ? ? ? if (rx_stats->rs_keyix == ATH9K_RXKEYIX_INVALID)
> + ? ? ? ? ? ? ? rx_stats->rs_status &= ~ATH9K_RXERR_KEYMISS;
> +
> ? ? ? ?if (!rx_stats->rs_datalen)
> ? ? ? ? ? ? ? ?return false;
> ? ? ? ? /*
>

this works for me (WEP key configured).

-- 
shafi