Return-path: Received: from mail-we0-f169.google.com ([74.125.82.169]:39679 "EHLO mail-we0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753132AbaFMXPA (ORCPT ); Fri, 13 Jun 2014 19:15:00 -0400 Received: by mail-we0-f169.google.com with SMTP id t60so3501097wes.14 for ; Fri, 13 Jun 2014 16:14:59 -0700 (PDT) Message-ID: <539B85F0.3090004@gmail.com> (sfid-20140614_011504_664717_150B64C7) Date: Sat, 14 Jun 2014 01:14:56 +0200 From: Mathy Vanhoef MIME-Version: 1.0 To: Felix Fietkau , "John W. Linville" CC: linux-wireless@vger.kernel.org, Jiri Slaby , Nick Kossifidis , "Luis R. Rodriguez" , ath5k-devel@lists.ath5k.org Subject: Re: [PATCH 2/2] ath5k: capture CCK and OFDM restarts References: <539B7019.1050801@gmail.com> <539B7639.30104@openwrt.org> In-Reply-To: <539B7639.30104@openwrt.org> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 14/06/2014 0:07, Felix Fietkau wrote: > On 2014-06-13 23:41, Mathy Vanhoef wrote: >> Hi all, >> >> This patch allows users to see CCK and OFDM restarts when FIF_FCSFAIL is set. >> Without this patch only the stronger frame (causing the restart) would be >> visible. >> >> The patch has been tested using our reactive jammer. The prefix of the weaker >> frame is being correctly passed on as a frame with bad CRC! >> -- >> From: "Mathy Vanhoef" >> >> Treat frames that underwent a CCK or OFDM restart as frames with an invalid CRC. >> >> Signed-off-by: Mathy Vanhoef >> --- >> drivers/net/wireless/ath/ath5k/base.c | 14 +++++++++++++- >> 1 file changed, 13 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c >> index 39ba642..1bbc850 100644 >> --- a/drivers/net/wireless/ath/ath5k/base.c >> +++ b/drivers/net/wireless/ath/ath5k/base.c >> @@ -1462,7 +1462,19 @@ ath5k_receive_frame_ok(struct ath5k_hw *ah, struct ath5k_rx_status *rs) >> ah->stats.rxerr_phy++; >> if (rs->rs_phyerr > 0 && rs->rs_phyerr < 32) >> ah->stats.rxerr_phy_code[rs->rs_phyerr]++; >> - return false; >> + >> + /* >> + * Threat packets that underwent a CCK of OFDM reset as having a bad CRC. >> + * These restarts happen when the radio resynchronizes to a stronger frame >> + * while receiving a weaker frame. Here we receive the prefix of the weak >> + * frame. Since these are incomplete packets, mark their CRC as invalid. >> + */ >> + if (rs->rs_phyerr == AR5K_RX_PHY_ERROR_OFDM_RESTART || >> + rs->rs_phyerr == AR5K_RX_PHY_ERROR_CCK_RESTART) { >> + rs->rs_status |= AR5K_RXERR_CRC; >> + rs->rs_status &= (~AR5K_RXERR_PHY); > Unnecessary braces > >> + } > What about the return statement you removed, shouldn't you add that back > for the 'else' case? > > - Felix > Just saw a spelling mistake in the comment, s/Threat/Treat. The parenthesis around `(~AR5K_RXERR_PHY)` can indeed be removed. I suppose it's best to keep the return statement (I don't know precisely why it appears so early in the function, but it likely has a good reason). Updated patch is included below. -- From: "Mathy Vanhoef" Treat frames that underwent a CCK or OFDM restart as frames with an invalid CRC. Signed-off-by: Mathy Vanhoef --- drivers/net/wireless/ath/ath5k/base.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c index 4b18434..6e7c636 100644 --- a/drivers/net/wireless/ath/ath5k/base.c +++ b/drivers/net/wireless/ath/ath5k/base.c @@ -1457,7 +1457,20 @@ ath5k_receive_frame_ok(struct ath5k_hw *ah, struct ath5k_rx_status *rs) ah->stats.rxerr_phy++; if (rs->rs_phyerr > 0 && rs->rs_phyerr < 32) ah->stats.rxerr_phy_code[rs->rs_phyerr]++; - return false; + + /* + * Treat packets that underwent a CCK of OFDM reset as having a bad CRC. + * These restarts happen when the radio resynchronizes to a stronger frame + * while receiving a weaker frame. Here we receive the prefix of the weak + * frame. Since these are incomplete packets, mark their CRC as invalid. + */ + if (rs->rs_phyerr == AR5K_RX_PHY_ERROR_OFDM_RESTART || + rs->rs_phyerr == AR5K_RX_PHY_ERROR_CCK_RESTART) { + rs->rs_status |= AR5K_RXERR_CRC; + rs->rs_status &= ~AR5K_RXERR_PHY; + } else { + return false; + } } if (rs->rs_status & AR5K_RXERR_DECRYPT) { /* -- 1.8.1.2