Re: [PATCH 2/2] ath5k: capture CCK and OFDM restarts

[Felix Fietkau <nbd@openwrt.org>]

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" <vanhoefm@gmail.com>
> 
> Treat frames that underwent a CCK or OFDM restart as frames with an invalid CRC.
> 
> Signed-off-by: Mathy Vanhoef <vanhoefm@gmail.com>
> ---
>  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