ath9k: drop spectral packets after processing them

Spectral packets are "bogus" packets and should not be further evaluated
by the RX path.

Statistics are added to keep track of these packets.
Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/debug.c

@@ -895,6 +895,7 @@ static ssize_t read_file_recv(struct file *file, char __user *user_buf,
 	RXS_ERR("RX-Bytes-All", rx_bytes_all);
 	RXS_ERR("RX-Beacons", rx_beacons);
 	RXS_ERR("RX-Frags", rx_frags);
+	RXS_ERR("RX-Spectral", rx_spectral);
 
 	if (len > size)
 		len = size;

drivers/net/wireless/ath/ath9k/debug.h

@@ -219,6 +219,7 @@ struct ath_tx_stats {
  * @rx_too_many_frags_err:  Frames dropped due to too-many-frags received.
  * @rx_beacons:  No. of beacons received.
  * @rx_frags:  No. of rx-fragements received.
+ * @rx_spectral: No of spectral packets received.
  */
 struct ath_rx_stats {
 	u32 rx_pkts_all;
@@ -237,6 +238,7 @@ struct ath_rx_stats {
 	u32 rx_too_many_frags_err;
 	u32 rx_beacons;
 	u32 rx_frags;
+	u32 rx_spectral;
 };
 
 struct ath_stats {

drivers/net/wireless/ath/ath9k/recv.c

@@ -1023,9 +1023,9 @@ static s8 fix_rssi_inv_only(u8 rssi_val)
 	return (s8) rssi_val;
 }
 
-
-static void ath_process_fft(struct ath_softc *sc, struct ieee80211_hdr *hdr,
-			    struct ath_rx_status *rs, u64 tsf)
+/* returns 1 if this was a spectral frame, even if not handled. */
+static int ath_process_fft(struct ath_softc *sc, struct ieee80211_hdr *hdr,
+			   struct ath_rx_status *rs, u64 tsf)
 {
 #ifdef CONFIG_ATH_DEBUG
 	struct ath_hw *ah = sc->sc_ah;
@@ -1044,7 +1044,14 @@ static void ath_process_fft(struct ath_softc *sc, struct ieee80211_hdr *hdr,
 	if (rs->rs_phyerr != ATH9K_PHYERR_RADAR &&
 	    rs->rs_phyerr != ATH9K_PHYERR_FALSE_RADAR_EXT &&
 	    rs->rs_phyerr != ATH9K_PHYERR_SPECTRAL)
-		return;
+		return 0;
+
+	/* check if spectral scan bit is set. This does not have to be checked
+	 * if received through a SPECTRAL phy error, but shouldn't hurt.
+	 */
+	radar_info = ((struct ath_radar_info *)&vdata[len]) - 1;
+	if (!(radar_info->pulse_bw_info & SPECTRAL_SCAN_BITMASK))
+		return 0;
 
 	/* Variation in the data length is possible and will be fixed later.
 	 * Note that we only support HT20 for now.
@@ -1053,14 +1060,7 @@ static void ath_process_fft(struct ath_softc *sc, struct ieee80211_hdr *hdr,
 	 */
 	if ((len > SPECTRAL_HT20_TOTAL_DATA_LEN + 2) ||
 	    (len < SPECTRAL_HT20_TOTAL_DATA_LEN - 1))
-		return;
-
-	/* check if spectral scan bit is set. This does not have to be checked
-	 * if received through a SPECTRAL phy error, but shouldn't hurt.
-	 */
-	radar_info = ((struct ath_radar_info *)&vdata[len]) - 1;
-	if (!(radar_info->pulse_bw_info & SPECTRAL_SCAN_BITMASK))
-		return;
+		return 1;
 
 	fft_sample.tlv.type = ATH_FFT_SAMPLE_HT20;
 	fft_sample.tlv.length = sizeof(fft_sample) - sizeof(fft_sample.tlv);
@@ -1093,7 +1093,7 @@ static void ath_process_fft(struct ath_softc *sc, struct ieee80211_hdr *hdr,
 		memcpy(&bins[32], &vdata[33], SPECTRAL_HT20_NUM_BINS - 32);
 		break;
 	default:
-		return;
+		return 1;
 	}
 
 	/* DC value (value in the middle) is the blind spot of the spectral
@@ -1115,6 +1115,9 @@ static void ath_process_fft(struct ath_softc *sc, struct ieee80211_hdr *hdr,
 	fft_sample.tsf = tsf;
 
 	ath_debug_send_fft_sample(sc, &fft_sample.tlv);
+	return 1;
+#else
+	return 0;
 #endif
 }
 
@@ -1202,8 +1205,12 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
 		    unlikely(tsf_lower - rs.rs_tstamp > 0x10000000))
 			rxs->mactime += 0x100000000ULL;
 
-		if ((rs.rs_status & ATH9K_RXERR_PHY))
-			ath_process_fft(sc, hdr, &rs, rxs->mactime);
+		if (rs.rs_status & ATH9K_RXERR_PHY) {
+			if (ath_process_fft(sc, hdr, &rs, rxs->mactime)) {
+				RX_STAT_INC(rx_spectral);
+				goto requeue_drop_frag;
+			}
+		}
 
 		retval = ath9k_rx_skb_preprocess(common, hw, hdr, &rs,
 						 rxs, &decrypt_error);