From patchwork Mon Oct 21 12:11:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Krzysztof_Ha=C5=82asa?= X-Patchwork-Id: 11202119 X-Patchwork-Delegate: johannes@sipsolutions.net Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 41A4413BD for ; Mon, 21 Oct 2019 12:19:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C76F2173B for ; Mon, 21 Oct 2019 12:19:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=piap.pl header.i=@piap.pl header.b="hR8kZEAI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728595AbfJUMTK (ORCPT ); Mon, 21 Oct 2019 08:19:10 -0400 Received: from ni.piap.pl ([195.187.100.5]:48172 "EHLO ni.piap.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728540AbfJUMTJ (ORCPT ); Mon, 21 Oct 2019 08:19:09 -0400 Received: from t19.piap.pl (OSB1819.piap.pl [10.0.9.19]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ni.piap.pl (Postfix) with ESMTPSA id 8F1E7443597; Mon, 21 Oct 2019 14:11:31 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 ni.piap.pl 8F1E7443597 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=piap.pl; s=mail; t=1571659891; bh=2l3g9AQNQvoNkKc40D1gZPWvLVs7AjrMyGTdwvpiyJo=; h=From:To:Cc:Subject:Date:From; b=hR8kZEAIxIvs7So3Xp8ANP/+MxjRK9eNSwNzAsIfbz4WyTzOfezCPLNASVzEbjKE/ Xmgf6XaIHh+QVaam4MXqyTCBgkFPrOD/s0rj5y+NPltuyessadSQT9ZDpelTGbhdIA kpb9cfzTBUWcVrbuoVt77n/RWsRRfubcxySgma+Y= From: khalasa@piap.pl (Krzysztof =?utf-8?q?Ha=C5=82asa?=) To: Johannes Berg Cc: "David S. Miller" , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: 802.11n IBSS: wlan0 stops receiving packets due to aggregation after sender reboot Date: Mon, 21 Oct 2019 14:11:30 +0200 Message-ID: MIME-Version: 1.0 X-KLMS-Rule-ID: 4 X-KLMS-Message-Action: skipped X-KLMS-AntiSpam-Status: not scanned, whitelist X-KLMS-AntiPhishing: not scanned, whitelist X-KLMS-AntiVirus: Kaspersky Security 8.0 for Linux Mail Server, version 8.0.1.721, not scanned, whitelist Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Johannes, it seems I've encountered a bug in mac80211 RX aggregation handler. The hw is a pair of stations using AR9580 (PCI ID 168c:0033) PCIe adapters. Linux 5.4-rc4. The driver shows the chip is Atheros AR9300 Rev:4. I'm using (on both ends): iw wlan0 set type ibss ip link set wlan0 up iw dev wlan0 ibss join $ESSID $FREQ HT20 The problem manifests itself after one of the stations is restarted (or the ath9k driver is reloaded, or a station is out of range for some time etc). It appears that the mac80211 RX aggregation code sets a new aggregation "session" at the remote station's request, but the head_seq_num (the sequence number the receiver expects to receive) isn't reset. I've added some debugging code to ___ieee80211_start_rx_ba_session() and ieee80211_sta_manage_reorder_buf() and it produced the following: Both stations boot and join the IBSS, packets get through: [ 61.123131] AGG RX OK: ssn 1 [ 61.125346] SEQ OK: 1 vs 1 [ 61.125484] SEQ OK: 2 vs 2 [ 62.100841] SEQ OK: 3 vs 3 ... [ 180.124210] SEQ OK: 130 vs 130 [ 181.123888] SEQ OK: 131 vs 131 [ 182.126046] SEQ OK: 132 vs 132 Now I'm rebooting the remote station. It joins IBSS, packets can be seen on mon0 monitoring interface (on the local station), but they aren't arriving on wlan0: [ 192.131102] SEQ BAD: 0 vs 133 [ 192.151243] AGG RX no change - OK: ssn 1 [ 192.242760] SEQ BAD: 1 vs 133 [ 193.133819] SEQ BAD: 2 vs 133 [ 193.272802] SEQ BAD: 3 vs 133 ... [ 421.272374] SEQ BAD: 130 vs 133 [ 421.303630] SEQ BAD: 131 vs 133 [ 422.327924] SEQ BAD: 132 vs 133 Then the sequence number catches up and the communication is reestablished: [ 423.167023] SEQ OK: 133 vs 133 [ 423.169061] SEQ OK: 134 vs 134 [ 423.351618] SEQ OK: 135 vs 135 I'll attach a patch in a separate mail but I'm not sure if it's the optimal fix - one packet (the "SEQ BAD: 0 vs 133) is still dropped, and I guess it won't work if the sender decides to not request aggregation anymore. Comments? The debugging code: --- a/net/mac80211/agg-rx.c +++ b/net/mac80211/agg-rx.c @@ -354,9 +354,10 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta, */ rcu_read_lock(); tid_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]); - if (tid_rx && tid_rx->timeout == timeout) + if (tid_rx && tid_rx->timeout == timeout) { status = WLAN_STATUS_SUCCESS; - else + printk(KERN_DEBUG "AGG RX no change - OK: ssn %u\n", start_seq_num); + } else status = WLAN_STATUS_REQUEST_DECLINED; rcu_read_unlock(); goto end; @@ -434,6 +437,7 @@ void ___ieee80211_start_rx_ba_session(struct sta_info *sta, tid_agg_rx->tid = tid; tid_agg_rx->sta = sta; status = WLAN_STATUS_SUCCESS; + printk(KERN_DEBUG "AGG RX OK: ssn %u\n", start_seq_num); /* activate it for RX */ rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx); --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -1298,9 +1298,11 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_sub_if_data *sdata /* frame with out of date sequence number */ if (ieee80211_sn_less(mpdu_seq_num, head_seq_num)) { + printk(KERN_DEBUG "SEQ BAD: %u vs %u\n", mpdu_seq_num, head_seq_num); dev_kfree_skb(skb); goto out; - } + } else + printk(KERN_DEBUG "SEQ OK: %u vs %u\n", mpdu_seq_num, head_seq_num); /* * If frame the sequence number exceeds our buffering window