Return-path: Received: from mail-it0-f42.google.com ([209.85.214.42]:33961 "EHLO mail-it0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932796AbdIFPFI (ORCPT ); Wed, 6 Sep 2017 11:05:08 -0400 Received: by mail-it0-f42.google.com with SMTP id f199so13811648ita.1 for ; Wed, 06 Sep 2017 08:05:08 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1504702728.13457.17.camel@sipsolutions.net> References: <1504702728.13457.17.camel@sipsolutions.net> From: Matteo Croce Date: Wed, 6 Sep 2017 17:04:26 +0200 Message-ID: (sfid-20170906_170612_855952_816D32B8) Subject: Re: hung task in mac80211 To: Johannes Berg Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-wireless-owner@vger.kernel.org List-ID: On Wed, Sep 6, 2017 at 2:58 PM, Johannes Berg wrote: > On Wed, 2017-09-06 at 13:57 +0200, Matteo Croce wrote: > >> I have an hung task on vanilla 4.13 kernel which I haven't on 4.12. >> The problem is present both on my AP and on my notebook, >> so it seems it affects AP and STA mode as well. >> The generated messages are: >> >> INFO: task kworker/u16:6:120 blocked for more than 120 seconds. >> Not tainted 4.13.0 #57 >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this >> message. >> kworker/u16:6 D 0 120 2 0x00000000 >> Workqueue: phy0 ieee80211_ba_session_work [mac80211] >> Call Trace: >> ? __schedule+0x174/0x5b0 >> ? schedule+0x31/0x80 >> ? schedule_preempt_disabled+0x9/0x10 >> ? __mutex_lock.isra.2+0x163/0x480 >> ? select_task_rq_fair+0xb9f/0xc60 >> ? __ieee80211_start_rx_ba_session+0x135/0x4d0 [mac80211] >> ? __ieee80211_start_rx_ba_session+0x135/0x4d0 [mac80211] > > Yeah - obviously as Stefano found, both take &sta->ampdu_mlme.mtx. > > Can you try this? > > diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c > index 2b36eff5d97e..d8d32776031e 100644 > --- a/net/mac80211/agg-rx.c > +++ b/net/mac80211/agg-rx.c > @@ -245,10 +245,10 @@ static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *d > ieee80211_tx_skb(sdata, skb); > } > > -void __ieee80211_start_rx_ba_session(struct sta_info *sta, > - u8 dialog_token, u16 timeout, > - u16 start_seq_num, u16 ba_policy, u16 tid, > - u16 buf_size, bool tx, bool auto_seq) > +void ___ieee80211_start_rx_ba_session(struct sta_info *sta, > + u8 dialog_token, u16 timeout, > + u16 start_seq_num, u16 ba_policy, u16 tid, > + u16 buf_size, bool tx, bool auto_seq) > { > struct ieee80211_local *local = sta->sdata->local; > struct tid_ampdu_rx *tid_agg_rx; > @@ -267,7 +267,7 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta, > ht_dbg(sta->sdata, > "STA %pM requests BA session on unsupported tid %d\n", > sta->sta.addr, tid); > - goto end_no_lock; > + goto end; > } > > if (!sta->sta.ht_cap.ht_supported) { > @@ -275,14 +275,14 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta, > "STA %pM erroneously requests BA session on tid %d w/o QoS\n", > sta->sta.addr, tid); > /* send a response anyway, it's an error case if we get here */ > - goto end_no_lock; > + goto end; > } > > if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) { > ht_dbg(sta->sdata, > "Suspend in progress - Denying ADDBA request (%pM tid %d)\n", > sta->sta.addr, tid); > - goto end_no_lock; > + goto end; > } > > /* sanity check for incoming parameters: > @@ -296,7 +296,7 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta, > ht_dbg_ratelimited(sta->sdata, > "AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d\n", > sta->sta.addr, tid, ba_policy, buf_size); > - goto end_no_lock; > + goto end; > } > /* determine default buffer size */ > if (buf_size == 0) > @@ -311,7 +311,6 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta, > buf_size, sta->sta.addr); > > /* examine state machine */ > - mutex_lock(&sta->ampdu_mlme.mtx); > > if (test_bit(tid, sta->ampdu_mlme.agg_session_valid)) { > if (sta->ampdu_mlme.tid_rx_token[tid] == dialog_token) { > @@ -415,15 +414,25 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta, > __clear_bit(tid, sta->ampdu_mlme.unexpected_agg); > sta->ampdu_mlme.tid_rx_token[tid] = dialog_token; > } > - mutex_unlock(&sta->ampdu_mlme.mtx); > > -end_no_lock: > if (tx) > ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid, > dialog_token, status, 1, buf_size, > timeout); > } > > +void __ieee80211_start_rx_ba_session(struct sta_info *sta, > + u8 dialog_token, u16 timeout, > + u16 start_seq_num, u16 ba_policy, u16 tid, > + u16 buf_size, bool tx, bool auto_seq) > +{ > + mutex_lock(&sta->ampdu_mlme.mtx); > + ___ieee80211_start_rx_ba_session(sta, dialog_token, timeout, > + start_seq_num, ba_policy, tid, > + buf_size, tx, auto_seq); > + mutex_unlock(&sta->ampdu_mlme.mtx); > +} > + > void ieee80211_process_addba_request(struct ieee80211_local *local, > struct sta_info *sta, > struct ieee80211_mgmt *mgmt, > diff --git a/net/mac80211/ht.c b/net/mac80211/ht.c > index c92df492e898..198b2d3e56fd 100644 > --- a/net/mac80211/ht.c > +++ b/net/mac80211/ht.c > @@ -333,9 +333,9 @@ void ieee80211_ba_session_work(struct work_struct *work) > > if (test_and_clear_bit(tid, > sta->ampdu_mlme.tid_rx_manage_offl)) > - __ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid, > - IEEE80211_MAX_AMPDU_BUF, > - false, true); > + ___ieee80211_start_rx_ba_session(sta, 0, 0, 0, 1, tid, > + IEEE80211_MAX_AMPDU_BUF, > + false, true); > > if (test_and_clear_bit(tid + IEEE80211_NUM_TIDS, > sta->ampdu_mlme.tid_rx_manage_offl)) > diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h > index 2197c62a0a6e..9675814f64db 100644 > --- a/net/mac80211/ieee80211_i.h > +++ b/net/mac80211/ieee80211_i.h > @@ -1760,6 +1760,10 @@ void __ieee80211_start_rx_ba_session(struct sta_info *sta, > u8 dialog_token, u16 timeout, > u16 start_seq_num, u16 ba_policy, u16 tid, > u16 buf_size, bool tx, bool auto_seq); > +void ___ieee80211_start_rx_ba_session(struct sta_info *sta, > + u8 dialog_token, u16 timeout, > + u16 start_seq_num, u16 ba_policy, u16 tid, > + u16 buf_size, bool tx, bool auto_seq); > void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta, > enum ieee80211_agg_stop_reason reason); > void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata, > > johannes I confirm that this patch fixes the hang too. I'm curious to see if there are noticeable performance differences between the two solutions. Cheers, -- Matteo Croce per aspera ad upstream