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https://github.com/Divested-Mobile/DivestOS-Build.git
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161 lines
6.4 KiB
Diff
161 lines
6.4 KiB
Diff
From 1d147bfa64293b2723c4fec50922168658e613ba Mon Sep 17 00:00:00 2001
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From: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
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Date: Thu, 20 Feb 2014 09:22:11 +0200
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Subject: mac80211: fix AP powersave TX vs. wakeup race
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There is a race between the TX path and the STA wakeup: while
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a station is sleeping, mac80211 buffers frames until it wakes
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up, then the frames are transmitted. However, the RX and TX
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path are concurrent, so the packet indicating wakeup can be
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processed while a packet is being transmitted.
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This can lead to a situation where the buffered frames list
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is emptied on the one side, while a frame is being added on
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the other side, as the station is still seen as sleeping in
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the TX path.
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As a result, the newly added frame will not be send anytime
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soon. It might be sent much later (and out of order) when the
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station goes to sleep and wakes up the next time.
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Additionally, it can lead to the crash below.
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Fix all this by synchronising both paths with a new lock.
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Both path are not fastpath since they handle PS situations.
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In a later patch we'll remove the extra skb queue locks to
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reduce locking overhead.
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BUG: unable to handle kernel
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NULL pointer dereference at 000000b0
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IP: [<ff6f1791>] ieee80211_report_used_skb+0x11/0x3e0 [mac80211]
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*pde = 00000000
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Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
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EIP: 0060:[<ff6f1791>] EFLAGS: 00210282 CPU: 1
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EIP is at ieee80211_report_used_skb+0x11/0x3e0 [mac80211]
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EAX: e5900da0 EBX: 00000000 ECX: 00000001 EDX: 00000000
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ESI: e41d00c0 EDI: e5900da0 EBP: ebe458e4 ESP: ebe458b0
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DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
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CR0: 8005003b CR2: 000000b0 CR3: 25a78000 CR4: 000407d0
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DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
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DR6: ffff0ff0 DR7: 00000400
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Process iperf (pid: 3934, ti=ebe44000 task=e757c0b0 task.ti=ebe44000)
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iwlwifi 0000:02:00.0: I iwl_pcie_enqueue_hcmd Sending command LQ_CMD (#4e), seq: 0x0903, 92 bytes at 3[3]:9
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Stack:
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e403b32c ebe458c4 00200002 00200286 e403b338 ebe458cc c10960bb e5900da0
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ff76a6ec ebe458d8 00000000 e41d00c0 e5900da0 ebe458f0 ff6f1b75 e403b210
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ebe4598c ff723dc1 00000000 ff76a6ec e597c978 e403b758 00000002 00000002
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Call Trace:
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[<ff6f1b75>] ieee80211_free_txskb+0x15/0x20 [mac80211]
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[<ff723dc1>] invoke_tx_handlers+0x1661/0x1780 [mac80211]
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[<ff7248a5>] ieee80211_tx+0x75/0x100 [mac80211]
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[<ff7249bf>] ieee80211_xmit+0x8f/0xc0 [mac80211]
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[<ff72550e>] ieee80211_subif_start_xmit+0x4fe/0xe20 [mac80211]
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[<c149ef70>] dev_hard_start_xmit+0x450/0x950
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[<c14b9aa9>] sch_direct_xmit+0xa9/0x250
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[<c14b9c9b>] __qdisc_run+0x4b/0x150
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[<c149f732>] dev_queue_xmit+0x2c2/0xca0
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Cc: stable@vger.kernel.org
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Reported-by: Yaara Rozenblum <yaara.rozenblum@intel.com>
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Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
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Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
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[reword commit log, use a separate lock]
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Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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---
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net/mac80211/sta_info.c | 4 ++++
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net/mac80211/sta_info.h | 7 +++----
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net/mac80211/tx.c | 15 +++++++++++++++
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3 files changed, 22 insertions(+), 4 deletions(-)
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diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
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index decd30c..62a5f08 100644
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--- a/net/mac80211/sta_info.c
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+++ b/net/mac80211/sta_info.c
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@@ -330,6 +330,7 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
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rcu_read_unlock();
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spin_lock_init(&sta->lock);
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+ spin_lock_init(&sta->ps_lock);
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INIT_WORK(&sta->drv_unblock_wk, sta_unblock);
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INIT_WORK(&sta->ampdu_mlme.work, ieee80211_ba_session_work);
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mutex_init(&sta->ampdu_mlme.mtx);
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@@ -1109,6 +1110,8 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
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skb_queue_head_init(&pending);
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+ /* sync with ieee80211_tx_h_unicast_ps_buf */
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+ spin_lock(&sta->ps_lock);
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/* Send all buffered frames to the station */
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for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
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int count = skb_queue_len(&pending), tmp;
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@@ -1128,6 +1131,7 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
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}
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ieee80211_add_pending_skbs_fn(local, &pending, clear_sta_ps_flags, sta);
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+ spin_unlock(&sta->ps_lock);
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/* This station just woke up and isn't aware of our SMPS state */
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if (!ieee80211_smps_is_restrictive(sta->known_smps_mode,
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diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
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index d77ff70..d3a6d82 100644
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--- a/net/mac80211/sta_info.h
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+++ b/net/mac80211/sta_info.h
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@@ -267,6 +267,7 @@ struct ieee80211_tx_latency_stat {
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* @drv_unblock_wk: used for driver PS unblocking
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* @listen_interval: listen interval of this station, when we're acting as AP
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* @_flags: STA flags, see &enum ieee80211_sta_info_flags, do not use directly
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+ * @ps_lock: used for powersave (when mac80211 is the AP) related locking
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* @ps_tx_buf: buffers (per AC) of frames to transmit to this station
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* when it leaves power saving state or polls
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* @tx_filtered: buffers (per AC) of frames we already tried to
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@@ -356,10 +357,8 @@ struct sta_info {
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/* use the accessors defined below */
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unsigned long _flags;
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- /*
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- * STA powersave frame queues, no more than the internal
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- * locking required.
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- */
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+ /* STA powersave lock and frame queues */
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+ spinlock_t ps_lock;
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struct sk_buff_head ps_tx_buf[IEEE80211_NUM_ACS];
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struct sk_buff_head tx_filtered[IEEE80211_NUM_ACS];
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unsigned long driver_buffered_tids;
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diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
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index 97a02d3..4080c61 100644
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--- a/net/mac80211/tx.c
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+++ b/net/mac80211/tx.c
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@@ -478,6 +478,20 @@ ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
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sta->sta.addr, sta->sta.aid, ac);
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if (tx->local->total_ps_buffered >= TOTAL_MAX_TX_BUFFER)
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purge_old_ps_buffers(tx->local);
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+
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+ /* sync with ieee80211_sta_ps_deliver_wakeup */
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+ spin_lock(&sta->ps_lock);
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+ /*
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+ * STA woke up the meantime and all the frames on ps_tx_buf have
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+ * been queued to pending queue. No reordering can happen, go
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+ * ahead and Tx the packet.
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+ */
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+ if (!test_sta_flag(sta, WLAN_STA_PS_STA) &&
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+ !test_sta_flag(sta, WLAN_STA_PS_DRIVER)) {
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+ spin_unlock(&sta->ps_lock);
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+ return TX_CONTINUE;
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+ }
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+
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if (skb_queue_len(&sta->ps_tx_buf[ac]) >= STA_MAX_TX_BUFFER) {
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struct sk_buff *old = skb_dequeue(&sta->ps_tx_buf[ac]);
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ps_dbg(tx->sdata,
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@@ -492,6 +506,7 @@ ieee80211_tx_h_unicast_ps_buf(struct ieee80211_tx_data *tx)
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info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
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info->flags &= ~IEEE80211_TX_TEMPORARY_FLAGS;
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skb_queue_tail(&sta->ps_tx_buf[ac], tx->skb);
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+ spin_unlock(&sta->ps_lock);
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if (!timer_pending(&local->sta_cleanup))
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mod_timer(&local->sta_cleanup,
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--
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cgit v1.1
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