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Commit 24a8fdad authored by Christian Lamparter's avatar Christian Lamparter Committed by John W. Linville
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mac80211: serialize rx path workers 

This patch addresses the issue of serialization between
the main rx path and various reorder release timers.

<http://www.spinics.net/lists/linux-wireless/msg57214.html

>

It converts the previously local "frames" queue into
a global rx queue [rx_skb_queue]. This way, everyone
(be it the main rx-path or some reorder release timeout)
can add frames to it.

Only one active rx handler worker [ieee80211_rx_handlers]
is needed. All other threads which have lost the race of
"runnning_rx_handler" can now simply "return", knowing that
the thread who had the "edge" will also take care of their
workload.

Signed-off-by: default avatarChristian Lamparter <chunkeey@googlemail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 1186488b

net/mac80211/ieee80211_i.h

+9 −0
Original line number Diff line number Diff line
@@ -761,6 +761,15 @@ struct ieee80211_local { 
	struct sk_buff_head skb_queue;

	struct sk_buff_head skb_queue_unreliable;



	/*

	 * Internal FIFO queue which is shared between multiple rx path

	 * stages. Its main task is to provide a serialization mechanism,

	 * so all rx handlers can enjoy having exclusive access to their

	 * private data structures.

	 */

	struct sk_buff_head rx_skb_queue;

	bool running_rx_handler;	/* protected by rx_skb_queue.lock */



	/* Station data */

	/*

	 * The mutex only protects the list and counter,

net/mac80211/main.c

+3 −0
Original line number Diff line number Diff line
@@ -569,6 +569,8 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len, 
	spin_lock_init(&local->filter_lock);

	spin_lock_init(&local->queue_stop_reason_lock);



	skb_queue_head_init(&local->rx_skb_queue);



	INIT_DELAYED_WORK(&local->scan_work, ieee80211_scan_work);



	ieee80211_work_init(local);
@@ -912,6 +914,7 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw) 
		wiphy_warn(local->hw.wiphy, "skb_queue not empty\n");

	skb_queue_purge(&local->skb_queue);

	skb_queue_purge(&local->skb_queue_unreliable);

	skb_queue_purge(&local->rx_skb_queue);



	destroy_workqueue(local->workqueue);

	wiphy_unregister(local->hw.wiphy);

net/mac80211/rx.c

+37 −43
Original line number Diff line number Diff line
@@ -533,9 +533,9 @@ static inline u16 seq_sub(u16 sq1, u16 sq2) 


static void ieee80211_release_reorder_frame(struct ieee80211_hw *hw,

					    struct tid_ampdu_rx *tid_agg_rx,

					    int index,

					    struct sk_buff_head *frames)

					    int index)

{

	struct ieee80211_local *local = hw_to_local(hw);

	struct sk_buff *skb = tid_agg_rx->reorder_buf[index];

	struct ieee80211_rx_status *status;
@@ -549,7 +549,7 @@ static void ieee80211_release_reorder_frame(struct ieee80211_hw *hw, 
	tid_agg_rx->reorder_buf[index] = NULL;

	status = IEEE80211_SKB_RXCB(skb);

	status->rx_flags |= IEEE80211_RX_DEFERRED_RELEASE;

	__skb_queue_tail(frames, skb);

	skb_queue_tail(&local->rx_skb_queue, skb);



no_frame:

	tid_agg_rx->head_seq_num = seq_inc(tid_agg_rx->head_seq_num);
@@ -557,8 +557,7 @@ static void ieee80211_release_reorder_frame(struct ieee80211_hw *hw, 


static void ieee80211_release_reorder_frames(struct ieee80211_hw *hw,

					     struct tid_ampdu_rx *tid_agg_rx,

					     u16 head_seq_num,

					     struct sk_buff_head *frames)

					     u16 head_seq_num)

{

	int index;
@@ -567,7 +566,7 @@ static void ieee80211_release_reorder_frames(struct ieee80211_hw *hw, 
	while (seq_less(tid_agg_rx->head_seq_num, head_seq_num)) {

		index = seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn) %

							tid_agg_rx->buf_size;

		ieee80211_release_reorder_frame(hw, tid_agg_rx, index, frames);

		ieee80211_release_reorder_frame(hw, tid_agg_rx, index);

	}

}
@@ -583,8 +582,7 @@ static void ieee80211_release_reorder_frames(struct ieee80211_hw *hw, 
#define HT_RX_REORDER_BUF_TIMEOUT (HZ / 10)



static void ieee80211_sta_reorder_release(struct ieee80211_hw *hw,

					  struct tid_ampdu_rx *tid_agg_rx,

					  struct sk_buff_head *frames)

					  struct tid_ampdu_rx *tid_agg_rx)

{

	int index, j;
@@ -615,8 +613,7 @@ static void ieee80211_sta_reorder_release(struct ieee80211_hw *hw, 
				wiphy_debug(hw->wiphy,

					    "release an RX reorder frame due to timeout on earlier frames\n");

#endif

			ieee80211_release_reorder_frame(hw, tid_agg_rx,

							j, frames);

			ieee80211_release_reorder_frame(hw, tid_agg_rx, j);



			/*

			 * Increment the head seq# also for the skipped slots.
@@ -626,7 +623,7 @@ static void ieee80211_sta_reorder_release(struct ieee80211_hw *hw, 
			skipped = 0;

		}

	} else while (tid_agg_rx->reorder_buf[index]) {

		ieee80211_release_reorder_frame(hw, tid_agg_rx, index, frames);

		ieee80211_release_reorder_frame(hw, tid_agg_rx, index);

		index =	seq_sub(tid_agg_rx->head_seq_num, tid_agg_rx->ssn) %

							tid_agg_rx->buf_size;

	}
@@ -682,8 +679,7 @@ static void ieee80211_sta_reorder_release(struct ieee80211_hw *hw, 
 */

static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw,

					     struct tid_ampdu_rx *tid_agg_rx,

					     struct sk_buff *skb,

					     struct sk_buff_head *frames)

					     struct sk_buff *skb)

{

	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;

	u16 sc = le16_to_cpu(hdr->seq_ctrl);
@@ -710,8 +706,7 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw, 
	if (!seq_less(mpdu_seq_num, head_seq_num + buf_size)) {

		head_seq_num = seq_inc(seq_sub(mpdu_seq_num, buf_size));

		/* release stored frames up to new head to stack */

		ieee80211_release_reorder_frames(hw, tid_agg_rx, head_seq_num,

						 frames);

		ieee80211_release_reorder_frames(hw, tid_agg_rx, head_seq_num);

	}



	/* Now the new frame is always in the range of the reordering buffer */
@@ -739,7 +734,7 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw, 
	tid_agg_rx->reorder_buf[index] = skb;

	tid_agg_rx->reorder_time[index] = jiffies;

	tid_agg_rx->stored_mpdu_num++;

	ieee80211_sta_reorder_release(hw, tid_agg_rx, frames);

	ieee80211_sta_reorder_release(hw, tid_agg_rx);



 out:

	spin_unlock(&tid_agg_rx->reorder_lock);
@@ -750,8 +745,7 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_hw *hw, 
 * Reorder MPDUs from A-MPDUs, keeping them on a buffer. Returns

 * true if the MPDU was buffered, false if it should be processed.

 */

static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx,

				       struct sk_buff_head *frames)

static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx)

{

	struct sk_buff *skb = rx->skb;

	struct ieee80211_local *local = rx->local;
@@ -806,11 +800,11 @@ static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx, 
	 * sure that we cannot get to it any more before doing

	 * anything with it.

	 */

	if (ieee80211_sta_manage_reorder_buf(hw, tid_agg_rx, skb, frames))

	if (ieee80211_sta_manage_reorder_buf(hw, tid_agg_rx, skb))

		return;



 dont_reorder:

	__skb_queue_tail(frames, skb);

	skb_queue_tail(&local->rx_skb_queue, skb);

}



static ieee80211_rx_result debug_noinline
@@ -1931,7 +1925,7 @@ ieee80211_rx_h_data(struct ieee80211_rx_data *rx) 
}



static ieee80211_rx_result debug_noinline

ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx, struct sk_buff_head *frames)

ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx)

{

	struct ieee80211_local *local = rx->local;

	struct ieee80211_hw *hw = &local->hw;
@@ -1971,8 +1965,7 @@ ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx, struct sk_buff_head *frames) 


		spin_lock(&tid_agg_rx->reorder_lock);

		/* release stored frames up to start of BAR */

		ieee80211_release_reorder_frames(hw, tid_agg_rx, start_seq_num,

						 frames);

		ieee80211_release_reorder_frames(hw, tid_agg_rx, start_seq_num);

		spin_unlock(&tid_agg_rx->reorder_lock);



		kfree_skb(skb);
@@ -2489,8 +2482,7 @@ static void ieee80211_rx_handlers_result(struct ieee80211_rx_data *rx, 
	}

}



static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx,

				  struct sk_buff_head *frames)

static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx)

{

	ieee80211_rx_result res = RX_DROP_MONITOR;

	struct sk_buff *skb;
@@ -2502,7 +2494,15 @@ static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx, 
			goto rxh_next;  \

	} while (0);



	while ((skb = __skb_dequeue(frames))) {

	spin_lock(&rx->local->rx_skb_queue.lock);

	if (rx->local->running_rx_handler)

		goto unlock;



	rx->local->running_rx_handler = true;



	while ((skb = __skb_dequeue(&rx->local->rx_skb_queue))) {

		spin_unlock(&rx->local->rx_skb_queue.lock);



		/*

		 * all the other fields are valid across frames

		 * that belong to an aMPDU since they are on the
@@ -2525,12 +2525,7 @@ static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx, 
			CALL_RXH(ieee80211_rx_h_mesh_fwding);

#endif

		CALL_RXH(ieee80211_rx_h_data)



		/* special treatment -- needs the queue */

		res = ieee80211_rx_h_ctrl(rx, frames);

		if (res != RX_CONTINUE)

			goto rxh_next;



		CALL_RXH(ieee80211_rx_h_ctrl);

		CALL_RXH(ieee80211_rx_h_mgmt_check)

		CALL_RXH(ieee80211_rx_h_action)

		CALL_RXH(ieee80211_rx_h_userspace_mgmt)
@@ -2539,18 +2534,20 @@ static void ieee80211_rx_handlers(struct ieee80211_rx_data *rx, 


 rxh_next:

		ieee80211_rx_handlers_result(rx, res);



		spin_lock(&rx->local->rx_skb_queue.lock);

#undef CALL_RXH

	}



	rx->local->running_rx_handler = false;



 unlock:

	spin_unlock(&rx->local->rx_skb_queue.lock);

}



static void ieee80211_invoke_rx_handlers(struct ieee80211_rx_data *rx)

{

	struct sk_buff_head reorder_release;

	ieee80211_rx_result res = RX_DROP_MONITOR;



	__skb_queue_head_init(&reorder_release);



#define CALL_RXH(rxh)			\

	do {				\

		res = rxh(rx);		\
@@ -2561,9 +2558,9 @@ static void ieee80211_invoke_rx_handlers(struct ieee80211_rx_data *rx) 
	CALL_RXH(ieee80211_rx_h_passive_scan)

	CALL_RXH(ieee80211_rx_h_check)



	ieee80211_rx_reorder_ampdu(rx, &reorder_release);

	ieee80211_rx_reorder_ampdu(rx);



	ieee80211_rx_handlers(rx, &reorder_release);

	ieee80211_rx_handlers(rx);

	return;



 rxh_next:
@@ -2578,7 +2575,6 @@ static void ieee80211_invoke_rx_handlers(struct ieee80211_rx_data *rx) 
 */

void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid)

{

	struct sk_buff_head frames;

	struct ieee80211_rx_data rx = {

		.sta = sta,

		.sdata = sta->sdata,
@@ -2591,13 +2587,11 @@ void ieee80211_release_reorder_timeout(struct sta_info *sta, int tid) 
	if (!tid_agg_rx)

		return;



	__skb_queue_head_init(&frames);



	spin_lock(&tid_agg_rx->reorder_lock);

	ieee80211_sta_reorder_release(&sta->local->hw, tid_agg_rx, &frames);

	ieee80211_sta_reorder_release(&sta->local->hw, tid_agg_rx);

	spin_unlock(&tid_agg_rx->reorder_lock);



	ieee80211_rx_handlers(&rx, &frames);

	ieee80211_rx_handlers(&rx);

}



/* main receive path */