---

yaml
---
r: 203004
b: refs/heads/master
c: a87f736
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c1475ca99edcc7216ddc45838ab2c3281c14ba22
+refs/heads/master: a87f736d942c86255e3088c606f0e3eab6bbf784

trunk/net/mac80211/agg-rx.c

@@ -19,25 +19,36 @@
 #include "ieee80211_i.h"
 #include "driver-ops.h"
 
+static void ieee80211_free_tid_rx(struct rcu_head *h)
+{
+	struct tid_ampdu_rx *tid_rx =
+		container_of(h, struct tid_ampdu_rx, rcu_head);
+	int i;
+
+	for (i = 0; i < tid_rx->buf_size; i++)
+		dev_kfree_skb(tid_rx->reorder_buf[i]);
+	kfree(tid_rx->reorder_buf);
+	kfree(tid_rx->reorder_time);
+	kfree(tid_rx);
+}
+
 static void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 					    u16 initiator, u16 reason,
 					    bool from_timer)
 {
 	struct ieee80211_local *local = sta->local;
 	struct tid_ampdu_rx *tid_rx;
-	int i;
 
 	spin_lock_bh(&sta->lock);
 
-	/* check if TID is in operational state */
-	if (!sta->ampdu_mlme.tid_active_rx[tid]) {
+	tid_rx = sta->ampdu_mlme.tid_rx[tid];
+
+	if (!tid_rx) {
 		spin_unlock_bh(&sta->lock);
 		return;
 	}
 
-	sta->ampdu_mlme.tid_active_rx[tid] = false;
-
-	tid_rx = sta->ampdu_mlme.tid_rx[tid];
+	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], NULL);
 
 #ifdef CONFIG_MAC80211_HT_DEBUG
 	printk(KERN_DEBUG "Rx BA session stop requested for %pM tid %u\n",
@@ -54,26 +65,12 @@ static void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
 		ieee80211_send_delba(sta->sdata, sta->sta.addr,
 				     tid, 0, reason);
 
-	/* free the reordering buffer */
-	for (i = 0; i < tid_rx->buf_size; i++) {
-		if (tid_rx->reorder_buf[i]) {
-			/* release the reordered frames */
-			dev_kfree_skb(tid_rx->reorder_buf[i]);
-			tid_rx->stored_mpdu_num--;
-			tid_rx->reorder_buf[i] = NULL;
-		}
-	}
-
-	/* free resources */
-	kfree(tid_rx->reorder_buf);
-	kfree(tid_rx->reorder_time);
-	sta->ampdu_mlme.tid_rx[tid] = NULL;
-
 	spin_unlock_bh(&sta->lock);
 
 	if (!from_timer)
 		del_timer_sync(&tid_rx->session_timer);
-	kfree(tid_rx);
+
+	call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
 }
 
 void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
@@ -214,7 +211,7 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 	/* examine state machine */
 	spin_lock_bh(&sta->lock);
 
-	if (sta->ampdu_mlme.tid_active_rx[tid]) {
+	if (sta->ampdu_mlme.tid_rx[tid]) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_DEBUG "unexpected AddBA Req from "
@@ -225,24 +222,20 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 	}
 
 	/* prepare A-MPDU MLME for Rx aggregation */
-	sta->ampdu_mlme.tid_rx[tid] =
-			kmalloc(sizeof(struct tid_ampdu_rx), GFP_ATOMIC);
-	if (!sta->ampdu_mlme.tid_rx[tid]) {
+	tid_agg_rx = kmalloc(sizeof(struct tid_ampdu_rx), GFP_ATOMIC);
+	if (!tid_agg_rx) {
 #ifdef CONFIG_MAC80211_HT_DEBUG
 		if (net_ratelimit())
 			printk(KERN_ERR "allocate rx mlme to tid %d failed\n",
 					tid);
 #endif
 		goto end;
 	}
-	/* rx timer */
-	sta->ampdu_mlme.tid_rx[tid]->session_timer.function =
-				sta_rx_agg_session_timer_expired;
-	sta->ampdu_mlme.tid_rx[tid]->session_timer.data =
-				(unsigned long)&sta->timer_to_tid[tid];
-	init_timer(&sta->ampdu_mlme.tid_rx[tid]->session_timer);
 
-	tid_agg_rx = sta->ampdu_mlme.tid_rx[tid];
+	/* rx timer */
+	tid_agg_rx->session_timer.function = sta_rx_agg_session_timer_expired;
+	tid_agg_rx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid];
+	init_timer(&tid_agg_rx->session_timer);
 
 	/* prepare reordering buffer */
 	tid_agg_rx->reorder_buf =
@@ -257,8 +250,7 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 #endif
 		kfree(tid_agg_rx->reorder_buf);
 		kfree(tid_agg_rx->reorder_time);
-		kfree(sta->ampdu_mlme.tid_rx[tid]);
-		sta->ampdu_mlme.tid_rx[tid] = NULL;
+		kfree(tid_agg_rx);
 		goto end;
 	}
 
@@ -270,20 +262,22 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 
 	if (ret) {
 		kfree(tid_agg_rx->reorder_buf);
+		kfree(tid_agg_rx->reorder_time);
 		kfree(tid_agg_rx);
-		sta->ampdu_mlme.tid_rx[tid] = NULL;
 		goto end;
 	}
 
-	/* change state and send addba resp */
-	sta->ampdu_mlme.tid_active_rx[tid] = true;
+	/* update data */
 	tid_agg_rx->dialog_token = dialog_token;
 	tid_agg_rx->ssn = start_seq_num;
 	tid_agg_rx->head_seq_num = start_seq_num;
 	tid_agg_rx->buf_size = buf_size;
 	tid_agg_rx->timeout = timeout;
 	tid_agg_rx->stored_mpdu_num = 0;
 	status = WLAN_STATUS_SUCCESS;
+
+	/* activate it for RX */
+	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx);
 end:
 	spin_unlock_bh(&sta->lock);
 

trunk/net/mac80211/debugfs_sta.c

@@ -125,12 +125,12 @@ static ssize_t sta_agg_status_read(struct file *file, char __user *userbuf,
 	for (i = 0; i < STA_TID_NUM; i++) {
 		p += scnprintf(p, sizeof(buf) + buf - p, "%02d", i);
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t\t%x",
-				sta->ampdu_mlme.tid_active_rx[i]);
+				!!sta->ampdu_mlme.tid_rx[i]);
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.2x",
-				sta->ampdu_mlme.tid_active_rx[i] ?
+				sta->ampdu_mlme.tid_rx[i] ?
 				sta->ampdu_mlme.tid_rx[i]->dialog_token : 0);
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t%#.3x",
-				sta->ampdu_mlme.tid_active_rx[i] ?
+				sta->ampdu_mlme.tid_rx[i] ?
 				sta->ampdu_mlme.tid_rx[i]->ssn : 0);
 
 		p += scnprintf(p, sizeof(buf) + buf - p, "\t\t%x",

trunk/net/mac80211/rx.c

@@ -719,16 +719,13 @@ static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx,
 
 	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
 
-	spin_lock(&sta->lock);
-
-	if (!sta->ampdu_mlme.tid_active_rx[tid])
-		goto dont_reorder_unlock;
-
-	tid_agg_rx = sta->ampdu_mlme.tid_rx[tid];
+	tid_agg_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[tid]);
+	if (!tid_agg_rx)
+		goto dont_reorder;
 
 	/* qos null data frames are excluded */
 	if (unlikely(hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_NULLFUNC)))
-		goto dont_reorder_unlock;
+		goto dont_reorder;
 
 	/* new, potentially un-ordered, ampdu frame - process it */
 
@@ -740,20 +737,22 @@ static void ieee80211_rx_reorder_ampdu(struct ieee80211_rx_data *rx,
 	/* if this mpdu is fragmented - terminate rx aggregation session */
 	sc = le16_to_cpu(hdr->seq_ctrl);
 	if (sc & IEEE80211_SCTL_FRAG) {
-		spin_unlock(&sta->lock);
 		skb->pkt_type = IEEE80211_SDATA_QUEUE_TYPE_FRAME;
 		skb_queue_tail(&rx->sdata->skb_queue, skb);
 		ieee80211_queue_work(&local->hw, &rx->sdata->work);
 		return;
 	}
 
-	if (ieee80211_sta_manage_reorder_buf(hw, tid_agg_rx, skb, frames)) {
-		spin_unlock(&sta->lock);
+	/*
+	 * No locking needed -- we will only ever process one
+	 * RX packet at a time, and thus own tid_agg_rx. All
+	 * other code manipulating it needs to (and does) make
+	 * 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))
 		return;
-	}
 
- dont_reorder_unlock:
-	spin_unlock(&sta->lock);
  dont_reorder:
 	__skb_queue_tail(frames, skb);
 }
@@ -1830,13 +1829,11 @@ ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx, struct sk_buff_head *frames)
 				  &bar_data, sizeof(bar_data)))
 			return RX_DROP_MONITOR;
 
-		spin_lock(&rx->sta->lock);
 		tid = le16_to_cpu(bar_data.control) >> 12;
-		if (!rx->sta->ampdu_mlme.tid_active_rx[tid]) {
-			spin_unlock(&rx->sta->lock);
+
+		tid_agg_rx = rcu_dereference(rx->sta->ampdu_mlme.tid_rx[tid]);
+		if (!tid_agg_rx)
 			return RX_DROP_MONITOR;
-		}
-		tid_agg_rx = rx->sta->ampdu_mlme.tid_rx[tid];
 
 		start_seq_num = le16_to_cpu(bar_data.start_seq_num) >> 4;
 
@@ -1849,7 +1846,6 @@ ieee80211_rx_h_ctrl(struct ieee80211_rx_data *rx, struct sk_buff_head *frames)
 		ieee80211_release_reorder_frames(hw, tid_agg_rx, start_seq_num,
 						 frames);
 		kfree_skb(skb);
-		spin_unlock(&rx->sta->lock);
 		return RX_QUEUED;
 	}
 

trunk/net/mac80211/sta_info.h

@@ -102,8 +102,18 @@ struct tid_ampdu_tx {
  * @buf_size: buffer size for incoming A-MPDUs
  * @timeout: reset timer value (in TUs).
  * @dialog_token: dialog token for aggregation session
+ * @rcu_head: RCU head used for freeing this struct
+ *
+ * This structure is protected by RCU and the per-station
+ * spinlock. Assignments to the array holding it must hold
+ * the spinlock, only the RX path can access it under RCU
+ * lock-free. The RX path, since it is single-threaded,
+ * can even modify the structure without locking since the
+ * only other modifications to it are done when the struct
+ * can not yet or no longer be found by the RX path.
  */
 struct tid_ampdu_rx {
+	struct rcu_head rcu_head;
 	struct sk_buff **reorder_buf;
 	unsigned long *reorder_time;
 	struct timer_list session_timer;
@@ -118,16 +128,14 @@ struct tid_ampdu_rx {
 /**
  * struct sta_ampdu_mlme - STA aggregation information.
  *
- * @tid_active_rx: TID's state in Rx session state machine.
- * @tid_rx: aggregation info for Rx per TID
+ * @tid_rx: aggregation info for Rx per TID -- RCU protected
  * @tid_state_tx: TID's state in Tx session state machine.
  * @tid_tx: aggregation info for Tx per TID
  * @addba_req_num: number of times addBA request has been sent.
  * @dialog_token_allocator: dialog token enumerator for each new session;
  */
 struct sta_ampdu_mlme {
 	/* rx */
-	bool tid_active_rx[STA_TID_NUM];
 	struct tid_ampdu_rx *tid_rx[STA_TID_NUM];
 	/* tx */
 	u8 tid_state_tx[STA_TID_NUM];