From ec034b208dc8aa5dc73ec46c3f27e34c5efbf113 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 13 May 2011 13:35:40 +0200 Subject: mac80211: fix TX a-MPDU locking During my quest to make mac80211 not have any RCU warnings from sparse, I came across the a-MPDU code again and it wasn't quite clear why it isn't racy. So instead of assigning the tid_tx array with just the spinlock held in ieee80211_start_tx_ba_session use a separate temporary array protected only by the spinlock and protect all assignments to the "live" array by both the spinlock and the mutex so that other code is easily verified to be correct. Due to pointer assignment atomicity I don't think this is a real issue, but I'm not sure, especially on Alpha the current code might be problematic. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/agg-tx.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'net/mac80211/agg-tx.c') diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c index 63d852c..f614ee6 100644 --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -136,6 +136,14 @@ void ieee80211_send_bar(struct ieee80211_sub_if_data *sdata, u8 *ra, u16 tid, u1 ieee80211_tx_skb(sdata, skb); } +void ieee80211_assign_tid_tx(struct sta_info *sta, int tid, + struct tid_ampdu_tx *tid_tx) +{ + lockdep_assert_held(&sta->ampdu_mlme.mtx); + lockdep_assert_held(&sta->lock); + rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], tid_tx); +} + static void kfree_tid_tx(struct rcu_head *rcu_head) { struct tid_ampdu_tx *tid_tx = @@ -161,7 +169,7 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid, if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) { /* not even started yet! */ - rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL); + ieee80211_assign_tid_tx(sta, tid, NULL); spin_unlock_bh(&sta->lock); call_rcu(&tid_tx->rcu_head, kfree_tid_tx); return 0; @@ -318,7 +326,7 @@ void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid) " tid %d\n", tid); #endif spin_lock_bh(&sta->lock); - rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL); + ieee80211_assign_tid_tx(sta, tid, NULL); spin_unlock_bh(&sta->lock); ieee80211_wake_queue_agg(local, tid); @@ -398,7 +406,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid, tid_tx = sta->ampdu_mlme.tid_tx[tid]; /* check if the TID is not in aggregation flow already */ - if (tid_tx) { + if (tid_tx || sta->ampdu_mlme.tid_start_tx[tid]) { #ifdef CONFIG_MAC80211_HT_DEBUG printk(KERN_DEBUG "BA request denied - session is not " "idle on tid %u\n", tid); @@ -433,8 +441,11 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid, sta->ampdu_mlme.dialog_token_allocator++; tid_tx->dialog_token = sta->ampdu_mlme.dialog_token_allocator; - /* finally, assign it to the array */ - rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], tid_tx); + /* + * Finally, assign it to the start array; the work item will + * collect it and move it to the normal array. + */ + sta->ampdu_mlme.tid_start_tx[tid] = tid_tx; ieee80211_queue_work(&local->hw, &sta->ampdu_mlme.work); @@ -697,7 +708,7 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u8 tid) ieee80211_agg_splice_packets(local, tid_tx, tid); /* future packets must not find the tid_tx struct any more */ - rcu_assign_pointer(sta->ampdu_mlme.tid_tx[tid], NULL); + ieee80211_assign_tid_tx(sta, tid, NULL); ieee80211_agg_splice_finish(local, tid); -- cgit v1.1 From 40b275b69ee660274b77fb612b0db31fd282fc3f Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Fri, 13 May 2011 14:15:49 +0200 Subject: mac80211: sparse RCU annotations This adds sparse RCU annotations to most of mac80211, only the mesh code remains to be done. Due the the previous patches, the annotations are pretty simple. The only thing that this actually changes is removing the RCU usage of key->sta in debugfs since this pointer isn't actually an RCU-managed pointer (it only has a single assignment done before the key even goes live). As that is otherwise harmless, I decided to make it part of this patch. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/agg-tx.c | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-) (limited to 'net/mac80211/agg-tx.c') diff --git a/net/mac80211/agg-tx.c b/net/mac80211/agg-tx.c index f614ee6..cd5125f 100644 --- a/net/mac80211/agg-tx.c +++ b/net/mac80211/agg-tx.c @@ -157,16 +157,19 @@ int ___ieee80211_stop_tx_ba_session(struct sta_info *sta, u16 tid, bool tx) { struct ieee80211_local *local = sta->local; - struct tid_ampdu_tx *tid_tx = sta->ampdu_mlme.tid_tx[tid]; + struct tid_ampdu_tx *tid_tx; int ret; lockdep_assert_held(&sta->ampdu_mlme.mtx); - if (!tid_tx) - return -ENOENT; - spin_lock_bh(&sta->lock); + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); + if (!tid_tx) { + spin_unlock_bh(&sta->lock); + return -ENOENT; + } + if (test_bit(HT_AGG_STATE_WANT_START, &tid_tx->state)) { /* not even started yet! */ ieee80211_assign_tid_tx(sta, tid, NULL); @@ -291,13 +294,13 @@ ieee80211_wake_queue_agg(struct ieee80211_local *local, int tid) void ieee80211_tx_ba_session_handle_start(struct sta_info *sta, int tid) { - struct tid_ampdu_tx *tid_tx = sta->ampdu_mlme.tid_tx[tid]; + struct tid_ampdu_tx *tid_tx; struct ieee80211_local *local = sta->local; struct ieee80211_sub_if_data *sdata = sta->sdata; u16 start_seq_num; int ret; - lockdep_assert_held(&sta->ampdu_mlme.mtx); + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); /* * While we're asking the driver about the aggregation, @@ -404,7 +407,7 @@ int ieee80211_start_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid, goto err_unlock_sta; } - tid_tx = sta->ampdu_mlme.tid_tx[tid]; + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); /* check if the TID is not in aggregation flow already */ if (tid_tx || sta->ampdu_mlme.tid_start_tx[tid]) { #ifdef CONFIG_MAC80211_HT_DEBUG @@ -491,16 +494,19 @@ ieee80211_agg_splice_finish(struct ieee80211_local *local, u16 tid) static void ieee80211_agg_tx_operational(struct ieee80211_local *local, struct sta_info *sta, u16 tid) { + struct tid_ampdu_tx *tid_tx; + lockdep_assert_held(&sta->ampdu_mlme.mtx); + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); + #ifdef CONFIG_MAC80211_HT_DEBUG printk(KERN_DEBUG "Aggregation is on for tid %d\n", tid); #endif drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_TX_OPERATIONAL, - &sta->sta, tid, NULL, - sta->ampdu_mlme.tid_tx[tid]->buf_size); + &sta->sta, tid, NULL, tid_tx->buf_size); /* * synchronize with TX path, while splicing the TX path @@ -508,13 +514,13 @@ static void ieee80211_agg_tx_operational(struct ieee80211_local *local, */ spin_lock_bh(&sta->lock); - ieee80211_agg_splice_packets(local, sta->ampdu_mlme.tid_tx[tid], tid); + ieee80211_agg_splice_packets(local, tid_tx, tid); /* * Now mark as operational. This will be visible * in the TX path, and lets it go lock-free in * the common case. */ - set_bit(HT_AGG_STATE_OPERATIONAL, &sta->ampdu_mlme.tid_tx[tid]->state); + set_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state); ieee80211_agg_splice_finish(local, tid); spin_unlock_bh(&sta->lock); @@ -548,7 +554,7 @@ void ieee80211_start_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u16 tid) } mutex_lock(&sta->ampdu_mlme.mtx); - tid_tx = sta->ampdu_mlme.tid_tx[tid]; + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); if (WARN_ON(!tid_tx)) { #ifdef CONFIG_MAC80211_HT_DEBUG @@ -626,7 +632,7 @@ int ieee80211_stop_tx_ba_session(struct ieee80211_sta *pubsta, u16 tid) return -EINVAL; spin_lock_bh(&sta->lock); - tid_tx = sta->ampdu_mlme.tid_tx[tid]; + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); if (!tid_tx) { ret = -ENOENT; @@ -682,7 +688,7 @@ void ieee80211_stop_tx_ba_cb(struct ieee80211_vif *vif, u8 *ra, u8 tid) mutex_lock(&sta->ampdu_mlme.mtx); spin_lock_bh(&sta->lock); - tid_tx = sta->ampdu_mlme.tid_tx[tid]; + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); if (!tid_tx || !test_bit(HT_AGG_STATE_STOPPING, &tid_tx->state)) { #ifdef CONFIG_MAC80211_HT_DEBUG @@ -763,7 +769,7 @@ void ieee80211_process_addba_resp(struct ieee80211_local *local, mutex_lock(&sta->ampdu_mlme.mtx); - tid_tx = sta->ampdu_mlme.tid_tx[tid]; + tid_tx = rcu_dereference_protected_tid_tx(sta, tid); if (!tid_tx) goto out; -- cgit v1.1