mac80211: fix Rx reordering with RX_FLAG_AMSDU_MORE

Some drivers (e.g. ath10k) report A-MSDU subframes
individually with identical seqno. The A-MPDU Rx
reorder code did not account for that which made
it practically unusable with drivers using
RX_FLAG_AMSDU_MORE because it would end up
dropping a lot of frames resulting in confusion in
upper network transport layers.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 62 insertions, 24 deletions

diff --git a/net/mac80211/agg-rx.c b/net/mac80211/agg-rx.c
index 31bf2586fb84..d38c49b644cd 100644
--- a/net/mac80211/agg-rx.c
+++ b/net/mac80211/agg-rx.c
@@ -52,7 +52,7 @@ static void ieee80211_free_tid_rx(struct rcu_head *h)
         del_timer_sync(&tid_rx->reorder_timer);
 
         for (i = 0; i < tid_rx->buf_size; i++)
-                dev_kfree_skb(tid_rx->reorder_buf[i]);
+                __skb_queue_purge(&tid_rx->reorder_buf[i]);
         kfree(tid_rx->reorder_buf);
         kfree(tid_rx->reorder_time);
         kfree(tid_rx);
@@ -232,7 +232,7 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
         struct tid_ampdu_rx *tid_agg_rx;
         u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num, status;
         u8 dialog_token;
-        int ret = -EOPNOTSUPP;
+        int i, ret = -EOPNOTSUPP;
 
         /* extract session parameters from addba request frame */
         dialog_token = mgmt->u.action.u.addba_req.dialog_token;
@@ -308,7 +308,7 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 
         /* prepare reordering buffer */
         tid_agg_rx->reorder_buf =
-                kcalloc(buf_size, sizeof(struct sk_buff *), GFP_KERNEL);
+                kcalloc(buf_size, sizeof(struct sk_buff_head), GFP_KERNEL);
         tid_agg_rx->reorder_time =
                 kcalloc(buf_size, sizeof(unsigned long), GFP_KERNEL);
         if (!tid_agg_rx->reorder_buf || !tid_agg_rx->reorder_time) {
@@ -318,6 +318,9 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
                 goto end;
         }
 
+        for (i = 0; i < buf_size; i++)
+                __skb_queue_head_init(&tid_agg_rx->reorder_buf[i]);
+
         ret = drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_START,
                                &sta->sta, tid, &start_seq_num, 0);
         ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d\n",
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 49731dd044bb..c504e99a5404 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1729,6 +1729,21 @@ static inline void ieee802_11_parse_elems(const u8 *start, size_t len,
         ieee802_11_parse_elems_crc(start, len, action, elems, 0, 0);
 }
 
+static inline bool ieee80211_rx_reorder_ready(struct sk_buff_head *frames)
+{
+        struct sk_buff *tail = skb_peek_tail(frames);
+        struct ieee80211_rx_status *status;
+
+        if (!tail)
+                return false;
+
+        status = IEEE80211_SKB_RXCB(tail);
+        if (status->flag & RX_FLAG_AMSDU_MORE)
+                return false;
+
+        return true;
+}
+
 void ieee80211_dynamic_ps_enable_work(struct work_struct *work);
 void ieee80211_dynamic_ps_disable_work(struct work_struct *work);
 void ieee80211_dynamic_ps_timer(unsigned long data);
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 5a786d489f7e..bd2c9b22c945 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -688,20 +688,27 @@ static void ieee80211_release_reorder_frame(struct ieee80211_sub_if_data *sdata,
                                             int index,
                                             struct sk_buff_head *frames)
 {
-        struct sk_buff *skb = tid_agg_rx->reorder_buf[index];
+        struct sk_buff_head *skb_list = &tid_agg_rx->reorder_buf[index];
+        struct sk_buff *skb;
         struct ieee80211_rx_status *status;
 
         lockdep_assert_held(&tid_agg_rx->reorder_lock);
 
-        if (!skb)
+        if (skb_queue_empty(skb_list))
                 goto no_frame;
 
-        /* release the frame from the reorder ring buffer */
+        if (!ieee80211_rx_reorder_ready(skb_list)) {
+                __skb_queue_purge(skb_list);
+                goto no_frame;
+        }
+
+        /* release frames from the reorder ring buffer */
         tid_agg_rx->stored_mpdu_num--;
-        tid_agg_rx->reorder_buf[index] = NULL;
-        status = IEEE80211_SKB_RXCB(skb);
-        status->rx_flags |= IEEE80211_RX_DEFERRED_RELEASE;
-        __skb_queue_tail(frames, skb);
+        while ((skb = __skb_dequeue(skb_list))) {
+                status = IEEE80211_SKB_RXCB(skb);
+                status->rx_flags |= IEEE80211_RX_DEFERRED_RELEASE;
+                __skb_queue_tail(frames, skb);
+        }
 
 no_frame:
         tid_agg_rx->head_seq_num = ieee80211_sn_inc(tid_agg_rx->head_seq_num);
@@ -738,13 +745,13 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
                                           struct tid_ampdu_rx *tid_agg_rx,
                                           struct sk_buff_head *frames)
 {
-        int index, j;
+        int index, i, j;
 
         lockdep_assert_held(&tid_agg_rx->reorder_lock);
 
         /* release the buffer until next missing frame */
         index = tid_agg_rx->head_seq_num % tid_agg_rx->buf_size;
-        if (!tid_agg_rx->reorder_buf[index] &&
+        if (!ieee80211_rx_reorder_ready(&tid_agg_rx->reorder_buf[index]) &&
             tid_agg_rx->stored_mpdu_num) {
                 /*
                  * No buffers ready to be released, but check whether any
@@ -753,7 +760,8 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
                 int skipped = 1;
                 for (j = (index + 1) % tid_agg_rx->buf_size; j != index;
                      j = (j + 1) % tid_agg_rx->buf_size) {
-                        if (!tid_agg_rx->reorder_buf[j]) {
+                        if (!ieee80211_rx_reorder_ready(
+                                        &tid_agg_rx->reorder_buf[j])) {
                                 skipped++;
                                 continue;
                         }
@@ -762,6 +770,11 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
                                         HT_RX_REORDER_BUF_TIMEOUT))
                                 goto set_release_timer;
 
+                        /* don't leave incomplete A-MSDUs around */
+                        for (i = (index + 1) % tid_agg_rx->buf_size; i != j;
+                             i = (i + 1) % tid_agg_rx->buf_size)
+                                __skb_queue_purge(&tid_agg_rx->reorder_buf[i]);
+
                         ht_dbg_ratelimited(sdata,
                                            "release an RX reorder frame due to timeout on earlier frames\n");
                         ieee80211_release_reorder_frame(sdata, tid_agg_rx, j,
@@ -775,7 +788,8 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
                                  skipped) & IEEE80211_SN_MASK;
                         skipped = 0;
                 }
-        } else while (tid_agg_rx->reorder_buf[index]) {
+        } else while (ieee80211_rx_reorder_ready(
+                                &tid_agg_rx->reorder_buf[index])) {
                 ieee80211_release_reorder_frame(sdata, tid_agg_rx, index,
                                                 frames);
                 index = tid_agg_rx->head_seq_num % tid_agg_rx->buf_size;
@@ -786,7 +800,8 @@ static void ieee80211_sta_reorder_release(struct ieee80211_sub_if_data *sdata,
 
                 for (; j != (index - 1) % tid_agg_rx->buf_size;
                      j = (j + 1) % tid_agg_rx->buf_size) {
-                        if (tid_agg_rx->reorder_buf[j])
+                        if (ieee80211_rx_reorder_ready(
+                                        &tid_agg_rx->reorder_buf[j]))
                                 break;
                 }
 
@@ -811,6 +826,7 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_sub_if_data *sdata
                                              struct sk_buff_head *frames)
 {
         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+        struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
         u16 sc = le16_to_cpu(hdr->seq_ctrl);
         u16 mpdu_seq_num = (sc & IEEE80211_SCTL_SEQ) >> 4;
         u16 head_seq_num, buf_size;
@@ -845,7 +861,7 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_sub_if_data *sdata
         index = mpdu_seq_num % tid_agg_rx->buf_size;
 
         /* check if we already stored this frame */
-        if (tid_agg_rx->reorder_buf[index]) {
+        if (ieee80211_rx_reorder_ready(&tid_agg_rx->reorder_buf[index])) {
                 dev_kfree_skb(skb);
                 goto out;
         }
@@ -858,17 +874,20 @@ static bool ieee80211_sta_manage_reorder_buf(struct ieee80211_sub_if_data *sdata
          */
         if (mpdu_seq_num == tid_agg_rx->head_seq_num &&
             tid_agg_rx->stored_mpdu_num == 0) {
-                tid_agg_rx->head_seq_num =
-                        ieee80211_sn_inc(tid_agg_rx->head_seq_num);
+                if (!(status->flag & RX_FLAG_AMSDU_MORE))
+                        tid_agg_rx->head_seq_num =
+                                ieee80211_sn_inc(tid_agg_rx->head_seq_num);
                 ret = false;
                 goto out;
         }
 
         /* put the frame in the reordering buffer */
-        tid_agg_rx->reorder_buf[index] = skb;
-        tid_agg_rx->reorder_time[index] = jiffies;
-        tid_agg_rx->stored_mpdu_num++;
-        ieee80211_sta_reorder_release(sdata, tid_agg_rx, frames);
+        __skb_queue_tail(&tid_agg_rx->reorder_buf[index], skb);
+        if (!(status->flag & RX_FLAG_AMSDU_MORE)) {
+                tid_agg_rx->reorder_time[index] = jiffies;
+                tid_agg_rx->stored_mpdu_num++;
+                ieee80211_sta_reorder_release(sdata, tid_agg_rx, frames);
+        }
 
  out:
         spin_unlock(&tid_agg_rx->reorder_lock);
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index e37f00969526..d411bcc8ef08 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -155,7 +155,8 @@ struct tid_ampdu_tx {
 /**
  * struct tid_ampdu_rx - TID aggregation information (Rx).
  *
- * @reorder_buf: buffer to reorder incoming aggregated MPDUs
+ * @reorder_buf: buffer to reorder incoming aggregated MPDUs. An MPDU may be an
+ *      A-MSDU with individually reported subframes.
  * @reorder_time: jiffies when skb was added
  * @session_timer: check if peer keeps Tx-ing on the TID (by timeout value)
  * @reorder_timer: releases expired frames from the reorder buffer.
@@ -180,7 +181,7 @@ struct tid_ampdu_tx {
 struct tid_ampdu_rx {
         struct rcu_head rcu_head;
         spinlock_t reorder_lock;
-        struct sk_buff **reorder_buf;
+        struct sk_buff_head *reorder_buf;
         unsigned long *reorder_time;
         struct timer_list session_timer;
         struct timer_list reorder_timer;