iwlwifi: use consistent table for tx data collect

When collecting tx data for non-aggregation packets in rate scaling, if
the tx data matches "other table", it still uses current table to update
the stats and calculate average throughput in function rs_collect_tx_data().
This can mess up the rate scaling data structure and cause a kernel panic
in a BUG_ON statement in rs_rate_scale_perform().

To fix this bug, we pass table pointer instead of window pointer (pointed
to by table pointer) to function rs_collect_tx_data() so that the table
being used is consistent.

Signed-off-by: Shanyu Zhao <[e-mail]>
Signed-off-by: Henry Zhang <[e-mail]>
Signed-off-by: Reinette Chatre <[e-mail]>

drivers/net/wireless/iwlwifi/iwl-agn-rs.c

···
 	       !!(rate_n_flags & RATE_MCS_ANT_C_MSK);
 }
 
+/*
+ * Static function to get the expected throughput from an iwl_scale_tbl_info
+ * that wraps a NULL pointer check
+ */
+static s32 get_expected_tpt(struct iwl_scale_tbl_info *tbl, int rs_index)
+{
+	if (tbl->expected_tpt)
+		return tbl->expected_tpt[rs_index];
+	return 0;
+}
+
 /**
  * rs_collect_tx_data - Update the success/failure sliding window
  *
···
  * at this rate.  window->data contains the bitmask of successful
  * packets.
  */
-static int rs_collect_tx_data(struct iwl_rate_scale_data *windows,
-			      int scale_index, s32 tpt, int attempts,
-			      int successes)
+static int rs_collect_tx_data(struct iwl_scale_tbl_info *tbl,
+			      int scale_index, int attempts, int successes)
 {
 	struct iwl_rate_scale_data *window = NULL;
 	static const u64 mask = (((u64)1) << (IWL_RATE_MAX_WINDOW - 1));
-	s32 fail_count;
+	s32 fail_count, tpt;
 
 	if (scale_index < 0 || scale_index >= IWL_RATE_COUNT)
 		return -EINVAL;
 
 	/* Select window for current tx bit rate */
-	window = &(windows[scale_index]);
+	window = &(tbl->win[scale_index]);
+
+	/* Get expected throughput */
+	tpt = get_expected_tpt(tbl, scale_index);
 
 	/*
 	 * Keep track of only the latest 62 tx frame attempts in this rate's
···
 	return (a->lq_type == b->lq_type) && (a->ant_type == b->ant_type) &&
 		(a->is_SGI == b->is_SGI);
 }
-/*
- * Static function to get the expected throughput from an iwl_scale_tbl_info
- * that wraps a NULL pointer check
- */
-static s32 get_expected_tpt(struct iwl_scale_tbl_info *tbl, int rs_index)
-{
-	if (tbl->expected_tpt)
-		return tbl->expected_tpt[rs_index];
-	return 0;
-}
 
 /*
  * mac80211 sends us Tx status
···
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	struct iwl_priv *priv = (struct iwl_priv *)priv_r;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-	struct iwl_rate_scale_data *window = NULL;
 	enum mac80211_rate_control_flags mac_flags;
 	u32 tx_rate;
 	struct iwl_scale_tbl_info tbl_type;
-	struct iwl_scale_tbl_info *curr_tbl, *other_tbl;
-	s32 tpt = 0;
+	struct iwl_scale_tbl_info *curr_tbl, *other_tbl, *tmp_tbl;
 
 	IWL_DEBUG_RATE_LIMIT(priv, "get frame ack response, update rate scale window\n");
 
···
 		IWL_DEBUG_RATE(priv, "Neither active nor search matches tx rate\n");
 		return;
 	}
-	window = (struct iwl_rate_scale_data *)&(curr_tbl->win[0]);
 
 	/*
 	 * Updating the frame history depends on whether packets were
···
 		tx_rate = le32_to_cpu(table->rs_table[0].rate_n_flags);
 		rs_get_tbl_info_from_mcs(tx_rate, priv->band, &tbl_type,
 				&rs_index);
-		tpt = get_expected_tpt(curr_tbl, rs_index);
-		rs_collect_tx_data(window, rs_index, tpt,
+		rs_collect_tx_data(curr_tbl, rs_index,
 				   info->status.ampdu_ack_len,
 				   info->status.ampdu_ack_map);
 
···
 			 * table as active/search.
 			 */
 			if (table_type_matches(&tbl_type, curr_tbl))
-				tpt = get_expected_tpt(curr_tbl, rs_index);
+				tmp_tbl = curr_tbl;
 			else if (table_type_matches(&tbl_type, other_tbl))
-				tpt = get_expected_tpt(other_tbl, rs_index);
+				tmp_tbl = other_tbl;
 			else
 				continue;
-
-			/* Constants mean 1 transmission, 0 successes */
-			if (i < retries)
-				rs_collect_tx_data(window, rs_index, tpt, 1,
-						0);
-			else
-				rs_collect_tx_data(window, rs_index, tpt, 1,
-						legacy_success);
+			rs_collect_tx_data(tmp_tbl, rs_index, 1,
+					   i < retries ? 0 : legacy_success);
 		}
 
 		/* Update success/fail counts if not searching for new mode */