[PATCH wireless-next] wifi: mac80211: use u64_stats_t with u64_stats_sync properly

[David Yang <mmyangfl@gmail.com>]

On 64bit arches, struct u64_stats_sync is empty and provides no help
against load/store tearing. Convert to u64_stats_t to ensure atomic
operations.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
 net/mac80211/rx.c       |  8 ++++----
 net/mac80211/sta_info.c | 22 +++++++++++++++++-----
 net/mac80211/sta_info.h |  4 ++--
 3 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index e0ccd9749853..577c505a5d10 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1880,7 +1880,7 @@ ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
 	link_sta->rx_stats.fragments++;
 
 	u64_stats_update_begin(&link_sta->rx_stats.syncp);
-	link_sta->rx_stats.bytes += rx->skb->len;
+	u64_stats_add(&link_sta->rx_stats.bytes, rx->skb->len);
 	u64_stats_update_end(&link_sta->rx_stats.syncp);
 
 	if (!(status->flag & RX_FLAG_NO_SIGNAL_VAL)) {
@@ -2777,7 +2777,7 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
 		 * frame, so count MSDUs.
 		 */
 		u64_stats_update_begin(&rx->link_sta->rx_stats.syncp);
-		rx->link_sta->rx_stats.msdu[rx->seqno_idx]++;
+		u64_stats_inc(&rx->link_sta->rx_stats.msdu[rx->seqno_idx]);
 		u64_stats_update_end(&rx->link_sta->rx_stats.syncp);
 	}
 
@@ -4868,8 +4868,8 @@ static void ieee80211_rx_8023(struct ieee80211_rx_data *rx,
 	 * frame, so count MSDUs.
 	 */
 	u64_stats_update_begin(&stats->syncp);
-	stats->msdu[rx->seqno_idx]++;
-	stats->bytes += orig_len;
+	u64_stats_inc(&stats->msdu[rx->seqno_idx]);
+	u64_stats_add(&stats->bytes, orig_len);
 	u64_stats_update_end(&stats->syncp);
 
 	if (fast_rx->internal_forward) {
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 1a995bc301b1..22e8561ad6fc 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -360,7 +360,9 @@ static void sta_accumulate_removed_link_stats(struct sta_info *sta, int link_id)
 	struct link_sta_info *link_sta = wiphy_dereference(sta->local->hw.wiphy,
 							   sta->link[link_id]);
 	struct ieee80211_link_data *link;
+	unsigned int start;
 	int ac, tid;
+	u64 value;
 	u32 thr;
 
 	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
@@ -369,8 +371,13 @@ static void sta_accumulate_removed_link_stats(struct sta_info *sta, int link_id)
 		sta->rem_link_stats.tx_bytes += link_sta->tx_stats.bytes[ac];
 	}
 
+	do {
+		start = u64_stats_fetch_begin(&link_sta->rx_stats.syncp);
+		value = u64_stats_read(&link_sta->rx_stats.bytes);
+	} while (u64_stats_fetch_retry(&link_sta->rx_stats.syncp, start));
+
 	sta->rem_link_stats.rx_packets += link_sta->rx_stats.packets;
-	sta->rem_link_stats.rx_bytes += link_sta->rx_stats.bytes;
+	sta->rem_link_stats.rx_bytes += value;
 	sta->rem_link_stats.tx_retries += link_sta->status_stats.retry_count;
 	sta->rem_link_stats.tx_failed += link_sta->status_stats.retry_failed;
 	sta->rem_link_stats.rx_dropped_misc += link_sta->rx_stats.dropped;
@@ -380,8 +387,13 @@ static void sta_accumulate_removed_link_stats(struct sta_info *sta, int link_id)
 		sta->rem_link_stats.expected_throughput += thr;
 
 	for (tid = 0; tid < IEEE80211_NUM_TIDS; tid++) {
-		sta->rem_link_stats.pertid_stats.rx_msdu +=
-			link_sta->rx_stats.msdu[tid];
+		do {
+			start = u64_stats_fetch_begin(&link_sta->rx_stats.syncp);
+			value = u64_stats_read(&link_sta->rx_stats.msdu[tid]);
+		} while (u64_stats_fetch_retry(&link_sta->rx_stats.syncp,
+					       start));
+
+		sta->rem_link_stats.pertid_stats.rx_msdu += value;
 		sta->rem_link_stats.pertid_stats.tx_msdu +=
 			link_sta->tx_stats.msdu[tid];
 		sta->rem_link_stats.pertid_stats.tx_msdu_retries +=
@@ -2578,7 +2590,7 @@ static inline u64 sta_get_tidstats_msdu(struct ieee80211_sta_rx_stats *rxstats,
 
 	do {
 		start = u64_stats_fetch_begin(&rxstats->syncp);
-		value = rxstats->msdu[tid];
+		value = u64_stats_read(&rxstats->msdu[tid]);
 	} while (u64_stats_fetch_retry(&rxstats->syncp, start));
 
 	return value;
@@ -2654,7 +2666,7 @@ static inline u64 sta_get_stats_bytes(struct ieee80211_sta_rx_stats *rxstats)
 
 	do {
 		start = u64_stats_fetch_begin(&rxstats->syncp);
-		value = rxstats->bytes;
+		value = u64_stats_read(&rxstats->bytes);
 	} while (u64_stats_fetch_retry(&rxstats->syncp, start));
 
 	return value;
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 5288d5286651..b1edf8ed102f 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -434,8 +434,8 @@ struct ieee80211_sta_rx_stats {
 	s8 chain_signal_last[IEEE80211_MAX_CHAINS];
 	u32 last_rate;
 	struct u64_stats_sync syncp;
-	u64 bytes;
-	u64 msdu[IEEE80211_NUM_TIDS + 1];
+	u64_stats_t bytes;
+	u64_stats_t msdu[IEEE80211_NUM_TIDS + 1];
 };
 
 /*
-- 
2.51.0