net: use u64_stats_t in struct pcpu_lstats

In order to fix the data-race found by KCSAN, we
can use the new u64_stats_t type and its accessors instead
of plain u64 fields. This will still generate optimal code
for both 32 and 64 bit platforms.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/loopback.c

@@ -106,8 +106,8 @@ void dev_lstats_read(struct net_device *dev, u64 *packets, u64 *bytes)
 		lb_stats = per_cpu_ptr(dev->lstats, i);
 		do {
 			start = u64_stats_fetch_begin_irq(&lb_stats->syncp);
-			tpackets = lb_stats->packets;
-			tbytes = lb_stats->bytes;
+			tpackets = u64_stats_read(&lb_stats->packets);
+			tbytes = u64_stats_read(&lb_stats->bytes);
 		} while (u64_stats_fetch_retry_irq(&lb_stats->syncp, start));
 		*bytes   += tbytes;
 		*packets += tpackets;

include/linux/netdevice.h

@@ -2396,8 +2396,8 @@ struct pcpu_sw_netstats {
 } __aligned(4 * sizeof(u64));
 
 struct pcpu_lstats {
-	u64 packets;
-	u64 bytes;
+	u64_stats_t packets;
+	u64_stats_t bytes;
 	struct u64_stats_sync syncp;
 } __aligned(2 * sizeof(u64));
 
@@ -2408,8 +2408,8 @@ static inline void dev_lstats_add(struct net_device *dev, unsigned int len)
 	struct pcpu_lstats *lstats = this_cpu_ptr(dev->lstats);
 
 	u64_stats_update_begin(&lstats->syncp);
-	lstats->bytes += len;
-	lstats->packets++;
+	u64_stats_add(&lstats->bytes, len);
+	u64_stats_inc(&lstats->packets);
 	u64_stats_update_end(&lstats->syncp);
 }