[PATCH net-next] netdevsim: 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>
---
 drivers/net/netdevsim/netdevsim.h |  8 ++++----
 drivers/net/netdevsim/psp.c       | 18 ++++++++++--------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 46c67983c517..f767fc8a7505 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -109,10 +109,10 @@ struct netdevsim {
 	int rq_reset_mode;
 
 	struct {
-		u64 rx_packets;
-		u64 rx_bytes;
-		u64 tx_packets;
-		u64 tx_bytes;
+		u64_stats_t rx_packets;
+		u64_stats_t rx_bytes;
+		u64_stats_t tx_packets;
+		u64_stats_t tx_bytes;
 		struct u64_stats_sync syncp;
 		struct psp_dev *dev;
 		u32 spi;
diff --git a/drivers/net/netdevsim/psp.c b/drivers/net/netdevsim/psp.c
index 727da06101ca..0b4d717253b0 100644
--- a/drivers/net/netdevsim/psp.c
+++ b/drivers/net/netdevsim/psp.c
@@ -72,10 +72,12 @@ nsim_do_psp(struct sk_buff *skb, struct netdevsim *ns,
 		skb->decrypted = 1;
 
 		u64_stats_update_begin(&ns->psp.syncp);
-		ns->psp.tx_packets++;
-		ns->psp.rx_packets++;
-		ns->psp.tx_bytes += skb->len - skb_inner_transport_offset(skb);
-		ns->psp.rx_bytes += skb->len - skb_inner_transport_offset(skb);
+		u64_stats_inc(&ns->psp.tx_packets);
+		u64_stats_inc(&ns->psp.rx_packets);
+		u64_stats_add(&ns->psp.tx_bytes,
+			      skb->len - skb_inner_transport_offset(skb));
+		u64_stats_add(&ns->psp.rx_bytes,
+			      skb->len - skb_inner_transport_offset(skb));
 		u64_stats_update_end(&ns->psp.syncp);
 	} else {
 		struct ipv6hdr *ip6h __maybe_unused;
@@ -183,10 +185,10 @@ static void nsim_get_stats(struct psp_dev *psd, struct psp_dev_stats *stats)
 
 	do {
 		start = u64_stats_fetch_begin(&ns->psp.syncp);
-		stats->rx_bytes = ns->psp.rx_bytes;
-		stats->rx_packets = ns->psp.rx_packets;
-		stats->tx_bytes = ns->psp.tx_bytes;
-		stats->tx_packets = ns->psp.tx_packets;
+		stats->rx_bytes = u64_stats_read(&ns->psp.rx_bytes);
+		stats->rx_packets = u64_stats_read(&ns->psp.rx_packets);
+		stats->tx_bytes = u64_stats_read(&ns->psp.tx_bytes);
+		stats->tx_packets = u64_stats_read(&ns->psp.tx_packets);
 	} while (u64_stats_fetch_retry(&ns->psp.syncp, start));
 }
 
-- 
2.51.0