[PATCH 5.10 62/83] gve: fix gve_get_stats()

Greg Kroah-Hartman
2021-10-11T13:57:19Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 2f57d4975fa027eabd35fdf23a49f8222ef3abf2 ]

gve_get_stats() can report wrong numbers if/when u64_stats_fetch_retry()
returns true.

What is needed here is to sample values in temporary variables,
and only use them after each loop is ended.

Fixes: f5cedc84a30d ("gve: Add transmit and receive support")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Catherine Sullivan <csully@google.com>
Cc: Sagi Shahar <sagis@google.com>
Cc: Jon Olson <jonolson@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Luigi Rizzo <lrizzo@google.com>
Cc: Jeroen de Borst <jeroendb@google.com>
Cc: Tao Liu <xliutaox@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/google/gve/gve_main.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 22b2c6a8d08f..b658bf9b5399 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -30,6 +30,7 @@ static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
{
struct gve_priv *priv = netdev_priv(dev);
unsigned int start;
+ u64 packets, bytes;
int ring;

if (priv->rx) {
@@ -37,10 +38,12 @@ static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
do {
start =
u64_stats_fetch_begin(&priv->rx[ring].statss);
- s->rx_packets += priv->rx[ring].rpackets;
- s->rx_bytes += priv->rx[ring].rbytes;
+ packets = priv->rx[ring].rpackets;
+ bytes = priv->rx[ring].rbytes;
} while (u64_stats_fetch_retry(&priv->rx[ring].statss,
start));
+ s->rx_packets += packets;
+ s->rx_bytes += bytes;
}
}
if (priv->tx) {
@@ -48,10 +51,12 @@ static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
do {
start =
u64_stats_fetch_begin(&priv->tx[ring].statss);
- s->tx_packets += priv->tx[ring].pkt_done;
- s->tx_bytes += priv->tx[ring].bytes_done;
+ packets = priv->tx[ring].pkt_done;
+ bytes = priv->tx[ring].bytes_done;
} while (u64_stats_fetch_retry(&priv->tx[ring].statss,
start));
+ s->tx_packets += packets;
+ s->tx_bytes += bytes;
}
}
}
--
2.33.0