[PATCH net 5/8] net: mscc: ocelot: fix race between ndo_get_stats64 and ocelot_check_stats_work

Vladimir Oltean
2022-08-16T13:54:39Z

The 2 methods can run concurrently, and one will change the window of
counters (SYS_STAT_CFG_STAT_VIEW) that the other sees. The fix is
similar to what commit 7fbf6795d127 ("net: mscc: ocelot: fix mutex lock
error during ethtool stats read") has done for ethtool -S.

Fixes: a556c76adc05 ("net: mscc: Add initial Ocelot switch support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
drivers/net/ethernet/mscc/ocelot_net.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c
index 9d8cea16245e..6b9d37138844 100644
--- a/drivers/net/ethernet/mscc/ocelot_net.c
+++ b/drivers/net/ethernet/mscc/ocelot_net.c
@@ -726,6 +726,8 @@ static void ocelot_get_stats64(struct net_device *dev,
struct ocelot *ocelot = priv->port.ocelot;
int port = priv->port.index;

+ spin_lock(&ocelot->stats_lock);
+
/* Configure the port to read the stats from */
ocelot_write(ocelot, SYS_STAT_CFG_STAT_VIEW(port),
SYS_STAT_CFG);
@@ -758,6 +760,8 @@ static void ocelot_get_stats64(struct net_device *dev,
stats->tx_dropped = ocelot_read(ocelot, SYS_COUNT_TX_DROPS) +
ocelot_read(ocelot, SYS_COUNT_TX_AGING);
stats->collisions = ocelot_read(ocelot, SYS_COUNT_TX_COLLISION);
+
+ spin_unlock(&ocelot->stats_lock);
}

static int ocelot_port_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
--
2.34.1