net: mscc: ocelot: fix race between ndo_get_stats64 and ocelot_check_stats_work

[ Upstream commit 18d8e67df184081bc6ce6220a2dd965cfd3d7e6b ]

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>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c
index 9d8cea16245ef6445c77e32c44c038dc044e0217..6b9d371388441bf9cd2ec6f30f104b4474a26690 100644 (file)
--- 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[],