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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Vladimir Oltean <vladimir.oltean@nxp.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.19 252/365] net: mscc: ocelot: fix race between ndo_get_stats64 and ocelot_check_stats_work
Date:   Tue, 23 Aug 2022 10:02:33 +0200
Message-Id: <20220823080128.729548690@linuxfoundation.org>
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From: Vladimir Oltean <vladimir.oltean@nxp.com>

[ 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>
---
 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[],
-- 
2.35.1