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>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Hauke Mehrtens <hauke@hauke-m.de>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 169/355] net: dsa: lantiq_gswip: serialize access to the PCE table
Date:   Mon, 15 Nov 2021 18:01:33 +0100
Message-Id: <20211115165319.255917034@linuxfoundation.org>
In-Reply-To: <20211115165313.549179499@linuxfoundation.org>
References: <20211115165313.549179499@linuxfoundation.org>
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From: Vladimir Oltean <vladimir.oltean@nxp.com>

[ Upstream commit 49753a75b9a32de4c0393bb8d1e51ea223fda8e4 ]

Looking at the code, the GSWIP switch appears to hold bridging service
structures (VLANs, FDBs, forwarding rules) in PCE table entries.
Hardware access to the PCE table is non-atomic, and is comprised of
several register reads and writes.

These accesses are currently serialized by the rtnl_lock, but DSA is
changing its driver API and that lock will no longer be held when
calling ->port_fdb_add() and ->port_fdb_del().

So this driver needs to serialize the access to the PCE table using its
own locking scheme. This patch adds that.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/dsa/lantiq_gswip.c | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/lantiq_gswip.c b/drivers/net/dsa/lantiq_gswip.c
index 60e36f46f8abe..d612ef8648baa 100644
--- a/drivers/net/dsa/lantiq_gswip.c
+++ b/drivers/net/dsa/lantiq_gswip.c
@@ -274,6 +274,7 @@ struct gswip_priv {
 	int num_gphy_fw;
 	struct gswip_gphy_fw *gphy_fw;
 	u32 port_vlan_filter;
+	struct mutex pce_table_lock;
 };
 
 struct gswip_pce_table_entry {
@@ -521,10 +522,14 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 	u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSRD :
 					GSWIP_PCE_TBL_CTRL_OPMOD_ADRD;
 
+	mutex_lock(&priv->pce_table_lock);
+
 	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
 				     GSWIP_PCE_TBL_CTRL_BAS);
-	if (err)
+	if (err) {
+		mutex_unlock(&priv->pce_table_lock);
 		return err;
+	}
 
 	gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
 	gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
@@ -534,8 +539,10 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 
 	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
 				     GSWIP_PCE_TBL_CTRL_BAS);
-	if (err)
+	if (err) {
+		mutex_unlock(&priv->pce_table_lock);
 		return err;
+	}
 
 	for (i = 0; i < ARRAY_SIZE(tbl->key); i++)
 		tbl->key[i] = gswip_switch_r(priv, GSWIP_PCE_TBL_KEY(i));
@@ -551,6 +558,8 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 	tbl->valid = !!(crtl & GSWIP_PCE_TBL_CTRL_VLD);
 	tbl->gmap = (crtl & GSWIP_PCE_TBL_CTRL_GMAP_MASK) >> 7;
 
+	mutex_unlock(&priv->pce_table_lock);
+
 	return 0;
 }
 
@@ -563,10 +572,14 @@ static int gswip_pce_table_entry_write(struct gswip_priv *priv,
 	u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSWR :
 					GSWIP_PCE_TBL_CTRL_OPMOD_ADWR;
 
+	mutex_lock(&priv->pce_table_lock);
+
 	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
 				     GSWIP_PCE_TBL_CTRL_BAS);
-	if (err)
+	if (err) {
+		mutex_unlock(&priv->pce_table_lock);
 		return err;
+	}
 
 	gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
 	gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
@@ -598,8 +611,12 @@ static int gswip_pce_table_entry_write(struct gswip_priv *priv,
 	crtl |= GSWIP_PCE_TBL_CTRL_BAS;
 	gswip_switch_w(priv, crtl, GSWIP_PCE_TBL_CTRL);
 
-	return gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
-				      GSWIP_PCE_TBL_CTRL_BAS);
+	err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
+				     GSWIP_PCE_TBL_CTRL_BAS);
+
+	mutex_unlock(&priv->pce_table_lock);
+
+	return err;
 }
 
 /* Add the LAN port into a bridge with the CPU port by
@@ -2020,6 +2037,7 @@ static int gswip_probe(struct platform_device *pdev)
 	priv->ds->priv = priv;
 	priv->ds->ops = &gswip_switch_ops;
 	priv->dev = dev;
+	mutex_init(&priv->pce_table_lock);
 	version = gswip_switch_r(priv, GSWIP_VERSION);
 
 	/* bring up the mdio bus */
-- 
2.33.0