[PATCH v5 net-next 05/10] net: dsa: b53: serialize access to the ARL table

From: Vladimir Oltean <vladimir.oltean@nxp.com>
To: netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Vivien Didelot" <vivien.didelot@gmail.com>,
	"Vladimir Oltean" <olteanv@gmail.com>,
	UNGLinuxDriver@microchip.com, "DENG Qingfang" <dqfext@gmail.com>,
	"Kurt Kanzenbach" <kurt@linutronix.de>,
	"Hauke Mehrtens" <hauke@hauke-m.de>,
	"Woojung Huh" <woojung.huh@microchip.com>,
	"Sean Wang" <sean.wang@mediatek.com>,
	"Landen Chao" <Landen.Chao@mediatek.com>,
	"Alexandre Belloni" <alexandre.belloni@bootlin.com>,
	"George McCollister" <george.mccollister@gmail.com>,
	"John Crispin" <john@phrozen.org>,
	"Aleksander Jan Bajkowski" <olek2@wp.pl>,
	"Egil Hjelmeland" <privat@egil-hjelmeland.no>,
	"Oleksij Rempel" <o.rempel@pengutronix.de>,
	"Prasanna Vengateshan" <prasanna.vengateshan@microchip.com>,
	"Ansuel Smith" <ansuelsmth@gmail.com>,
	"Alvin Šipraga" <alsi@bang-olufsen.dk>,
	"Claudiu Manoil" <claudiu.manoil@nxp.com>
Subject: [PATCH v5 net-next 05/10] net: dsa: b53: serialize access to the ARL table
Date: Sun, 24 Oct 2021 20:17:52 +0300	[thread overview]
Message-ID: <20211024171757.3753288-6-vladimir.oltean@nxp.com> (raw)
In-Reply-To: <20211024171757.3753288-1-vladimir.oltean@nxp.com>

The b53 driver performs non-atomic transactions to the ARL table when
adding, deleting and reading FDB and MDB entries.

Traditionally these were all serialized by the rtnl_lock(), but now it
is possible that DSA calls ->port_fdb_add and ->port_fdb_del without
holding that lock.

So the driver must have its own serialization logic. Add a mutex and
hold it from all entry points (->port_fdb_{add,del,dump},
->port_mdb_{add,del}).

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
---
v2->v3: unlock arl_mutex centrally in b53_fdb_dump
v3->v4: use __must_hold
v4->v5: revert changes made in v4

 drivers/net/dsa/b53/b53_common.c | 36 +++++++++++++++++++++++++-------
 drivers/net/dsa/b53/b53_priv.h   |  1 +
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index 06279ba64cc8..651ac72eed7f 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -1544,7 +1544,7 @@ int b53_vlan_del(struct dsa_switch *ds, int port,
 }
 EXPORT_SYMBOL(b53_vlan_del);
 
-/* Address Resolution Logic routines */
+/* Address Resolution Logic routines. Caller must hold &dev->arl_mutex. */
 static int b53_arl_op_wait(struct b53_device *dev)
 {
 	unsigned int timeout = 10;
@@ -1709,6 +1709,7 @@ int b53_fdb_add(struct dsa_switch *ds, int port,
 		const unsigned char *addr, u16 vid)
 {
 	struct b53_device *priv = ds->priv;
+	int ret;
 
 	/* 5325 and 5365 require some more massaging, but could
 	 * be supported eventually
@@ -1716,7 +1717,11 @@ int b53_fdb_add(struct dsa_switch *ds, int port,
 	if (is5325(priv) || is5365(priv))
 		return -EOPNOTSUPP;
 
-	return b53_arl_op(priv, 0, port, addr, vid, true);
+	mutex_lock(&priv->arl_mutex);
+	ret = b53_arl_op(priv, 0, port, addr, vid, true);
+	mutex_unlock(&priv->arl_mutex);
+
+	return ret;
 }
 EXPORT_SYMBOL(b53_fdb_add);
 
@@ -1724,8 +1729,13 @@ int b53_fdb_del(struct dsa_switch *ds, int port,
 		const unsigned char *addr, u16 vid)
 {
 	struct b53_device *priv = ds->priv;
+	int ret;
 
-	return b53_arl_op(priv, 0, port, addr, vid, false);
+	mutex_lock(&priv->arl_mutex);
+	ret = b53_arl_op(priv, 0, port, addr, vid, false);
+	mutex_unlock(&priv->arl_mutex);
+
+	return ret;
 }
 EXPORT_SYMBOL(b53_fdb_del);
 
@@ -1782,6 +1792,8 @@ int b53_fdb_dump(struct dsa_switch *ds, int port,
 	int ret;
 	u8 reg;
 
+	mutex_lock(&priv->arl_mutex);
+
 	/* Start search operation */
 	reg = ARL_SRCH_STDN;
 	b53_write8(priv, B53_ARLIO_PAGE, B53_ARL_SRCH_CTL, reg);
@@ -1789,18 +1801,18 @@ int b53_fdb_dump(struct dsa_switch *ds, int port,
 	do {
 		ret = b53_arl_search_wait(priv);
 		if (ret)
-			return ret;
+			break;
 
 		b53_arl_search_rd(priv, 0, &results[0]);
 		ret = b53_fdb_copy(port, &results[0], cb, data);
 		if (ret)
-			return ret;
+			break;
 
 		if (priv->num_arl_bins > 2) {
 			b53_arl_search_rd(priv, 1, &results[1]);
 			ret = b53_fdb_copy(port, &results[1], cb, data);
 			if (ret)
-				return ret;
+				break;
 
 			if (!results[0].is_valid && !results[1].is_valid)
 				break;
@@ -1808,6 +1820,8 @@ int b53_fdb_dump(struct dsa_switch *ds, int port,
 
 	} while (count++ < b53_max_arl_entries(priv) / 2);
 
+	mutex_unlock(&priv->arl_mutex);
+
 	return 0;
 }
 EXPORT_SYMBOL(b53_fdb_dump);
@@ -1816,6 +1830,7 @@ int b53_mdb_add(struct dsa_switch *ds, int port,
 		const struct switchdev_obj_port_mdb *mdb)
 {
 	struct b53_device *priv = ds->priv;
+	int ret;
 
 	/* 5325 and 5365 require some more massaging, but could
 	 * be supported eventually
@@ -1823,7 +1838,11 @@ int b53_mdb_add(struct dsa_switch *ds, int port,
 	if (is5325(priv) || is5365(priv))
 		return -EOPNOTSUPP;
 
-	return b53_arl_op(priv, 0, port, mdb->addr, mdb->vid, true);
+	mutex_lock(&priv->arl_mutex);
+	ret = b53_arl_op(priv, 0, port, mdb->addr, mdb->vid, true);
+	mutex_unlock(&priv->arl_mutex);
+
+	return ret;
 }
 EXPORT_SYMBOL(b53_mdb_add);
 
@@ -1833,7 +1852,9 @@ int b53_mdb_del(struct dsa_switch *ds, int port,
 	struct b53_device *priv = ds->priv;
 	int ret;
 
+	mutex_lock(&priv->arl_mutex);
 	ret = b53_arl_op(priv, 0, port, mdb->addr, mdb->vid, false);
+	mutex_unlock(&priv->arl_mutex);
 	if (ret)
 		dev_err(ds->dev, "failed to delete MDB entry\n");
 
@@ -2670,6 +2691,7 @@ struct b53_device *b53_switch_alloc(struct device *base,
 
 	mutex_init(&dev->reg_mutex);
 	mutex_init(&dev->stats_mutex);
+	mutex_init(&dev->arl_mutex);
 
 	return dev;
 }
diff --git a/drivers/net/dsa/b53/b53_priv.h b/drivers/net/dsa/b53/b53_priv.h
index 544101e74bca..579da74ada64 100644
--- a/drivers/net/dsa/b53/b53_priv.h
+++ b/drivers/net/dsa/b53/b53_priv.h
@@ -107,6 +107,7 @@ struct b53_device {
 
 	struct mutex reg_mutex;
 	struct mutex stats_mutex;
+	struct mutex arl_mutex;
 	const struct b53_io_ops *ops;
 
 	/* chip specific data */
-- 
2.25.1

