net: dsa: sja1105: serialize sja1105_port_mcast_flood() with other FDB accesses

sja1105_fdb_add() runs from the dsa_owq, and sja1105_port_mcast_flood()
runs from switchdev_deferred_process_work(). Prior to the blamed commit,
they used to be indirectly serialized through the rtnl_lock(), which
no longer holds true because dsa_owq dropped that.

So, it is now possible that we traverse the static config BLK_IDX_L2_LOOKUP
elements concurrently compared to when we change them, in
sja1105_static_fdb_change(). That is not ideal, since it might result in
data corruption.

Introduce a mutex which serializes accesses to the hardware FDB and to
the static config elements for the L2 Address Lookup table.

I can't find a good reason to add locking around sja1105_fdb_dump().
I'll add it later if needed.

Fixes: 0faf890fc519 ("net: dsa: drop rtnl_lock from dsa_slave_switchdev_event_work")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h
index 0617d5ccd3ff104b63bac4711a8686f2ad2179f2..8c66d3bf61f028167a98fd7025ba6b0f7b3b431d 100644 (file)
--- a/drivers/net/dsa/sja1105/sja1105.h
+++ b/drivers/net/dsa/sja1105/sja1105.h
@@ -266,6 +266,8 @@ struct sja1105_private {
         * the switch doesn't confuse them with one another.
         */
        struct mutex mgmt_lock;
+       /* Serializes accesses to the FDB */
+       struct mutex fdb_lock;
        /* PTP two-step TX timestamp ID, and its serialization lock */
        spinlock_t ts_id_lock;
        u8 ts_id;

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 11c917d5ce436890a6e8f4e779494384c1b473a9..cefd72617af4dd6d90a40fbc2d7795d5ca324205 100644 (file)
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -1798,6 +1798,7 @@ static int sja1105_fdb_add(struct dsa_switch *ds, int port,
                           struct dsa_db db)
 {
        struct sja1105_private *priv = ds->priv;
+       int rc;
 
        if (!vid) {
                switch (db.type) {
@@ -1812,12 +1813,16 @@ static int sja1105_fdb_add(struct dsa_switch *ds, int port,
                }
        }
 
-       return priv->info->fdb_add_cmd(ds, port, addr, vid);
+       mutex_lock(&priv->fdb_lock);
+       rc = priv->info->fdb_add_cmd(ds, port, addr, vid);
+       mutex_unlock(&priv->fdb_lock);
+
+       return rc;
 }
 
-static int sja1105_fdb_del(struct dsa_switch *ds, int port,
-                          const unsigned char *addr, u16 vid,
-                          struct dsa_db db)
+static int __sja1105_fdb_del(struct dsa_switch *ds, int port,
+                            const unsigned char *addr, u16 vid,
+                            struct dsa_db db)
 {
        struct sja1105_private *priv = ds->priv;
 
@@ -1837,6 +1842,20 @@ static int sja1105_fdb_del(struct dsa_switch *ds, int port,
        return priv->info->fdb_del_cmd(ds, port, addr, vid);
 }
 
+static int sja1105_fdb_del(struct dsa_switch *ds, int port,
+                          const unsigned char *addr, u16 vid,
+                          struct dsa_db db)
+{
+       struct sja1105_private *priv = ds->priv;
+       int rc;
+
+       mutex_lock(&priv->fdb_lock);
+       rc = __sja1105_fdb_del(ds, port, addr, vid, db);
+       mutex_unlock(&priv->fdb_lock);
+
+       return rc;
+}
+
 static int sja1105_fdb_dump(struct dsa_switch *ds, int port,
                            dsa_fdb_dump_cb_t *cb, void *data)
 {
@@ -1899,6 +1918,8 @@ static void sja1105_fast_age(struct dsa_switch *ds, int port)
        };
        int i;
 
+       mutex_lock(&priv->fdb_lock);
+
        for (i = 0; i < SJA1105_MAX_L2_LOOKUP_COUNT; i++) {
                struct sja1105_l2_lookup_entry l2_lookup = {0};
                u8 macaddr[ETH_ALEN];
@@ -1912,7 +1933,7 @@ static void sja1105_fast_age(struct dsa_switch *ds, int port)
                if (rc) {
                        dev_err(ds->dev, "Failed to read FDB: %pe\n",
                                ERR_PTR(rc));
-                       return;
+                       break;
                }
 
                if (!(l2_lookup.destports & BIT(port)))
@@ -1924,14 +1945,16 @@ static void sja1105_fast_age(struct dsa_switch *ds, int port)
 
                u64_to_ether_addr(l2_lookup.macaddr, macaddr);
 
-               rc = sja1105_fdb_del(ds, port, macaddr, l2_lookup.vlanid, db);
+               rc = __sja1105_fdb_del(ds, port, macaddr, l2_lookup.vlanid, db);
                if (rc) {
                        dev_err(ds->dev,
                                "Failed to delete FDB entry %pM vid %lld: %pe\n",
                                macaddr, l2_lookup.vlanid, ERR_PTR(rc));
-                       return;
+                       break;
                }
        }
+
+       mutex_unlock(&priv->fdb_lock);
 }
 
 static int sja1105_mdb_add(struct dsa_switch *ds, int port,
@@ -2955,7 +2978,9 @@ static int sja1105_port_mcast_flood(struct sja1105_private *priv, int to,
 {
        struct sja1105_l2_lookup_entry *l2_lookup;
        struct sja1105_table *table;
-       int match;
+       int match, rc;
+
+       mutex_lock(&priv->fdb_lock);
 
        table = &priv->static_config.tables[BLK_IDX_L2_LOOKUP];
        l2_lookup = table->entries;
@@ -2968,7 +2993,8 @@ static int sja1105_port_mcast_flood(struct sja1105_private *priv, int to,
        if (match == table->entry_count) {
                NL_SET_ERR_MSG_MOD(extack,
                                   "Could not find FDB entry for unknown multicast");
-               return -ENOSPC;
+               rc = -ENOSPC;
+               goto out;
        }
 
        if (flags.val & BR_MCAST_FLOOD)
@@ -2976,10 +3002,13 @@ static int sja1105_port_mcast_flood(struct sja1105_private *priv, int to,
        else
                l2_lookup[match].destports &= ~BIT(to);
 
-       return sja1105_dynamic_config_write(priv, BLK_IDX_L2_LOOKUP,
-                                           l2_lookup[match].index,
-                                           &l2_lookup[match],
-                                           true);
+       rc = sja1105_dynamic_config_write(priv, BLK_IDX_L2_LOOKUP,
+                                         l2_lookup[match].index,
+                                         &l2_lookup[match], true);
+out:
+       mutex_unlock(&priv->fdb_lock);
+
+       return rc;
 }
 
 static int sja1105_port_pre_bridge_flags(struct dsa_switch *ds, int port,
@@ -3349,6 +3378,7 @@ static int sja1105_probe(struct spi_device *spi)
        mutex_init(&priv->ptp_data.lock);
        mutex_init(&priv->dynamic_config_lock);
        mutex_init(&priv->mgmt_lock);
+       mutex_init(&priv->fdb_lock);
        spin_lock_init(&priv->ts_id_lock);
 
        rc = sja1105_parse_dt(priv);