net: mscc: ocelot: extend ocelot->fwd_domain_lock to cover ocelot->tas_lock

In a future commit we will have to call vsc9959_tas_guard_bands_update()
from ocelot_port_update_active_preemptible_tcs(), and that will be
impossible due to the AB/BA locking dependencies between
ocelot->tas_lock and ocelot->fwd_domain_lock.

Just like we did in commit 3ff468ef ("net: mscc: ocelot: remove
struct ocelot_mm_state :: lock"), the only solution is to expand the
scope of ocelot->fwd_domain_lock for it to also serialize changes made
to the Time-Aware Shaper, because those will have to result in a
recalculation of cut-through TCs, which is something that depends on the
forwarding domain.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Message-ID: <20230705104422.49025-2-vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/ocelot/felix.c

@@ -1790,12 +1790,12 @@ static int felix_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
 
 	ocelot_port_set_maxlen(ocelot, port, new_mtu);
 
-	mutex_lock(&ocelot->tas_lock);
+	mutex_lock(&ocelot->fwd_domain_lock);
 
 	if (ocelot_port->taprio && felix->info->tas_guard_bands_update)
 		felix->info->tas_guard_bands_update(ocelot, port);
 
-	mutex_unlock(&ocelot->tas_lock);
+	mutex_unlock(&ocelot->fwd_domain_lock);
 
 	return 0;
 }

drivers/net/dsa/ocelot/felix_vsc9959.c

@@ -1217,7 +1217,7 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
 	u8 tas_speed;
 	int tc;
 
-	lockdep_assert_held(&ocelot->tas_lock);
+	lockdep_assert_held(&ocelot->fwd_domain_lock);
 
 	taprio = ocelot_port->taprio;
 
@@ -1259,8 +1259,6 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
 
 	vsc9959_tas_min_gate_lengths(taprio, min_gate_len);
 
-	mutex_lock(&ocelot->fwd_domain_lock);
-
 	for (tc = 0; tc < OCELOT_NUM_TC; tc++) {
 		u32 requested_max_sdu = vsc9959_tas_tc_max_sdu(taprio, tc);
 		u64 remaining_gate_len_ps;
@@ -1323,8 +1321,6 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
 	ocelot_write_rix(ocelot, maxlen, QSYS_PORT_MAX_SDU, port);
 
 	ocelot->ops->cut_through_fwd(ocelot);
-
-	mutex_unlock(&ocelot->fwd_domain_lock);
 }
 
 static void vsc9959_sched_speed_set(struct ocelot *ocelot, int port,
@@ -1351,7 +1347,7 @@ static void vsc9959_sched_speed_set(struct ocelot *ocelot, int port,
 		break;
 	}
 
-	mutex_lock(&ocelot->tas_lock);
+	mutex_lock(&ocelot->fwd_domain_lock);
 
 	ocelot_rmw_rix(ocelot,
 		       QSYS_TAG_CONFIG_LINK_SPEED(tas_speed),
@@ -1361,7 +1357,7 @@ static void vsc9959_sched_speed_set(struct ocelot *ocelot, int port,
 	if (ocelot_port->taprio)
 		vsc9959_tas_guard_bands_update(ocelot, port);
 
-	mutex_unlock(&ocelot->tas_lock);
+	mutex_unlock(&ocelot->fwd_domain_lock);
 }
 
 static void vsc9959_new_base_time(struct ocelot *ocelot, ktime_t base_time,
@@ -1409,7 +1405,7 @@ static int vsc9959_qos_port_tas_set(struct ocelot *ocelot, int port,
 	int ret, i;
 	u32 val;
 
-	mutex_lock(&ocelot->tas_lock);
+	mutex_lock(&ocelot->fwd_domain_lock);
 
 	if (taprio->cmd == TAPRIO_CMD_DESTROY) {
 		ocelot_port_mqprio(ocelot, port, &taprio->mqprio);
@@ -1421,7 +1417,7 @@ static int vsc9959_qos_port_tas_set(struct ocelot *ocelot, int port,
 
 		vsc9959_tas_guard_bands_update(ocelot, port);
 
-		mutex_unlock(&ocelot->tas_lock);
+		mutex_unlock(&ocelot->fwd_domain_lock);
 		return 0;
 	} else if (taprio->cmd != TAPRIO_CMD_REPLACE) {
 		ret = -EOPNOTSUPP;
@@ -1504,7 +1500,7 @@ static int vsc9959_qos_port_tas_set(struct ocelot *ocelot, int port,
 	ocelot_port->taprio = taprio_offload_get(taprio);
 	vsc9959_tas_guard_bands_update(ocelot, port);
 
-	mutex_unlock(&ocelot->tas_lock);
+	mutex_unlock(&ocelot->fwd_domain_lock);
 
 	return 0;
 
@@ -1512,7 +1508,7 @@ static int vsc9959_qos_port_tas_set(struct ocelot *ocelot, int port,
 	taprio->mqprio.qopt.num_tc = 0;
 	ocelot_port_mqprio(ocelot, port, &taprio->mqprio);
 err_unlock:
-	mutex_unlock(&ocelot->tas_lock);
+	mutex_unlock(&ocelot->fwd_domain_lock);
 
 	return ret;
 }
@@ -1525,7 +1521,7 @@ static void vsc9959_tas_clock_adjust(struct ocelot *ocelot)
 	int port;
 	u32 val;
 
-	mutex_lock(&ocelot->tas_lock);
+	mutex_lock(&ocelot->fwd_domain_lock);
 
 	for (port = 0; port < ocelot->num_phys_ports; port++) {
 		ocelot_port = ocelot->ports[port];
@@ -1563,7 +1559,7 @@ static void vsc9959_tas_clock_adjust(struct ocelot *ocelot)
 			       QSYS_TAG_CONFIG_ENABLE,
 			       QSYS_TAG_CONFIG, port);
 	}
-	mutex_unlock(&ocelot->tas_lock);
+	mutex_unlock(&ocelot->fwd_domain_lock);
 }
 
 static int vsc9959_qos_port_cbs_set(struct dsa_switch *ds, int port,
@@ -1634,6 +1630,18 @@ static int vsc9959_qos_query_caps(struct tc_query_caps_base *base)
 	}
 }
 
+static int vsc9959_qos_port_mqprio(struct ocelot *ocelot, int port,
+				   struct tc_mqprio_qopt_offload *mqprio)
+{
+	int ret;
+
+	mutex_lock(&ocelot->fwd_domain_lock);
+	ret = ocelot_port_mqprio(ocelot, port, mqprio);
+	mutex_unlock(&ocelot->fwd_domain_lock);
+
+	return ret;
+}
+
 static int vsc9959_port_setup_tc(struct dsa_switch *ds, int port,
 				 enum tc_setup_type type,
 				 void *type_data)
@@ -1646,7 +1654,7 @@ static int vsc9959_port_setup_tc(struct dsa_switch *ds, int port,
 	case TC_SETUP_QDISC_TAPRIO:
 		return vsc9959_qos_port_tas_set(ocelot, port, type_data);
 	case TC_SETUP_QDISC_MQPRIO:
-		return ocelot_port_mqprio(ocelot, port, type_data);
+		return vsc9959_qos_port_mqprio(ocelot, port, type_data);
 	case TC_SETUP_QDISC_CBS:
 		return vsc9959_qos_port_cbs_set(ds, port, type_data);
 	default:

drivers/net/ethernet/mscc/ocelot.c

@@ -2927,7 +2927,6 @@ int ocelot_init(struct ocelot *ocelot)
 
 	mutex_init(&ocelot->mact_lock);
 	mutex_init(&ocelot->fwd_domain_lock);
-	mutex_init(&ocelot->tas_lock);
 	spin_lock_init(&ocelot->ptp_clock_lock);
 	spin_lock_init(&ocelot->ts_id_lock);
 

drivers/net/ethernet/mscc/ocelot_mm.c

@@ -89,17 +89,14 @@ void ocelot_port_change_fp(struct ocelot *ocelot, int port,
 {
 	struct ocelot_mm_state *mm = &ocelot->mm[port];
 
-	mutex_lock(&ocelot->fwd_domain_lock);
+	lockdep_assert_held(&ocelot->fwd_domain_lock);
 
 	if (mm->preemptible_tcs == preemptible_tcs)
-		goto out_unlock;
+		return;
 
 	mm->preemptible_tcs = preemptible_tcs;
 
 	ocelot_port_update_active_preemptible_tcs(ocelot, port);
-
-out_unlock:
-	mutex_unlock(&ocelot->fwd_domain_lock);
 }
 
 static void ocelot_mm_update_port_status(struct ocelot *ocelot, int port)

include/soc/mscc/ocelot.h

@@ -863,12 +863,12 @@ struct ocelot {
 	struct mutex			stat_view_lock;
 	/* Lock for serializing access to the MAC table */
 	struct mutex			mact_lock;
-	/* Lock for serializing forwarding domain changes */
+	/* Lock for serializing forwarding domain changes, including the
+	 * configuration of the Time-Aware Shaper, MAC Merge layer and
+	 * cut-through forwarding, on which it depends
+	 */
 	struct mutex			fwd_domain_lock;
 
-	/* Lock for serializing Time-Aware Shaper changes */
-	struct mutex			tas_lock;
-
 	struct workqueue_struct		*owq;
 
 	u8				ptp:1;