net: switchdev: remove the transaction structure from port object notifiers

Since the introduction of the switchdev API, port objects were
transmitted to drivers for offloading using a two-step transactional
model, with a prepare phase that was supposed to catch all errors, and a
commit phase that was supposed to never fail.

Some classes of failures can never be avoided, like hardware access, or
memory allocation. In the latter case, merely attempting to move the
memory allocation to the preparation phase makes it impossible to avoid
memory leaks, since commit 91cf8eceffc1 ("switchdev: Remove unused
transaction item queue") which has removed the unused mechanism of
passing on the allocated memory between one phase and another.

It is time we admit that separating the preparation from the commit
phase is something that is best left for the driver to decide, and not
something that should be baked into the API, especially since there are
no switchdev callers that depend on this.

This patch removes the struct switchdev_trans member from switchdev port
object notifier structures, and converts drivers to not look at this
member.

Where driver conversion is trivial (like in the case of the Marvell
Prestera driver, NXP DPAA2 switch, TI CPSW, and Rocker drivers), it is
done in this patch.

Where driver conversion needs more attention (DSA, Mellanox Spectrum),
the conversion is left for subsequent patches and here we only fake the
prepare/commit phases at a lower level, just not in the switchdev
notifier itself.

Where the code has a natural structure that is best left alone as a
preparation and a commit phase (as in the case of the Ocelot switch),
that structure is left in place, just made to not depend upon the
switchdev transactional model.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

5 files changed, 21 insertions, 107 deletions

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 3822520eeeae..9eaa85cc87ea 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -52,7 +52,6 @@ struct dsa_notifier_fdb_info {
 /* DSA_NOTIFIER_MDB_* */
 struct dsa_notifier_mdb_info {
 	const struct switchdev_obj_port_mdb *mdb;
-	struct switchdev_trans *trans;
 	int sw_index;
 	int port;
 };
@@ -60,7 +59,6 @@ struct dsa_notifier_mdb_info {
 /* DSA_NOTIFIER_VLAN_* */
 struct dsa_notifier_vlan_info {
 	const struct switchdev_obj_port_vlan *vlan;
-	struct switchdev_trans *trans;
 	int sw_index;
 	int port;
 };
@@ -151,8 +149,7 @@ int dsa_port_fdb_del(struct dsa_port *dp, const unsigned char *addr,
 		     u16 vid);
 int dsa_port_fdb_dump(struct dsa_port *dp, dsa_fdb_dump_cb_t *cb, void *data);
 int dsa_port_mdb_add(const struct dsa_port *dp,
-		     const struct switchdev_obj_port_mdb *mdb,
-		     struct switchdev_trans *trans);
+		     const struct switchdev_obj_port_mdb *mdb);
 int dsa_port_mdb_del(const struct dsa_port *dp,
 		     const struct switchdev_obj_port_mdb *mdb);
 int dsa_port_pre_bridge_flags(const struct dsa_port *dp, unsigned long flags,
@@ -162,8 +159,7 @@ int dsa_port_bridge_flags(const struct dsa_port *dp, unsigned long flags,
 int dsa_port_mrouter(struct dsa_port *dp, bool mrouter,
 		     struct switchdev_trans *trans);
 int dsa_port_vlan_add(struct dsa_port *dp,
-		      const struct switchdev_obj_port_vlan *vlan,
-		      struct switchdev_trans *trans);
+		      const struct switchdev_obj_port_vlan *vlan);
 int dsa_port_vlan_del(struct dsa_port *dp,
 		      const struct switchdev_obj_port_vlan *vlan);
 int dsa_port_link_register_of(struct dsa_port *dp);
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 73569c9af3cc..6668fe188f47 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -425,13 +425,11 @@ int dsa_port_fdb_dump(struct dsa_port *dp, dsa_fdb_dump_cb_t *cb, void *data)
 }
 
 int dsa_port_mdb_add(const struct dsa_port *dp,
-		     const struct switchdev_obj_port_mdb *mdb,
-		     struct switchdev_trans *trans)
+		     const struct switchdev_obj_port_mdb *mdb)
 {
 	struct dsa_notifier_mdb_info info = {
 		.sw_index = dp->ds->index,
 		.port = dp->index,
-		.trans = trans,
 		.mdb = mdb,
 	};
 
@@ -451,13 +449,11 @@ int dsa_port_mdb_del(const struct dsa_port *dp,
 }
 
 int dsa_port_vlan_add(struct dsa_port *dp,
-		      const struct switchdev_obj_port_vlan *vlan,
-		      struct switchdev_trans *trans)
+		      const struct switchdev_obj_port_vlan *vlan)
 {
 	struct dsa_notifier_vlan_info info = {
 		.sw_index = dp->ds->index,
 		.port = dp->index,
-		.trans = trans,
 		.vlan = vlan,
 	};
 
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 653d64f4a637..0eefb50aae8c 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -326,8 +326,7 @@ dsa_slave_vlan_check_for_8021q_uppers(struct net_device *slave,
 }
 
 static int dsa_slave_vlan_add(struct net_device *dev,
-			      const struct switchdev_obj *obj,
-			      struct switchdev_trans *trans)
+			      const struct switchdev_obj *obj)
 {
 	struct net_device *master = dsa_slave_to_master(dev);
 	struct dsa_port *dp = dsa_slave_to_port(dev);
@@ -345,7 +344,7 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 	/* Deny adding a bridge VLAN when there is already an 802.1Q upper with
 	 * the same VID.
 	 */
-	if (trans->ph_prepare && br_vlan_enabled(dp->bridge_dev)) {
+	if (br_vlan_enabled(dp->bridge_dev)) {
 		rcu_read_lock();
 		err = dsa_slave_vlan_check_for_8021q_uppers(dev, &vlan);
 		rcu_read_unlock();
@@ -353,7 +352,7 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 			return err;
 	}
 
-	err = dsa_port_vlan_add(dp, &vlan, trans);
+	err = dsa_port_vlan_add(dp, &vlan);
 	if (err)
 		return err;
 
@@ -363,7 +362,7 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 	 */
 	vlan.flags &= ~BRIDGE_VLAN_INFO_PVID;
 
-	err = dsa_port_vlan_add(dp->cpu_dp, &vlan, trans);
+	err = dsa_port_vlan_add(dp->cpu_dp, &vlan);
 	if (err)
 		return err;
 
@@ -372,7 +371,6 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 
 static int dsa_slave_port_obj_add(struct net_device *dev,
 				  const struct switchdev_obj *obj,
-				  struct switchdev_trans *trans,
 				  struct netlink_ext_ack *extack)
 {
 	struct dsa_port *dp = dsa_slave_to_port(dev);
@@ -387,17 +385,16 @@ static int dsa_slave_port_obj_add(struct net_device *dev,
 	case SWITCHDEV_OBJ_ID_PORT_MDB:
 		if (obj->orig_dev != dev)
 			return -EOPNOTSUPP;
-		err = dsa_port_mdb_add(dp, SWITCHDEV_OBJ_PORT_MDB(obj), trans);
+		err = dsa_port_mdb_add(dp, SWITCHDEV_OBJ_PORT_MDB(obj));
 		break;
 	case SWITCHDEV_OBJ_ID_HOST_MDB:
 		/* DSA can directly translate this to a normal MDB add,
 		 * but on the CPU port.
 		 */
-		err = dsa_port_mdb_add(dp->cpu_dp, SWITCHDEV_OBJ_PORT_MDB(obj),
-				       trans);
+		err = dsa_port_mdb_add(dp->cpu_dp, SWITCHDEV_OBJ_PORT_MDB(obj));
 		break;
 	case SWITCHDEV_OBJ_ID_PORT_VLAN:
-		err = dsa_slave_vlan_add(dev, obj, trans);
+		err = dsa_slave_vlan_add(dev, obj);
 		break;
 	default:
 		err = -EOPNOTSUPP;
@@ -1286,28 +1283,15 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
 		/* This API only allows programming tagged, non-PVID VIDs */
 		.flags = 0,
 	};
-	struct switchdev_trans trans;
 	int ret;
 
 	/* User port... */
-	trans.ph_prepare = true;
-	ret = dsa_port_vlan_add(dp, &vlan, &trans);
-	if (ret)
-		return ret;
-
-	trans.ph_prepare = false;
-	ret = dsa_port_vlan_add(dp, &vlan, &trans);
+	ret = dsa_port_vlan_add(dp, &vlan);
 	if (ret)
 		return ret;
 
 	/* And CPU port... */
-	trans.ph_prepare = true;
-	ret = dsa_port_vlan_add(dp->cpu_dp, &vlan, &trans);
-	if (ret)
-		return ret;
-
-	trans.ph_prepare = false;
-	ret = dsa_port_vlan_add(dp->cpu_dp, &vlan, &trans);
+	ret = dsa_port_vlan_add(dp->cpu_dp, &vlan);
 	if (ret)
 		return ret;
 
diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index 3fb362b6874e..5b0bf29e1375 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -190,8 +190,8 @@ static bool dsa_switch_mdb_match(struct dsa_switch *ds, int port,
 	return false;
 }
 
-static int dsa_switch_mdb_prepare(struct dsa_switch *ds,
-				  struct dsa_notifier_mdb_info *info)
+static int dsa_switch_mdb_add(struct dsa_switch *ds,
+			      struct dsa_notifier_mdb_info *info)
 {
 	int port, err;
 
@@ -206,20 +206,6 @@ static int dsa_switch_mdb_prepare(struct dsa_switch *ds,
 		}
 	}
 
-	return 0;
-}
-
-static int dsa_switch_mdb_add(struct dsa_switch *ds,
-			      struct dsa_notifier_mdb_info *info)
-{
-	int port;
-
-	if (switchdev_trans_ph_prepare(info->trans))
-		return dsa_switch_mdb_prepare(ds, info);
-
-	if (!ds->ops->port_mdb_add)
-		return 0;
-
 	for (port = 0; port < ds->num_ports; port++)
 		if (dsa_switch_mdb_match(ds, port, info))
 			ds->ops->port_mdb_add(ds, port, info->mdb);
@@ -251,8 +237,8 @@ static bool dsa_switch_vlan_match(struct dsa_switch *ds, int port,
 	return false;
 }
 
-static int dsa_switch_vlan_prepare(struct dsa_switch *ds,
-				   struct dsa_notifier_vlan_info *info)
+static int dsa_switch_vlan_add(struct dsa_switch *ds,
+			       struct dsa_notifier_vlan_info *info)
 {
 	int port, err;
 
@@ -267,20 +253,6 @@ static int dsa_switch_vlan_prepare(struct dsa_switch *ds,
 		}
 	}
 
-	return 0;
-}
-
-static int dsa_switch_vlan_add(struct dsa_switch *ds,
-			       struct dsa_notifier_vlan_info *info)
-{
-	int port;
-
-	if (switchdev_trans_ph_prepare(info->trans))
-		return dsa_switch_vlan_prepare(ds, info);
-
-	if (!ds->ops->port_vlan_add)
-		return 0;
-
 	for (port = 0; port < ds->num_ports; port++)
 		if (dsa_switch_vlan_match(ds, port, info))
 			ds->ops->port_vlan_add(ds, port, info->vlan);
diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index 23d868545362..a575bb33ee6c 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -221,7 +221,6 @@ static size_t switchdev_obj_size(const struct switchdev_obj *obj)
 static int switchdev_port_obj_notify(enum switchdev_notifier_type nt,
 				     struct net_device *dev,
 				     const struct switchdev_obj *obj,
-				     struct switchdev_trans *trans,
 				     struct netlink_ext_ack *extack)
 {
 	int rc;
@@ -229,7 +228,6 @@ static int switchdev_port_obj_notify(enum switchdev_notifier_type nt,
 
 	struct switchdev_notifier_port_obj_info obj_info = {
 		.obj = obj,
-		.trans = trans,
 		.handled = false,
 	};
 
@@ -248,35 +246,10 @@ static int switchdev_port_obj_add_now(struct net_device *dev,
 				      const struct switchdev_obj *obj,
 				      struct netlink_ext_ack *extack)
 {
-	struct switchdev_trans trans;
-	int err;
-
 	ASSERT_RTNL();
 
-	/* Phase I: prepare for obj add. Driver/device should fail
-	 * here if there are going to be issues in the commit phase,
-	 * such as lack of resources or support.  The driver/device
-	 * should reserve resources needed for the commit phase here,
-	 * but should not commit the obj.
-	 */
-
-	trans.ph_prepare = true;
-	err = switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_ADD,
-					dev, obj, &trans, extack);
-	if (err)
-		return err;
-
-	/* Phase II: commit obj add.  This cannot fail as a fault
-	 * of driver/device.  If it does, it's a bug in the driver/device
-	 * because the driver said everythings was OK in phase I.
-	 */
-
-	trans.ph_prepare = false;
-	err = switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_ADD,
-					dev, obj, &trans, extack);
-	WARN(err, "%s: Commit of object (id=%d) failed.\n", dev->name, obj->id);
-
-	return err;
+	return switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_ADD,
+					 dev, obj, extack);
 }
 
 static void switchdev_port_obj_add_deferred(struct net_device *dev,
@@ -307,10 +280,6 @@ static int switchdev_port_obj_add_defer(struct net_device *dev,
  *	@obj: object to add
  *	@extack: netlink extended ack
  *
- *	Use a 2-phase prepare-commit transaction model to ensure
- *	system is not left in a partially updated state due to
- *	failure from driver/device.
- *
  *	rtnl_lock must be held and must not be in atomic section,
  *	in case SWITCHDEV_F_DEFER flag is not set.
  */
@@ -329,7 +298,7 @@ static int switchdev_port_obj_del_now(struct net_device *dev,
 				      const struct switchdev_obj *obj)
 {
 	return switchdev_port_obj_notify(SWITCHDEV_PORT_OBJ_DEL,
-					 dev, obj, NULL, NULL);
+					 dev, obj, NULL);
 }
 
 static void switchdev_port_obj_del_deferred(struct net_device *dev,
@@ -449,7 +418,6 @@ static int __switchdev_handle_port_obj_add(struct net_device *dev,
 			bool (*check_cb)(const struct net_device *dev),
 			int (*add_cb)(struct net_device *dev,
 				      const struct switchdev_obj *obj,
-				      struct switchdev_trans *trans,
 				      struct netlink_ext_ack *extack))
 {
 	struct netlink_ext_ack *extack;
@@ -462,8 +430,7 @@ static int __switchdev_handle_port_obj_add(struct net_device *dev,
 	if (check_cb(dev)) {
 		/* This flag is only checked if the return value is success. */
 		port_obj_info->handled = true;
-		return add_cb(dev, port_obj_info->obj, port_obj_info->trans,
-			      extack);
+		return add_cb(dev, port_obj_info->obj, extack);
 	}
 
 	/* Switch ports might be stacked under e.g. a LAG. Ignore the
@@ -491,7 +458,6 @@ int switchdev_handle_port_obj_add(struct net_device *dev,
 			bool (*check_cb)(const struct net_device *dev),
 			int (*add_cb)(struct net_device *dev,
 				      const struct switchdev_obj *obj,
-				      struct switchdev_trans *trans,
 				      struct netlink_ext_ack *extack))
 {
 	int err;