net: switchdev: remove the transaction structure from port attributes

Since the introduction of the switchdev API, port attributes 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
attribute notifier structures, and converts drivers to not look at this
member.

In part, this patch contains a revert of my previous commit 2e554a7a5d8a
("net: dsa: propagate switchdev vlan_filtering prepare phase to
drivers").

For the most part, the conversion was trivial except for:
- Rocker's world implementation based on Broadcom OF-DPA had an odd
  implementation of ofdpa_port_attr_bridge_flags_set. The conversion was
  done mechanically, by pasting the implementation twice, then only
  keeping the code that would get executed during prepare phase on top,
  then only keeping the code that gets executed during the commit phase
  on bottom, then simplifying the resulting code until this was obtained.
- DSA's offloading of STP state, bridge flags, VLAN filtering and
  multicast router could be converted right away. But the ageing time
  could not, so a shim was introduced and this was left for a further
  commit.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de> # hellcreek
Reviewed-by: Linus Walleij <linus.walleij@linaro.org> # RTL8366RB
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 43 insertions, 54 deletions

diff --git a/net/dsa/port.c b/net/dsa/port.c
index 6668fe188f47..14bf0053ae01 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -40,17 +40,15 @@ static int dsa_port_notify(const struct dsa_port *dp, unsigned long e, void *v)
 	return notifier_to_errno(err);
 }
 
-int dsa_port_set_state(struct dsa_port *dp, u8 state,
-		       struct switchdev_trans *trans)
+int dsa_port_set_state(struct dsa_port *dp, u8 state)
 {
 	struct dsa_switch *ds = dp->ds;
 	int port = dp->index;
 
-	if (switchdev_trans_ph_prepare(trans))
-		return ds->ops->port_stp_state_set ? 0 : -EOPNOTSUPP;
+	if (!ds->ops->port_stp_state_set)
+		return -EOPNOTSUPP;
 
-	if (ds->ops->port_stp_state_set)
-		ds->ops->port_stp_state_set(ds, port, state);
+	ds->ops->port_stp_state_set(ds, port, state);
 
 	if (ds->ops->port_fast_age) {
 		/* Fast age FDB entries or flush appropriate forwarding database
@@ -75,7 +73,7 @@ static void dsa_port_set_state_now(struct dsa_port *dp, u8 state)
 {
 	int err;
 
-	err = dsa_port_set_state(dp, state, NULL);
+	err = dsa_port_set_state(dp, state);
 	if (err)
 		pr_err("DSA: failed to set STP state %u (%d)\n", state, err);
 }
@@ -145,7 +143,7 @@ int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br)
 	int err;
 
 	/* Set the flooding mode before joining the port in the switch */
-	err = dsa_port_bridge_flags(dp, BR_FLOOD | BR_MCAST_FLOOD, NULL);
+	err = dsa_port_bridge_flags(dp, BR_FLOOD | BR_MCAST_FLOOD);
 	if (err)
 		return err;
 
@@ -158,7 +156,7 @@ int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br)
 
 	/* The bridging is rolled back on error */
 	if (err) {
-		dsa_port_bridge_flags(dp, 0, NULL);
+		dsa_port_bridge_flags(dp, 0);
 		dp->bridge_dev = NULL;
 	}
 
@@ -185,7 +183,7 @@ void dsa_port_bridge_leave(struct dsa_port *dp, struct net_device *br)
 		pr_err("DSA: failed to notify DSA_NOTIFIER_BRIDGE_LEAVE\n");
 
 	/* Port is leaving the bridge, disable flooding */
-	dsa_port_bridge_flags(dp, 0, NULL);
+	dsa_port_bridge_flags(dp, 0);
 
 	/* Port left the bridge, put in BR_STATE_DISABLED by the bridge layer,
 	 * so allow it to be in BR_STATE_FORWARDING to be kept functional
@@ -259,43 +257,36 @@ static bool dsa_port_can_apply_vlan_filtering(struct dsa_port *dp,
 	return true;
 }
 
-int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering,
-			    struct switchdev_trans *trans)
+int dsa_port_vlan_filtering(struct dsa_port *dp, bool vlan_filtering)
 {
 	struct dsa_switch *ds = dp->ds;
+	bool apply;
 	int err;
 
-	if (switchdev_trans_ph_prepare(trans)) {
-		bool apply;
-
-		if (!ds->ops->port_vlan_filtering)
-			return -EOPNOTSUPP;
+	if (!ds->ops->port_vlan_filtering)
+		return -EOPNOTSUPP;
 
-		/* We are called from dsa_slave_switchdev_blocking_event(),
-		 * which is not under rcu_read_lock(), unlike
-		 * dsa_slave_switchdev_event().
-		 */
-		rcu_read_lock();
-		apply = dsa_port_can_apply_vlan_filtering(dp, vlan_filtering);
-		rcu_read_unlock();
-		if (!apply)
-			return -EINVAL;
-	}
+	/* We are called from dsa_slave_switchdev_blocking_event(),
+	 * which is not under rcu_read_lock(), unlike
+	 * dsa_slave_switchdev_event().
+	 */
+	rcu_read_lock();
+	apply = dsa_port_can_apply_vlan_filtering(dp, vlan_filtering);
+	rcu_read_unlock();
+	if (!apply)
+		return -EINVAL;
 
 	if (dsa_port_is_vlan_filtering(dp) == vlan_filtering)
 		return 0;
 
-	err = ds->ops->port_vlan_filtering(ds, dp->index, vlan_filtering,
-					   trans);
+	err = ds->ops->port_vlan_filtering(ds, dp->index, vlan_filtering);
 	if (err)
 		return err;
 
-	if (switchdev_trans_ph_commit(trans)) {
-		if (ds->vlan_filtering_is_global)
-			ds->vlan_filtering = vlan_filtering;
-		else
-			dp->vlan_filtering = vlan_filtering;
-	}
+	if (ds->vlan_filtering_is_global)
+		ds->vlan_filtering = vlan_filtering;
+	else
+		dp->vlan_filtering = vlan_filtering;
 
 	return 0;
 }
@@ -314,26 +305,29 @@ bool dsa_port_skip_vlan_configuration(struct dsa_port *dp)
 		!br_vlan_enabled(dp->bridge_dev));
 }
 
-int dsa_port_ageing_time(struct dsa_port *dp, clock_t ageing_clock,
-			 struct switchdev_trans *trans)
+int dsa_port_ageing_time(struct dsa_port *dp, clock_t ageing_clock)
 {
 	unsigned long ageing_jiffies = clock_t_to_jiffies(ageing_clock);
 	unsigned int ageing_time = jiffies_to_msecs(ageing_jiffies);
-	struct dsa_notifier_ageing_time_info info = {
-		.ageing_time = ageing_time,
-		.trans = trans,
-	};
+	struct dsa_notifier_ageing_time_info info;
+	struct switchdev_trans trans;
+	int err;
 
-	if (switchdev_trans_ph_prepare(trans))
-		return dsa_port_notify(dp, DSA_NOTIFIER_AGEING_TIME, &info);
+	info.ageing_time = ageing_time;
+	info.trans = &trans;
+
+	trans.ph_prepare = true;
+	err = dsa_port_notify(dp, DSA_NOTIFIER_AGEING_TIME, &info);
+	if (err)
+		return err;
 
 	dp->ageing_time = ageing_time;
 
+	trans.ph_prepare = false;
 	return dsa_port_notify(dp, DSA_NOTIFIER_AGEING_TIME, &info);
 }
 
-int dsa_port_pre_bridge_flags(const struct dsa_port *dp, unsigned long flags,
-			      struct switchdev_trans *trans)
+int dsa_port_pre_bridge_flags(const struct dsa_port *dp, unsigned long flags)
 {
 	struct dsa_switch *ds = dp->ds;
 
@@ -344,16 +338,12 @@ int dsa_port_pre_bridge_flags(const struct dsa_port *dp, unsigned long flags,
 	return 0;
 }
 
-int dsa_port_bridge_flags(const struct dsa_port *dp, unsigned long flags,
-			  struct switchdev_trans *trans)
+int dsa_port_bridge_flags(const struct dsa_port *dp, unsigned long flags)
 {
 	struct dsa_switch *ds = dp->ds;
 	int port = dp->index;
 	int err = 0;
 
-	if (switchdev_trans_ph_prepare(trans))
-		return 0;
-
 	if (ds->ops->port_egress_floods)
 		err = ds->ops->port_egress_floods(ds, port, flags & BR_FLOOD,
 						  flags & BR_MCAST_FLOOD);
@@ -361,14 +351,13 @@ int dsa_port_bridge_flags(const struct dsa_port *dp, unsigned long flags,
 	return err;
 }
 
-int dsa_port_mrouter(struct dsa_port *dp, bool mrouter,
-		     struct switchdev_trans *trans)
+int dsa_port_mrouter(struct dsa_port *dp, bool mrouter)
 {
 	struct dsa_switch *ds = dp->ds;
 	int port = dp->index;
 
-	if (switchdev_trans_ph_prepare(trans))
-		return ds->ops->port_egress_floods ? 0 : -EOPNOTSUPP;
+	if (!ds->ops->port_egress_floods)
+		return -EOPNOTSUPP;
 
 	return ds->ops->port_egress_floods(ds, port, true, mrouter);
 }