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, 5 insertions, 16 deletions

diff --git a/drivers/staging/fsl-dpaa2/ethsw/ethsw.c b/drivers/staging/fsl-dpaa2/ethsw/ethsw.c
index 197dea9c3b42..ca3d07fe7f58 100644
--- a/drivers/staging/fsl-dpaa2/ethsw/ethsw.c
+++ b/drivers/staging/fsl-dpaa2/ethsw/ethsw.c
@@ -901,19 +901,14 @@ static void dpaa2_switch_teardown_irqs(struct fsl_mc_device *sw_dev)
 }
 
 static int dpaa2_switch_port_attr_stp_state_set(struct net_device *netdev,
-						struct switchdev_trans *trans,
 						u8 state)
 {
 	struct ethsw_port_priv *port_priv = netdev_priv(netdev);
 
-	if (switchdev_trans_ph_prepare(trans))
-		return 0;
-
 	return dpaa2_switch_port_set_stp_state(port_priv, state);
 }
 
 static int dpaa2_switch_port_attr_br_flags_pre_set(struct net_device *netdev,
-						   struct switchdev_trans *trans,
 						   unsigned long flags)
 {
 	if (flags & ~(BR_LEARNING | BR_FLOOD))
@@ -923,15 +918,11 @@ static int dpaa2_switch_port_attr_br_flags_pre_set(struct net_device *netdev,
 }
 
 static int dpaa2_switch_port_attr_br_flags_set(struct net_device *netdev,
-					       struct switchdev_trans *trans,
 					       unsigned long flags)
 {
 	struct ethsw_port_priv *port_priv = netdev_priv(netdev);
 	int err = 0;
 
-	if (switchdev_trans_ph_prepare(trans))
-		return 0;
-
 	/* Learning is enabled per switch */
 	err = dpaa2_switch_set_learning(port_priv->ethsw_data,
 					!!(flags & BR_LEARNING));
@@ -945,22 +936,21 @@ exit:
 }
 
 static int dpaa2_switch_port_attr_set(struct net_device *netdev,
-				      const struct switchdev_attr *attr,
-				      struct switchdev_trans *trans)
+				      const struct switchdev_attr *attr)
 {
 	int err = 0;
 
 	switch (attr->id) {
 	case SWITCHDEV_ATTR_ID_PORT_STP_STATE:
-		err = dpaa2_switch_port_attr_stp_state_set(netdev, trans,
+		err = dpaa2_switch_port_attr_stp_state_set(netdev,
 							   attr->u.stp_state);
 		break;
 	case SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS:
-		err = dpaa2_switch_port_attr_br_flags_pre_set(netdev, trans,
+		err = dpaa2_switch_port_attr_br_flags_pre_set(netdev,
 							      attr->u.brport_flags);
 		break;
 	case SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS:
-		err = dpaa2_switch_port_attr_br_flags_set(netdev, trans,
+		err = dpaa2_switch_port_attr_br_flags_set(netdev,
 							  attr->u.brport_flags);
 		break;
 	case SWITCHDEV_ATTR_ID_BRIDGE_VLAN_FILTERING:
@@ -1197,8 +1187,7 @@ static int dpaa2_switch_port_attr_set_event(struct net_device *netdev,
 {
 	int err;
 
-	err = dpaa2_switch_port_attr_set(netdev, port_attr_info->attr,
-					 port_attr_info->trans);
+	err = dpaa2_switch_port_attr_set(netdev, port_attr_info->attr);
 
 	port_attr_info->handled = true;
 	return notifier_from_errno(err);