[PATCH net-next 02/18] switchdev: flesh out get/set attr ops

[sfeldma@gmail.com]

From: Scott Feldman <sfeldma@gmail.com>

Add the basic algorithms for get/set attr ops.  Use the same recusive algo to
walk lower devs we've used for STP updates, for example.  For get, compare attr
value for each lower dev and only return success if attr values match across
all lower devs.  For sets, set the same attr value for all lower devs.  If
something goes wrong on one of the lower devs, revert all back to previous attr
value.

If lower dev recusion isn't desired, allow a flag SWDEV_ATTR_F_NO_RECURSE to
indicate get/set only work on port (lowest) device.

On set, allow a flag SWDEV_ATTR_F_NO_RECOVER to turn off automatic err
recovery.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
---
 include/net/switchdev.h   |    4 +++
 net/switchdev/switchdev.c |   71 +++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/include/net/switchdev.h b/include/net/switchdev.h
index 7b72a4f..dcf0cb7 100644
--- a/include/net/switchdev.h
+++ b/include/net/switchdev.h
@@ -18,8 +18,12 @@ enum swdev_attr_id {
 	SWDEV_ATTR_UNDEFINED,
 };
 
+#define SWDEV_ATTR_F_NO_RECURSE		BIT(0)
+#define SWDEV_ATTR_F_NO_RECOVER		BIT(1)
+
 struct swdev_attr {
 	enum swdev_attr_id attr;
+	u32 flags;
 };
 
 struct fib_info;
diff --git a/net/switchdev/switchdev.c b/net/switchdev/switchdev.c
index a894fa5..f3cac92 100644
--- a/net/switchdev/switchdev.c
+++ b/net/switchdev/switchdev.c
@@ -44,10 +44,67 @@ EXPORT_SYMBOL_GPL(netdev_switch_parent_id_get);
  */
 int swdev_port_attr_get(struct net_device *dev, struct swdev_attr *attr)
 {
-	return -EOPNOTSUPP;
+	const struct swdev_ops *ops = dev->swdev_ops;
+	struct net_device *lower_dev;
+	struct list_head *iter;
+	struct swdev_attr first = {
+		.attr = SWDEV_ATTR_UNDEFINED
+	};
+	int err = -EOPNOTSUPP;
+
+	if (ops && ops->swdev_port_attr_get)
+		return ops->swdev_port_attr_get(dev, attr);
+
+	if (attr->flags & SWDEV_ATTR_F_NO_RECURSE)
+		return err;
+
+	/* Switch device port(s) may be stacked under
+	 * bond/team/vlan dev, so recurse down to get attr on
+	 * each port.  Return -ENODATA if attr values don't
+	 * compare across ports.
+	 */
+
+	netdev_for_each_lower_dev(dev, lower_dev, iter) {
+		err = swdev_port_attr_get(lower_dev, attr);
+		if (err)
+			break;
+		if (first.attr == SWDEV_ATTR_UNDEFINED)
+			first = *attr;
+		else if (memcmp(&first, attr, sizeof(*attr)))
+			return -ENODATA;
+	}
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(swdev_port_attr_get);
 
+static int _swdev_port_attr_set(struct net_device *dev, struct swdev_attr *attr)
+{
+	const struct swdev_ops *ops = dev->swdev_ops;
+	struct net_device *lower_dev;
+	struct list_head *iter;
+	int err = -EOPNOTSUPP;
+
+	if (ops && ops->swdev_port_attr_set)
+		return ops->swdev_port_attr_set(dev, attr);
+
+	if (attr->flags & SWDEV_ATTR_F_NO_RECURSE)
+		return err;
+
+	/* Switch device port(s) may be stacked under
+	 * bond/team/vlan dev, so recurse down to set attr on
+	 * each port.
+	 */
+
+	netdev_for_each_lower_dev(dev, lower_dev, iter) {
+		err = _swdev_port_attr_set(lower_dev, attr);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
 /**
  *	swdev_port_attr_set - Set port attribute
  *
@@ -56,7 +113,17 @@ EXPORT_SYMBOL_GPL(swdev_port_attr_get);
  */
 int swdev_port_attr_set(struct net_device *dev, struct swdev_attr *attr)
 {
-	return -EOPNOTSUPP;
+	struct swdev_attr prev = *attr;
+	int err, get_err;
+
+	get_err = swdev_port_attr_get(dev, &prev);
+
+	err = _swdev_port_attr_set(dev, attr);
+	if (err && !get_err && !(attr->flags & SWDEV_ATTR_F_NO_RECOVER))
+		/* Some err on set: revert to previous value */
+		_swdev_port_attr_set(dev, &prev);
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(swdev_port_attr_set);
 
-- 
1.7.10.4