Subject: Re: [PATCH net-next 3/8] bonding: add downdelay netlink support

From: Jay Vosburgh <[email-masked]>
Date: Thu, 07 Nov 2013 09:05:10 -0800

Scott Feldman <[email-masked]> wrote:

>Add IFLA_BOND_DOWNDELAY to allow get/set of bonding parameter
>downdelay via netlink.
>
>Signed-off-by: Scott Feldman <[email-masked]>
>---
> drivers/net/bonding/bond_netlink.c |   12 +++++++++++
> drivers/net/bonding/bond_options.c |   29 +++++++++++++++++++++++++++
> drivers/net/bonding/bond_sysfs.c   |   38 +++++++++---------------------------
> drivers/net/bonding/bonding.h      |    1 +
> include/uapi/linux/if_link.h       |    1 +
> 5 files changed, 52 insertions(+), 29 deletions(-)
>
>diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
>index 9ba5431..e684713 100644
>--- a/drivers/net/bonding/bond_netlink.c
>+++ b/drivers/net/bonding/bond_netlink.c
>@@ -26,6 +26,7 @@ static const struct nla_policy bond_policy[IFLA_BOND_MAX + 1] = {
> 	[IFLA_BOND_ACTIVE_SLAVE]	= { .type = NLA_U32 },
> 	[IFLA_BOND_MIIMON]		= { .type = NLA_U32 },
> 	[IFLA_BOND_UPDELAY]		= { .type = NLA_U32 },
>+	[IFLA_BOND_DOWNDELAY]		= { .type = NLA_U32 },
> };
>
> static int bond_validate(struct nlattr *tb[], struct nlattr *data[])
>@@ -85,6 +86,13 @@ static int bond_changelink(struct net_device *bond_dev,
> 		if (err)
> 			return err;
> 	}
>+	if (data[IFLA_BOND_DOWNDELAY]) {
>+		int downdelay = nla_get_u32(data[IFLA_BOND_DOWNDELAY]);
>+
>+		err = bond_option_downdelay_set(bond, downdelay);
>+		if (err)
>+			return err;
>+	}
> 	return 0;
> }
>
>@@ -106,6 +114,7 @@ static size_t bond_get_size(const struct net_device *bond_dev)
> 		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_ACTIVE_SLAVE */
> 		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_MIIMON */
> 		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_UPDELAY */
>+		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_DOWNDELAY */
> 		0;
> }
>
>@@ -128,6 +137,9 @@ static int bond_fill_info(struct sk_buff *skb,
> 	if (nla_put_u32(skb, IFLA_BOND_UPDELAY, bond->params.updelay))
> 		goto nla_put_failure;
>
>+	if (nla_put_u32(skb, IFLA_BOND_DOWNDELAY, bond->params.downdelay))
>+		goto nla_put_failure;
>+
> 	return 0;
>
> nla_put_failure:
>diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
>index c0fea66..738be5f 100644
>--- a/drivers/net/bonding/bond_options.c
>+++ b/drivers/net/bonding/bond_options.c
>@@ -211,3 +211,32 @@ int bond_option_updelay_set(struct bonding *bond, int updelay)
>
> 	return 0;
> }
>+
>+int bond_option_downdelay_set(struct bonding *bond, int downdelay)
>+{
>+	if (!(bond->params.miimon)) {
>+		pr_err("%s: Unable to set down delay as MII monitoring is disabled\n", bond->dev->name);
>+		return -EPERM;
>+	}

	I would argue that it is better to permit this option to be set
at any time, regardless of whether miimon is enabled or not.  This
removes an ordering constraint and makes things generally easier to deal
with.  Setting the option has no effect if miimon is not set, but that's
ok.

	My comment here would also apply to other options that are
"secondary," in the sense that they affect the behavior of other options
or modes, e.g., updelay, arp_validate (in another path of this series),
arp_ip_targets, etc.

	I'm aware that this is simply duplicating the existing behavior
of the sysfs API, but I'd be in favor of changing that, too.  These
limitations are a holdover from the module paramters days, and should
have been made more flexible a long time ago.

	-J

>+
>+	if (downdelay < 0) {
>+		pr_err("%s: Invalid down delay value %d not in range %d-%d; rejected.\n",
>+		       bond->dev->name, downdelay, 0, INT_MAX);
>+		return -EINVAL;
>+	} else {
>+		if ((downdelay % bond->params.miimon) != 0) {
>+			pr_warn("%s: Warning: down delay (%d) is not a multiple of miimon (%d), delay rounded to %d ms\n",
>+				bond->dev->name, downdelay,
>+				bond->params.miimon,
>+				(downdelay / bond->params.miimon) *
>+				bond->params.miimon);
>+		}
>+		bond->params.downdelay = downdelay / bond->params.miimon;
>+		pr_info("%s: Setting down delay to %d.\n",
>+			bond->dev->name,
>+			bond->params.downdelay * bond->params.miimon);
>+
>+	}
>+
>+	return 0;
>+}
>diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
>index 1125bef..41a62ac 100644
>--- a/drivers/net/bonding/bond_sysfs.c
>+++ b/drivers/net/bonding/bond_sysfs.c
>@@ -706,42 +706,22 @@ static ssize_t bonding_store_downdelay(struct device *d,
> 				       struct device_attribute *attr,
> 				       const char *buf, size_t count)
> {
>-	int new_value, ret = count;
>+	int new_value, ret;
> 	struct bonding *bond = to_bond(d);
>
>-	if (!(bond->params.miimon)) {
>-		pr_err("%s: Unable to set down delay as MII monitoring is disabled\n",
>-		       bond->dev->name);
>-		ret = -EPERM;
>-		goto out;
>-	}
>-
> 	if (sscanf(buf, "%d", &new_value) != 1) {
> 		pr_err("%s: no down delay value specified.\n", bond->dev->name);
>-		ret = -EINVAL;
>-		goto out;
>+		return -EINVAL;
> 	}
>-	if (new_value < 0) {
>-		pr_err("%s: Invalid down delay value %d not in range %d-%d; rejected.\n",
>-		       bond->dev->name, new_value, 0, INT_MAX);
>-		ret = -EINVAL;
>-		goto out;
>-	} else {
>-		if ((new_value % bond->params.miimon) != 0) {
>-			pr_warning("%s: Warning: down delay (%d) is not a multiple of miimon (%d), delay rounded to %d ms\n",
>-				   bond->dev->name, new_value,
>-				   bond->params.miimon,
>-				   (new_value / bond->params.miimon) *
>-				   bond->params.miimon);
>-		}
>-		bond->params.downdelay = new_value / bond->params.miimon;
>-		pr_info("%s: Setting down delay to %d.\n",
>-			bond->dev->name,
>-			bond->params.downdelay * bond->params.miimon);
>
>-	}
>+	if (!rtnl_trylock())
>+		return restart_syscall();
>
>-out:
>+	ret = bond_option_downdelay_set(bond, new_value);
>+	if (!ret)
>+		ret = count;
>+
>+	rtnl_unlock();
> 	return ret;
> }
> static DEVICE_ATTR(downdelay, S_IRUGO | S_IWUSR,
>diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
>index 408e6c2..40987f3 100644
>--- a/drivers/net/bonding/bonding.h
>+++ b/drivers/net/bonding/bonding.h
>@@ -430,6 +430,7 @@ int bond_option_mode_set(struct bonding *bond, int mode);
> int bond_option_active_slave_set(struct bonding *bond, struct net_device *slave_dev);
> int bond_option_miimon_set(struct bonding *bond, int miimon);
> int bond_option_updelay_set(struct bonding *bond, int updelay);
>+int bond_option_downdelay_set(struct bonding *bond, int downdelay);
> struct net_device *bond_option_active_slave_get_rcu(struct bonding *bond);
> struct net_device *bond_option_active_slave_get(struct bonding *bond);
>
>diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
>index 361414e..a372831 100644
>--- a/include/uapi/linux/if_link.h
>+++ b/include/uapi/linux/if_link.h
>@@ -333,6 +333,7 @@ enum {
> 	IFLA_BOND_ACTIVE_SLAVE,
> 	IFLA_BOND_MIIMON,
> 	IFLA_BOND_UPDELAY,
>+	IFLA_BOND_DOWNDELAY,
> 	__IFLA_BOND_MAX,
> };
>
>

---
	-Jay Vosburgh, IBM Linux Technology Center, [email-masked]