Date:   Wed, 15 Jun 2022 13:44:57 -0400
From:   Jonathan Toppins <jtoppins@...hat.com>
To:     Hangbin Liu <liuhangbin@...il.com>, netdev@...r.kernel.org
Cc:     Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...il.com>
Subject: Re: [PATCHv2 net-next] Bonding: add per-port priority for failover
 re-selection

On 6/14/22 23:29, Hangbin Liu wrote:
> Add per port priority support for bonding active slave re-selection during
> failover. A higher number means higher priority in selection. The primary
> slave still has the highest priority. This option also follows the
> primary_reselect rules.
> 
> This option could only be configured via netlink.
> 
> v2: using the extant bonding options management stuff instead setting
> slave prio in bond_slave_changelink() directly.
> 
> Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
> ---
>   Documentation/networking/bonding.rst | 11 +++++
>   drivers/net/bonding/bond_main.c      | 27 +++++++++++
>   drivers/net/bonding/bond_netlink.c   | 19 ++++++++
>   drivers/net/bonding/bond_options.c   | 67 ++++++++++++++++++++++++++++
>   include/net/bond_options.h           |  1 +
>   include/net/bonding.h                |  1 +
>   include/uapi/linux/if_link.h         |  1 +
>   tools/include/uapi/linux/if_link.h   |  1 +
>   8 files changed, 128 insertions(+)
> 
> diff --git a/Documentation/networking/bonding.rst b/Documentation/networking/bonding.rst
> index 43be3782e5df..53a18ff7cf23 100644
> --- a/Documentation/networking/bonding.rst
> +++ b/Documentation/networking/bonding.rst
> @@ -780,6 +780,17 @@ peer_notif_delay
>   	value is 0 which means to match the value of the link monitor
>   	interval.
>   
> +prio
> +	Slave priority. A higher number means higher priority.
> +	The primary slave has the highest priority. This option also
> +	follows the primary_reselect rules.
> +
> +	This option could only be configured via netlink, and is only valid
> +	for active-backup(1), balance-tlb (5) and balance-alb (6) mode.
> +	The valid value range is a signed 32 bit integer.
> +
> +	The default value is 0.

Why is this a signed 32 bit number? Why not a u8, it would seem 256 
[255,0] options is more than enough to select from. Is there a specific 
reason it needs to be an s32?

If the reason for selecting a signed value is so that the default 
priority could be in the middle of the range, why not just set the 
default to be 128, assuming u8 is wide enough?

> +
>   primary
>   
>   	A string (eth0, eth2, etc) specifying which slave is the
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 3d427183ec8e..3415a0feea07 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1026,12 +1026,38 @@ static void bond_do_fail_over_mac(struct bonding *bond,
>   
>   }
>   
> +/**
> + * bond_choose_primary_or_current - select the primary or high priority slave
> + * @bond: our bonding struct
> + *
> + * - Check if there is a primary link. If the primary link was set and is up,
> + *   go on and do link reselection.
> + *
> + * - If primary link is not set or down, find the highest priority link.
> + *   If the highest priority link is not current slave, set it as primary
> + *   link and do link reselection.
> + */
>   static struct slave *bond_choose_primary_or_current(struct bonding *bond)
>   {
>   	struct slave *prim = rtnl_dereference(bond->primary_slave);
>   	struct slave *curr = rtnl_dereference(bond->curr_active_slave);
> +	struct slave *slave, *hprio = NULL;
> +	struct list_head *iter;
>   
>   	if (!prim || prim->link != BOND_LINK_UP) {
> +		bond_for_each_slave(bond, slave, iter) {
> +			if (slave->link == BOND_LINK_UP) {
> +				hprio = hprio ?: slave;
> +				if (slave->prio > hprio->prio)
> +					hprio = slave;
> +			}
> +		}
> +
> +		if (hprio && hprio != curr) {
> +			prim = hprio;
> +			goto link_reselect;
> +		}
> +
>   		if (!curr || curr->link != BOND_LINK_UP)
>   			return NULL;
>   		return curr;
> @@ -1042,6 +1068,7 @@ static struct slave *bond_choose_primary_or_current(struct bonding *bond)
>   		return prim;
>   	}
>   
> +link_reselect:
>   	if (!curr || curr->link != BOND_LINK_UP)
>   		return prim;
>   
> diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
> index 5a6f44455b95..41b3244747fa 100644
> --- a/drivers/net/bonding/bond_netlink.c
> +++ b/drivers/net/bonding/bond_netlink.c
> @@ -27,6 +27,7 @@ static size_t bond_get_slave_size(const struct net_device *bond_dev,
>   		nla_total_size(sizeof(u16)) +	/* IFLA_BOND_SLAVE_AD_AGGREGATOR_ID */
>   		nla_total_size(sizeof(u8)) +	/* IFLA_BOND_SLAVE_AD_ACTOR_OPER_PORT_STATE */
>   		nla_total_size(sizeof(u16)) +	/* IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE */
> +		nla_total_size(sizeof(s32)) +	/* IFLA_BOND_SLAVE_PRIO */
>   		0;
>   }
>   
> @@ -53,6 +54,9 @@ static int bond_fill_slave_info(struct sk_buff *skb,
>   	if (nla_put_u16(skb, IFLA_BOND_SLAVE_QUEUE_ID, slave->queue_id))
>   		goto nla_put_failure;
>   
> +	if (nla_put_s32(skb, IFLA_BOND_SLAVE_PRIO, slave->prio))
> +		goto nla_put_failure;
> +
>   	if (BOND_MODE(slave->bond) == BOND_MODE_8023AD) {
>   		const struct aggregator *agg;
>   		const struct port *ad_port;
> @@ -117,6 +121,7 @@ static const struct nla_policy bond_policy[IFLA_BOND_MAX + 1] = {
>   
>   static const struct nla_policy bond_slave_policy[IFLA_BOND_SLAVE_MAX + 1] = {
>   	[IFLA_BOND_SLAVE_QUEUE_ID]	= { .type = NLA_U16 },
> +	[IFLA_BOND_SLAVE_PRIO]		= { .type = NLA_S32 },
>   };
>   
>   static int bond_validate(struct nlattr *tb[], struct nlattr *data[],
> @@ -157,6 +162,20 @@ static int bond_slave_changelink(struct net_device *bond_dev,
>   			return err;
>   	}
>   
> +	if (data[IFLA_BOND_SLAVE_PRIO]) { > +		int prio = nla_get_s32(data[IFLA_BOND_SLAVE_PRIO]);
> +		char prio_str[IFNAMSIZ + 7];
> +
> +		/* prio option setting expects slave_name:prio */
> +		snprintf(prio_str, sizeof(prio_str), "%s:%d\n",
> +			 slave_dev->name, prio);
> +
> +		bond_opt_initstr(&newval, prio_str);

It might be less code and a little cleaner to extend struct 
bond_opt_value with a slave pointer.

	struct bond_opt_value {
		char *string;
		u64 value;
		u32 flags;
		union {
			char cextra[BOND_OPT_EXTRA_MAXLEN];
			struct net_device *slave_dev;
		} extra;
	};

Then modify __bond_opt_init to set the slave pointer, basically a set of 
bond_opt_slave_init{} macros. This would remove the need to parse the 
slave interface name in the set function. Setting .flags = 
BOND_OPTFLAG_RAWVAL (already done I see) in the option definition to 
avoid bond_opt_parse() from loosing our extra information by pointing to 
a .values table entry. Now in the option specific set function we can 
just find the slave entry and set the value, no more string parsing code 
needed.

> +		err = __bond_opt_set(bond, BOND_OPT_PRIO, &newval);

I think this patch series needs to be rebased onto latest 
net-next/master as a patch series I sent added two extra parameter list 
arguments to __bond_opt_set().

   2bff369b2354 bonding: netlink error message support for options

Considering my comments above about extending bond_opt_value, I might 
look as sending a fixup patch to remove all the parameter list additions 
and hide the netlink extack pointer in bond_opt_value.

> +		if (err)
> +			return err;
> +	}
> +
>   	return 0;
>   }
>   
> diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
> index 96eef19cffc4..bac3858825b3 100644
> --- a/drivers/net/bonding/bond_options.c
> +++ b/drivers/net/bonding/bond_options.c
> @@ -40,6 +40,8 @@ static int bond_option_arp_validate_set(struct bonding *bond,
>   					const struct bond_opt_value *newval);
>   static int bond_option_arp_all_targets_set(struct bonding *bond,
>   					   const struct bond_opt_value *newval);
> +static int bond_option_prio_set(struct bonding *bond,
> +				const struct bond_opt_value *newval);
>   static int bond_option_primary_set(struct bonding *bond,
>   				   const struct bond_opt_value *newval);
>   static int bond_option_primary_reselect_set(struct bonding *bond,
> @@ -365,6 +367,16 @@ static const struct bond_option bond_opts[BOND_OPT_LAST] = {
>   		.values = bond_intmax_tbl,
>   		.set = bond_option_miimon_set
>   	},
> +	[BOND_OPT_PRIO] = {
> +		.id = BOND_OPT_PRIO,
> +		.name = "prio",
> +		.desc = "Link priority for failover re-selection",
> +		.flags = BOND_OPTFLAG_RAWVAL,
> +		.unsuppmodes = BOND_MODE_ALL_EX(BIT(BOND_MODE_ACTIVEBACKUP) |
> +						BIT(BOND_MODE_TLB) |
> +						BIT(BOND_MODE_ALB)),
> +		.set = bond_option_prio_set
> +	},
>   	[BOND_OPT_PRIMARY] = {
>   		.id = BOND_OPT_PRIMARY,
>   		.name = "primary",
> @@ -1306,6 +1318,61 @@ static int bond_option_missed_max_set(struct bonding *bond,
>   	return 0;
>   }
>   
> +static int bond_option_prio_set(struct bonding *bond,
> +				const struct bond_opt_value *newval)
> +{
> +	struct slave *slave, *update_slave;
> +	struct net_device *sdev;
> +	struct list_head *iter;
> +	char *delim;
> +	int ret = 0;
> +	int prio;

Priorities are only considered if there is no primary set, correct? 
Would you not want to issue a netdev_warn here noting the fact that this 
will be ignored if the bond device has a primary set? Much like how 
other options issue warnings, or in miimon's case turn off arp monitor, 
when other configuration influence the effectiveness of the setting?

> +
> +	/* delim will point to prio if successful */
> +	delim = strchr(newval->string, ':');
> +	if (!delim)
> +		goto err_no_cmd;
> +
> +	/* Terminate string that points to device name and bump it
> +	 * up one, so we can read the prio there.
> +	 */
> +	*delim = '\0';
> +	if (sscanf(++delim, "%d\n", &prio) != 1)
> +		goto err_no_cmd;
> +
> +	/* Valid ifname */
> +	if (!dev_valid_name(newval->string))
> +		goto err_no_cmd;
> +
> +	/* Get the pointer to that interface if it exists */
> +	sdev = __dev_get_by_name(dev_net(bond->dev), newval->string);
> +	if (!sdev)
> +		goto err_no_cmd;
> +
> +	update_slave = NULL;
> +	bond_for_each_slave(bond, slave, iter) {
> +		if (sdev == slave->dev)
> +			update_slave = slave;
> +	}
> +
> +	if (!update_slave)
> +		goto err_no_cmd;
> +
> +	/* Actually set the prio for the slave */
> +	update_slave->prio = prio;
> +
> +	/* Do reselect after prio update */
> +	bond_select_active_slave(bond);
> +
> +out:
> +	return ret;
> +
> +err_no_cmd:
> +	netdev_dbg(bond->dev, "invalid input for slave prio set\n");
> +	ret = -EPERM;
> +	goto out;
> +}
> +
>   static int bond_option_primary_set(struct bonding *bond,
>   				   const struct bond_opt_value *newval)
>   {
> diff --git a/include/net/bond_options.h b/include/net/bond_options.h
> index 1618b76f4903..569808933094 100644
> --- a/include/net/bond_options.h
> +++ b/include/net/bond_options.h
> @@ -67,6 +67,7 @@ enum {
>   	BOND_OPT_LACP_ACTIVE,
>   	BOND_OPT_MISSED_MAX,
>   	BOND_OPT_NS_TARGETS,
> +	BOND_OPT_PRIO,
>   	BOND_OPT_LAST
>   };
>   
> diff --git a/include/net/bonding.h b/include/net/bonding.h
> index cb904d356e31..6e78d657aa05 100644
> --- a/include/net/bonding.h
> +++ b/include/net/bonding.h
> @@ -178,6 +178,7 @@ struct slave {
>   	u32    speed;
>   	u16    queue_id;
>   	u8     perm_hwaddr[MAX_ADDR_LEN];
> +	int    prio;
>   	struct ad_slave_info *ad_info;
>   	struct tlb_slave_info tlb_info;
>   #ifdef CONFIG_NET_POLL_CONTROLLER
> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
> index 5f58dcfe2787..e36d9d2c65a7 100644
> --- a/include/uapi/linux/if_link.h
> +++ b/include/uapi/linux/if_link.h
> @@ -963,6 +963,7 @@ enum {
>   	IFLA_BOND_SLAVE_AD_AGGREGATOR_ID,
>   	IFLA_BOND_SLAVE_AD_ACTOR_OPER_PORT_STATE,
>   	IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE,
> +	IFLA_BOND_SLAVE_PRIO,
>   	__IFLA_BOND_SLAVE_MAX,
>   };
>   
> diff --git a/tools/include/uapi/linux/if_link.h b/tools/include/uapi/linux/if_link.h
> index b339bf2196ca..0242f31e339c 100644
> --- a/tools/include/uapi/linux/if_link.h
> +++ b/tools/include/uapi/linux/if_link.h
> @@ -890,6 +890,7 @@ enum {
>   	IFLA_BOND_SLAVE_AD_AGGREGATOR_ID,
>   	IFLA_BOND_SLAVE_AD_ACTOR_OPER_PORT_STATE,
>   	IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE,
> +	IFLA_BOND_SLAVE_PRIO,
>   	__IFLA_BOND_SLAVE_MAX,
>   };
>   

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