[PATCH net-next] bonding: show master index when dumping slave info

[PATCH net-next] bonding: show master index when dumping slave info

[Hangbin Liu]

Currently, there is no straightforward way to obtain the master/slave
relationship via netlink. Users have to retrieve all slaves through sysfs
to determine these relationships.

To address this, we can either list all slaves under the bond interface
or display the master index in each slave. Since the number of slaves could
be quite large (e.g., 100+), it is more efficient to show the master
information in the slave entry.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 drivers/net/bonding/bond_netlink.c | 4 ++++
 include/uapi/linux/if_link.h       | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
index 286f11c517f7..ff3f11674a8b 100644
--- a/drivers/net/bonding/bond_netlink.c
+++ b/drivers/net/bonding/bond_netlink.c
@@ -29,6 +29,7 @@ static size_t bond_get_slave_size(const struct net_device *bond_dev,
 		nla_total_size(sizeof(u16)) +	/* IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE */
 		nla_total_size(sizeof(s32)) +	/* IFLA_BOND_SLAVE_PRIO */
 		nla_total_size(sizeof(u16)) +	/* IFLA_BOND_SLAVE_ACTOR_PORT_PRIO */
+		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_SLAVE_MASTER */
 		0;
 }
 
@@ -38,6 +39,9 @@ static int bond_fill_slave_info(struct sk_buff *skb,
 {
 	struct slave *slave = bond_slave_get_rtnl(slave_dev);
 
+	if (nla_put_u32(skb, IFLA_BOND_SLAVE_MASTER, bond_dev->ifindex))
+		goto nla_put_failure;
+
 	if (nla_put_u8(skb, IFLA_BOND_SLAVE_STATE, bond_slave_state(slave)))
 		goto nla_put_failure;
 
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 3b491d96e52e..bad41a1807f7 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -1567,6 +1567,7 @@ enum {
 	IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE,
 	IFLA_BOND_SLAVE_PRIO,
 	IFLA_BOND_SLAVE_ACTOR_PORT_PRIO,
+	IFLA_BOND_SLAVE_MASTER,
 	__IFLA_BOND_SLAVE_MAX,
 };
 
-- 
2.50.1

[PATCH iproute2-next] bond: slave: print master name

[Hangbin Liu]

Add a new attribute to display the name of the master interface for
each slave.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 ip/iplink_bond_slave.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/ip/iplink_bond_slave.c b/ip/iplink_bond_slave.c
index c88100e248dd..55deaadf5fe2 100644
--- a/ip/iplink_bond_slave.c
+++ b/ip/iplink_bond_slave.c
@@ -92,6 +92,17 @@ static void bond_slave_print_opt(struct link_util *lu, FILE *f, struct rtattr *t
 	if (!tb)
 		return;
 
+	if (tb[IFLA_BOND_SLAVE_MASTER]) {
+		unsigned int ifindex = rta_getattr_u32(tb[IFLA_BOND_SLAVE_MASTER]);
+
+		if (ifindex) {
+			print_string(PRINT_ANY,
+				     "master",
+				     "master %s ",
+				     ll_index_to_name(ifindex));
+		}
+	}
+
 	if (tb[IFLA_BOND_SLAVE_STATE])
 		print_slave_state(f, tb[IFLA_BOND_SLAVE_STATE]);
 
-- 
2.50.1

Re: [PATCH iproute2-next] bond: slave: print master name

[Stephen Hemminger]

On Fri, 17 Oct 2025 03:05:09 +0000
Hangbin Liu <liuhangbin@gmail.com> wrote:

> diff --git a/ip/iplink_bond_slave.c b/ip/iplink_bond_slave.c
> index c88100e248dd..55deaadf5fe2 100644
> --- a/ip/iplink_bond_slave.c
> +++ b/ip/iplink_bond_slave.c
> @@ -92,6 +92,17 @@ static void bond_slave_print_opt(struct link_util *lu, FILE *f, struct rtattr *t
>  	if (!tb)
>  		return;
>  
> +	if (tb[IFLA_BOND_SLAVE_MASTER]) {
> +		unsigned int ifindex = rta_getattr_u32(tb[IFLA_BOND_SLAVE_MASTER]);
> +
> +		if (ifindex) {
> +			print_string(PRINT_ANY,
> +				     "master",
> +				     "master %s ",
> +				     ll_index_to_name(ifindex));
> +		}
> +	}

You should use print_color_string(PRINT_ANY, COLOR_IFNAME, ...) here

Re: [PATCH net-next] bonding: show master index when dumping slave info

[Nikolay Aleksandrov]

On 10/17/25 06:03, Hangbin Liu wrote:
> Currently, there is no straightforward way to obtain the master/slave
> relationship via netlink. Users have to retrieve all slaves through sysfs
> to determine these relationships.
> 

How about IFLA_MASTER? Why not use that?

> To address this, we can either list all slaves under the bond interface
> or display the master index in each slave. Since the number of slaves could
> be quite large (e.g., 100+), it is more efficient to show the master
> information in the slave entry.
> 
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---
>  drivers/net/bonding/bond_netlink.c | 4 ++++
>  include/uapi/linux/if_link.h       | 1 +
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
> index 286f11c517f7..ff3f11674a8b 100644
> --- a/drivers/net/bonding/bond_netlink.c
> +++ b/drivers/net/bonding/bond_netlink.c
> @@ -29,6 +29,7 @@ static size_t bond_get_slave_size(const struct net_device *bond_dev,
>  		nla_total_size(sizeof(u16)) +	/* IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE */
>  		nla_total_size(sizeof(s32)) +	/* IFLA_BOND_SLAVE_PRIO */
>  		nla_total_size(sizeof(u16)) +	/* IFLA_BOND_SLAVE_ACTOR_PORT_PRIO */
> +		nla_total_size(sizeof(u32)) +	/* IFLA_BOND_SLAVE_MASTER */
>  		0;
>  }
>  
> @@ -38,6 +39,9 @@ static int bond_fill_slave_info(struct sk_buff *skb,
>  {
>  	struct slave *slave = bond_slave_get_rtnl(slave_dev);
>  
> +	if (nla_put_u32(skb, IFLA_BOND_SLAVE_MASTER, bond_dev->ifindex))
> +		goto nla_put_failure;
> +
>  	if (nla_put_u8(skb, IFLA_BOND_SLAVE_STATE, bond_slave_state(slave)))
>  		goto nla_put_failure;
>  
> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
> index 3b491d96e52e..bad41a1807f7 100644
> --- a/include/uapi/linux/if_link.h
> +++ b/include/uapi/linux/if_link.h
> @@ -1567,6 +1567,7 @@ enum {
>  	IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE,
>  	IFLA_BOND_SLAVE_PRIO,
>  	IFLA_BOND_SLAVE_ACTOR_PORT_PRIO,
> +	IFLA_BOND_SLAVE_MASTER,
>  	__IFLA_BOND_SLAVE_MAX,
>  };
>  

Re: [PATCH net-next] bonding: show master index when dumping slave info

[Hangbin Liu]

On Fri, Oct 17, 2025 at 09:10:09AM +0300, Nikolay Aleksandrov wrote:
> On 10/17/25 06:03, Hangbin Liu wrote:
> > Currently, there is no straightforward way to obtain the master/slave
> > relationship via netlink. Users have to retrieve all slaves through sysfs
> > to determine these relationships.
> > 
> 
> How about IFLA_MASTER? Why not use that?

Ah, I didn't notice this. We can show the master info directly with this...

# ip link show dummy0
3: dummy0: <BROADCAST,NOARP,SLAVE,UP,LOWER_UP> mtu 1500 qdisc noqueue master bond0 ...

Please ignore this patch.

Thanks
Hangbin

Re: [PATCH net-next] bonding: show master index when dumping slave info

[Jiri Pirko]

Fri, Oct 17, 2025 at 08:10:09AM +0200, razor@blackwall.org wrote:
>On 10/17/25 06:03, Hangbin Liu wrote:
>> Currently, there is no straightforward way to obtain the master/slave
>> relationship via netlink. Users have to retrieve all slaves through sysfs
>> to determine these relationships.
>> 
>
>How about IFLA_MASTER? Why not use that?

It's been there for a decade. Plus is, it exposes master for all
slave-master devices. Odd that you missed it.

Re: [PATCH net-next] bonding: show master index when dumping slave info

[Hangbin Liu]

On Fri, Oct 17, 2025 at 11:56:55AM +0200, Jiri Pirko wrote:
> Fri, Oct 17, 2025 at 08:10:09AM +0200, razor@blackwall.org wrote:
> >On 10/17/25 06:03, Hangbin Liu wrote:
> >> Currently, there is no straightforward way to obtain the master/slave
> >> relationship via netlink. Users have to retrieve all slaves through sysfs
> >> to determine these relationships.
> >> 
> >
> >How about IFLA_MASTER? Why not use that?
> 
> It's been there for a decade. Plus is, it exposes master for all
> slave-master devices. Odd that you missed it.

Once, I wanted to find the slaves from a master interface but couldn’t. So I
added it to my to-do list. Later, I noticed that the master information was
already available in the slave, but I forgot about it after long time.
Recently, when I reviewed my to-do list, I realized that printing all slaves
from the master interface seemed impractical. So I tried to list the master
information in the slave again — and forgot about IFLA_MASTER...

Hangbin