| Message ID | 20221111161729.915233-1-linux@rasmusvillemoes.dk (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: dsa: use NET_NAME_PREDICTABLE for user ports with name given in DT | expand |
> diff --git a/net/dsa/slave.c b/net/dsa/slave.c > index a9fde48cffd4..dfefcc4a9ccf 100644 > --- a/net/dsa/slave.c > +++ b/net/dsa/slave.c > @@ -2374,16 +2374,25 @@ int dsa_slave_create(struct dsa_port *port) > { > struct net_device *master = dsa_port_to_master(port); > struct dsa_switch *ds = port->ds; > - const char *name = port->name; > struct net_device *slave_dev; > struct dsa_slave_priv *p; > + const char *name; > + int assign_type; > int ret; > > if (!ds->num_tx_queues) > ds->num_tx_queues = 1; > > + if (port->name) { > + name = port->name; > + assign_type = NET_NAME_PREDICTABLE; > + } else { > + name = "eth%d"; > + assign_type = NET_NAME_UNKNOWN; > + } I know it is a change in behaviour, but it seems like NET_NAME_ENUM should be used, not NET_NAME_UNKNOWN. alloc_etherdev_mqs() uses NET_NAME_ENUM. https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/netdevice.h#L42 says that NET_NAME_UNKNOWN does not get passed to user space, but i assume NET_NAME_ENUM does. So maybe changing it would be an ABI change? Humm, i don't know what the right thing is... Andrew
On 11/11/2022 18.10, Andrew Lunn wrote: >> diff --git a/net/dsa/slave.c b/net/dsa/slave.c >> index a9fde48cffd4..dfefcc4a9ccf 100644 >> --- a/net/dsa/slave.c >> +++ b/net/dsa/slave.c >> @@ -2374,16 +2374,25 @@ int dsa_slave_create(struct dsa_port *port) >> { >> struct net_device *master = dsa_port_to_master(port); >> struct dsa_switch *ds = port->ds; >> - const char *name = port->name; >> struct net_device *slave_dev; >> struct dsa_slave_priv *p; >> + const char *name; >> + int assign_type; >> int ret; >> >> if (!ds->num_tx_queues) >> ds->num_tx_queues = 1; >> >> + if (port->name) { >> + name = port->name; >> + assign_type = NET_NAME_PREDICTABLE; >> + } else { >> + name = "eth%d"; >> + assign_type = NET_NAME_UNKNOWN; >> + } > > I know it is a change in behaviour, but it seems like NET_NAME_ENUM > should be used, not NET_NAME_UNKNOWN. alloc_etherdev_mqs() uses > NET_NAME_ENUM. I don't really have any strong opinion on the case where we fall back to eth%d, as its not relevant to any board I've worked on. > https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/netdevice.h#L42 > says that NET_NAME_UNKNOWN does not get passed to user space, but i > assume NET_NAME_ENUM does. So maybe changing it would be an ABI > change? Well, the name_assign_type ABI is kind of silly. I mean, userspace knows that when one gets EINVAL trying to read the value, that really means that the value is NET_NAME_UNKNOWN. But I won't propose changing that. However, what I do propose here is obviously already an ABI change; I _want_ to expose more proper information in the case where the port has a label, and just kept the NET_NAME_UNKNOWN for the eth%d case to make the minimal change. But if people want to change that to NET_NAME_ENUM while we're here, I can certainly do that. I can't think of any real scenario where NET_NAME_ENUM would be treated differently than NET_NAME_UNKNOWN - in both cases, userspace don't know that the name can be trusted to be predictable. Rasmus
On Sun, 13 Nov 2022 21:03:52 +0100 Rasmus Villemoes wrote: > > I know it is a change in behaviour, but it seems like NET_NAME_ENUM > > should be used, not NET_NAME_UNKNOWN. alloc_etherdev_mqs() uses > > NET_NAME_ENUM. > > I don't really have any strong opinion on the case where we fall back to > eth%d, as its not relevant to any board I've worked on. > > > https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/netdevice.h#L42 > > says that NET_NAME_UNKNOWN does not get passed to user space, but i > > assume NET_NAME_ENUM does. So maybe changing it would be an ABI > > change? > > Well, the name_assign_type ABI is kind of silly. I mean, userspace knows > that when one gets EINVAL trying to read the value, that really means > that the value is NET_NAME_UNKNOWN. But I won't propose changing that. > > However, what I do propose here is obviously already an ABI change; I > _want_ to expose more proper information in the case where the port has > a label, and just kept the NET_NAME_UNKNOWN for the eth%d case to make > the minimal change. But if people want to change that to NET_NAME_ENUM > while we're here, I can certainly do that. I can't think of any real > scenario where NET_NAME_ENUM would be treated differently than > NET_NAME_UNKNOWN - in both cases, userspace don't know that the name can > be trusted to be predictable. Apparently there may be a reason, see commit e9f656b7a214 ("net: ethernet: set default assignment identifier to NET_NAME_ENUM") so let's switch to ENUM while at it.
> Apparently there may be a reason, see commit e9f656b7a214 ("net: > ethernet: set default assignment identifier to NET_NAME_ENUM") > so let's switch to ENUM while at it. I would recommend two patches, making it easier to revert if we find something in userspace breaks. Andrew
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c index e504a18fc125..522fc1b6e8c6 100644 --- a/net/dsa/dsa2.c +++ b/net/dsa/dsa2.c @@ -1364,9 +1364,6 @@ static struct dsa_port *dsa_port_touch(struct dsa_switch *ds, int index) static int dsa_port_parse_user(struct dsa_port *dp, const char *name) { - if (!name) - name = "eth%d"; - dp->type = DSA_PORT_TYPE_USER; dp->name = name; diff --git a/net/dsa/slave.c b/net/dsa/slave.c index a9fde48cffd4..dfefcc4a9ccf 100644 --- a/net/dsa/slave.c +++ b/net/dsa/slave.c @@ -2374,16 +2374,25 @@ int dsa_slave_create(struct dsa_port *port) { struct net_device *master = dsa_port_to_master(port); struct dsa_switch *ds = port->ds; - const char *name = port->name; struct net_device *slave_dev; struct dsa_slave_priv *p; + const char *name; + int assign_type; int ret; if (!ds->num_tx_queues) ds->num_tx_queues = 1; + if (port->name) { + name = port->name; + assign_type = NET_NAME_PREDICTABLE; + } else { + name = "eth%d"; + assign_type = NET_NAME_UNKNOWN; + } + slave_dev = alloc_netdev_mqs(sizeof(struct dsa_slave_priv), name, - NET_NAME_UNKNOWN, ether_setup, + assign_type, ether_setup, ds->num_tx_queues, 1); if (slave_dev == NULL) return -ENOMEM;
When a user port has a label in device tree, the corresponding netdevice is "predictably named by the kernel". Expose that information properly for the benefit of userspace tools that make decisions based on the name_assign_type attribute, e.g. a systemd-udev rule with "kernel" in NamePolicy. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- net/dsa/dsa2.c | 3 --- net/dsa/slave.c | 13 +++++++++++-- 2 files changed, 11 insertions(+), 5 deletions(-)