Re: [PATCH net-next v11 6/9] net: dsa: lan9645x: add vlan support
From: Paolo Abeni
Date: Tue Aug 11 2026 - 06:36:54 EST
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---
--- Patch [6]: [PATCH net-next v11 6/9] net: dsa: lan9645x: add vlan support ---
commit 48ea20348797be1134c296e1f56d305fbc50bbe3
Author: Jens Emil Schulz Østergaard <jensemil.schulzostergaard@xxxxxxxxxxxxx>
net: dsa: lan9645x: add vlan support
This adds a new lan9645x_vlan.c implementing port_vlan_filtering,
port_vlan_add and port_vlan_del, backed by a software shadow of the
hardware VLAN table in lan9645x->vlans[]. VID 4095 is reserved as the
port VLAN of standalone ports and VID 0 is used for VLAN-unaware bridge
ports.
> diff --git a/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c b/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c
> index c145d28ffbb99..3281726284dc2 100644
> --- a/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c
> +++ b/drivers/net/dsa/microchip/lan9645x/lan9645x_main.c
[ ... ]
> @@ -521,6 +524,7 @@ static int lan9645x_port_bridge_join(struct dsa_switch *ds, int port,
>
> lan9645x->bridge_mask |= BIT(p->chip_port);
> __lan9645x_port_set_host_flood(lan9645x);
> + lan9645x_vlan_clear_hostmode(p);
>
> mutex_unlock(&lan9645x->fwd_domain_lock);
>
[ ... ]
> @@ -576,11 +580,52 @@ static void lan9645x_port_bridge_leave(struct dsa_switch *ds, int port,
> +static int lan9645x_port_vlan_add(struct dsa_switch *ds, int port,
> + const struct switchdev_obj_port_vlan *vlan,
> + struct netlink_ext_ack *extack)
> +{
> + struct lan9645x *lan9645x = ds->priv;
> + struct lan9645x_port *p;
> + bool pvid, untagged;
> +
> + p = lan9645x_to_port(lan9645x, port);
> + pvid = !!(vlan->flags & BRIDGE_VLAN_INFO_PVID);
> + untagged = !!(vlan->flags & BRIDGE_VLAN_INFO_UNTAGGED);
> +
> + return lan9645x_vlan_port_add_vlan(p, vlan->vid, pvid, untagged,
> + extack);
> +}
[ ... ]
> diff --git a/drivers/net/dsa/microchip/lan9645x/lan9645x_main.h b/drivers/net/dsa/microchip/lan9645x/lan9645x_main.h
> index a0cd1707e1149..248c4ab59f1a8 100644
> --- a/drivers/net/dsa/microchip/lan9645x/lan9645x_main.h
> +++ b/drivers/net/dsa/microchip/lan9645x/lan9645x_main.h
[ ... ]
> @@ -156,6 +157,17 @@ enum lan9645x_vlan_port_tag {
> LAN9645X_TAG_ALL = 3,
> };
>
> +struct lan9645x_vlan {
> + u32 portmask: 10, /* ports 0-8 + CPU port module */
> + untagged: 9, /* ports 0-8 */
> + src_chk: 1,
> + mir: 1,
> + lrn_dis: 1,
> + prv_vlan: 1,
> + fld_dis: 1,
> + s_fwd_ena: 1;
> +};
> +
[ ... ]
> @@ -180,6 +192,9 @@ struct lan9645x {
> u16 bridge_fwd_mask; /* Mask for forwarding bridged ports */
> struct mutex fwd_domain_lock; /* lock forwarding configuration */
>
> + /* VLAN entries */
> + struct lan9645x_vlan vlans[VLAN_N_VID];
> +
> int num_port_dis;
> };
[ ... ]
> diff --git a/drivers/net/dsa/microchip/lan9645x/lan9645x_port.c b/drivers/net/dsa/microchip/lan9645x/lan9645x_port.c
> index 0642b59419c25..0548904dc4bd2 100644
> --- a/drivers/net/dsa/microchip/lan9645x/lan9645x_port.c
> +++ b/drivers/net/dsa/microchip/lan9645x/lan9645x_port.c
> @@ -210,5 +210,8 @@ int lan9645x_port_setup(struct dsa_switch *ds, int port)
> ANA_PORT_CFG_PORTID_VAL,
> lan9645x, ANA_PORT_CFG(p->chip_port));
>
> + if (p->chip_port != lan9645x->npi)
> + lan9645x_vlan_set_hostmode(p);
> +
> return 0;
> }
> diff --git a/drivers/net/dsa/microchip/lan9645x/lan9645x_vlan.c b/drivers/net/dsa/microchip/lan9645x/lan9645x_vlan.c
> new file mode 100644
> index 0000000000000..e2116132b4d48
> --- /dev/null
> +++ b/drivers/net/dsa/microchip/lan9645x/lan9645x_vlan.c
[ ... ]
> +static int lan9645x_vlan_hw_wr(struct lan9645x *lan9645x, u16 vid)
> +{
> + struct lan9645x_vlan *v = &lan9645x->vlans[vid];
> + bool cpu_dis = !(v->portmask & BIT(lan9645x->num_phys_ports));
> + u32 val;
> + int err;
> +
> + val = ANA_VLANTIDX_VLAN_PGID_CPU_DIS_SET(cpu_dis) |
> + ANA_VLANTIDX_V_INDEX_SET(vid) |
> + ANA_VLANTIDX_VLAN_SEC_FWD_ENA_SET(v->s_fwd_ena) |
> + ANA_VLANTIDX_VLAN_FLOOD_DIS_SET(v->fld_dis) |
> + ANA_VLANTIDX_VLAN_PRIV_VLAN_SET(v->prv_vlan) |
> + ANA_VLANTIDX_VLAN_LEARN_DISABLED_SET(v->lrn_dis) |
> + ANA_VLANTIDX_VLAN_MIRROR_SET(v->mir) |
> + ANA_VLANTIDX_VLAN_SRC_CHK_SET(v->src_chk);
> +
> + lan_wr(val, lan9645x, ANA_VLANTIDX);
> + lan_wr(ANA_VLAN_PORT_MASK_VLAN_PORT_MASK_SET(v->portmask),
> + lan9645x, ANA_VLAN_PORT_MASK);
> + lan_wr(ANA_VLANACCESS_VLAN_TBL_CMD_SET(VLANACCESS_CMD_WRITE),
> + lan9645x, ANA_VLANACCESS);
[Severity: High]
[Finding: main-5-5]
[Sources: opus-5]
Should this three-register indirect transaction be serialized by a lock?
The MAC table engine in this driver is protected by mact_lock:
struct mutex mact_lock; /* serialize mac table register access */
but the VLAN table access engine has no equivalent, and there is no
lockdep_assert_held() here.
lan9645x_vlan_set_hostmode() is now called from .port_setup:
lan9645x_port_setup()
if (p->chip_port != lan9645x->npi)
lan9645x_vlan_set_hostmode(p)
lan9645x_vlan_hw_wr(p->lan9645x, HOST_PVID)
and .port_setup runs from the DSA probe path without rtnl_lock and
without fwd_domain_lock:
net/dsa/devlink.c:dsa_port_devlink_setup() {
if (ds->ops->port_setup) {
err = ds->ops->port_setup(ds, dp->index);
...
}
dsa_port_devlink_setup() runs at the start of dsa_port_setup(), before
dsa_user_create() registers this port's netdev, while the netdevs of the
ports already processed are live. So while swp1..swpN are still going
through lan9645x_port_setup(), userspace can enslave swp0:
CPU0 (probe, no locks held) CPU1 (rtnl, bridge join / vlan add)
lan9645x_vlan_set_hostmode() lan9645x_port_vlan_add()
lan9645x_vlan_hw_wr(.., 4095) lan9645x_vlan_port_add_vlan()
lan9645x_vlan_hw_wr(.., 100)
Can the two transactions interleave like this?
CPU1: lan_wr(V_INDEX=100, ANA_VLANTIDX)
CPU0: lan_wr(V_INDEX=4095, ANA_VLANTIDX)
CPU0: lan_wr(mask(4095), ANA_VLAN_PORT_MASK)
CPU0: lan_wr(CMD_WRITE, ANA_VLANACCESS)
CPU1: lan_wr(mask(100), ANA_VLAN_PORT_MASK)
CPU1: lan_wr(CMD_WRITE, ANA_VLANACCESS)
That would commit mask(100) into the HOST_PVID (4095) entry and leave
vid 100 without a member mask, i.e. either standalone ports lose their
isolation domain or the new VLAN blackholes traffic.
There is also the shadow update itself. lan9645x_vlan_set_hostmode() and
lan9645x_vlan_clear_hostmode() both do a non-atomic read-modify-write of
the same u32 bitfield word:
p->lan9645x->vlans[HOST_PVID].portmask |= BIT(p->chip_port);
...
p->lan9645x->vlans[HOST_PVID].portmask &= ~BIT(p->chip_port);
portmask:10 shares the word with untagged:9 and the flag bits, and
lan9645x_port_bridge_join() calls lan9645x_vlan_clear_hostmode() under
fwd_domain_lock while lan9645x_port_setup() calls
lan9645x_vlan_set_hostmode() with no lock at all, so the lock sets do not
intersect. Can one of these updates be lost?
> +
> + /* The VLAN access engine completes in a fixed ~1us vs the polling
> + * timeout of 100_000 us. A timeout here therefore likely means the
> + * register bus itself is dead, not that the VLAN op failed. There is no
> + * meaningful recovery at runtime, so this function logs via dev_err()
> + * and runtime callers discard the return value. Only
> + * lan9645x_vlan_init() treats this as fatal so that probe fails early
> + * on a broken bus.
> + */
> + err = lan9645x_vlan_wait_for_completion(lan9645x);
> + if (err)
> + dev_err(lan9645x->dev, "Vlan set mask failed\n");
> +
> + return err;
> +}
[ ... ]
> +int lan9645x_vlan_port_add_vlan(struct lan9645x_port *p, u16 vid, bool pvid,
> + bool untagged, struct netlink_ext_ack *extack)
> +{
[ ... ]
> + lan9645x_vlan_port_get_info(lan9645x, p->chip_port, &info);
> +
> + if (info.untagged > 1 && info.tagged) {
> + *v = old_vlan;
> + p->pvid = old_pvid;
> + NL_SET_ERR_MSG_MOD(extack, "Only support 1 untagged port VLAN");
> + return -EBUSY;
> + }
[Severity: Low]
[Finding: main-1-1]
[Sources: opus-5]
This isn't a bug, but could the commit message mention this restriction?
The commit message says only "Add VLAN support for VLAN-aware and
VLAN-unaware bridges", while this rejects an otherwise legal bridge
configuration: a second
bridge vlan add dev swpN vid B untagged
fails with -EBUSY once the port already has one untagged VLAN plus at
least one tagged VLAN.
The changelog also notes an expected selftest failure with respect to
ctag/stag conformance, but that text is below the --- line and is dropped
when the patch is applied, so nothing about either limitation survives in
the tree.
> +
> + lan9645x_vlan_hw_wr(lan9645x, vid);
> + lan9645x_vlan_port_apply_ingress(p);
> + lan9645x_vlan_port_apply_egress(p, &info);
> +
> + return 0;
> +}
[ ... ]
> +void lan9645x_vlan_set_hostmode(struct lan9645x_port *p)
> +{
> + p->vlan_aware = false;
> + p->lan9645x->vlans[HOST_PVID].portmask |= BIT(p->chip_port);
> + lan9645x_vlan_hw_wr(p->lan9645x, HOST_PVID);
> + lan9645x_vlan_port_apply(p);
> +}
> +
> +void lan9645x_vlan_clear_hostmode(struct lan9645x_port *p)
> +{
> + p->lan9645x->vlans[HOST_PVID].portmask &= ~BIT(p->chip_port);
> + lan9645x_vlan_hw_wr(p->lan9645x, HOST_PVID);
> + lan9645x_vlan_port_apply(p);
> +}
[ ... ]
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