[PATCH 6.18 030/175] net: cpsw_new: Execute ndo_set_rx_mode callback in a work queue

Greg Kroah-Hartman
2026-02-09T14:26:41Z

From: Kevin Hao <haokexin@gmail.com>

commit c0b5dc73a38f954e780f93a549b8fe225235c07a upstream.

Commit 1767bb2d47b7 ("ipv6: mcast: Don't hold RTNL for
IPV6_ADD_MEMBERSHIP and MCAST_JOIN_GROUP.") removed the RTNL lock for
IPV6_ADD_MEMBERSHIP and MCAST_JOIN_GROUP operations. However, this
change triggered the following call trace on my BeagleBone Black board:
WARNING: net/8021q/vlan_core.c:236 at vlan_for_each+0x120/0x124, CPU#0: rpcbind/496
RTNL: assertion failed at net/8021q/vlan_core.c (236)
Modules linked in:
CPU: 0 UID: 997 PID: 496 Comm: rpcbind Not tainted 6.19.0-rc6-next-20260122-yocto-standard+ #8 PREEMPT
Hardware name: Generic AM33XX (Flattened Device Tree)
Call trace:
unwind_backtrace from show_stack+0x28/0x2c
show_stack from dump_stack_lvl+0x30/0x38
dump_stack_lvl from __warn+0xb8/0x11c
__warn from warn_slowpath_fmt+0x130/0x194
warn_slowpath_fmt from vlan_for_each+0x120/0x124
vlan_for_each from cpsw_add_mc_addr+0x54/0xd8
cpsw_add_mc_addr from __hw_addr_ref_sync_dev+0xc4/0xec
__hw_addr_ref_sync_dev from __dev_mc_add+0x78/0x88
__dev_mc_add from igmp6_group_added+0x84/0xec
igmp6_group_added from __ipv6_dev_mc_inc+0x1fc/0x2f0
__ipv6_dev_mc_inc from __ipv6_sock_mc_join+0x124/0x1b4
__ipv6_sock_mc_join from do_ipv6_setsockopt+0x84c/0x1168
do_ipv6_setsockopt from ipv6_setsockopt+0x88/0xc8
ipv6_setsockopt from do_sock_setsockopt+0xe8/0x19c
do_sock_setsockopt from __sys_setsockopt+0x84/0xac
__sys_setsockopt from ret_fast_syscall+0x0/0x5

This trace occurs because vlan_for_each() is called within
cpsw_ndo_set_rx_mode(), which expects the RTNL lock to be held.
Since modifying vlan_for_each() to operate without the RTNL lock is not
straightforward, and because ndo_set_rx_mode() is invoked both with and
without the RTNL lock across different code paths, simply adding
rtnl_lock() in cpsw_ndo_set_rx_mode() is not a viable solution.

To resolve this issue, we opt to execute the actual processing within
a work queue, following the approach used by the icssg-prueth driver.

Fixes: 1767bb2d47b7 ("ipv6: mcast: Don't hold RTNL for IPV6_ADD_MEMBERSHIP and MCAST_JOIN_GROUP.")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260203-bbb-v5-1-ea0ea217a85c@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/ti/cpsw_new.c | 34 ++++++++++++++++++++++++-----
drivers/net/ethernet/ti/cpsw_priv.h | 1 +
2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
index ab88d4c02cbd..21af0a10626a 100644
--- a/drivers/net/ethernet/ti/cpsw_new.c
+++ b/drivers/net/ethernet/ti/cpsw_new.c
@@ -248,16 +248,22 @@ static int cpsw_purge_all_mc(struct net_device *ndev, const u8 *addr, int num)
return 0;
}

-static void cpsw_ndo_set_rx_mode(struct net_device *ndev)
+static void cpsw_ndo_set_rx_mode_work(struct work_struct *work)
{
- struct cpsw_priv *priv = netdev_priv(ndev);
+ struct cpsw_priv *priv = container_of(work, struct cpsw_priv, rx_mode_work);
struct cpsw_common *cpsw = priv->cpsw;
+ struct net_device *ndev = priv->ndev;

+ rtnl_lock();
+ if (!netif_running(ndev))
+ goto unlock_rtnl;
+
+ netif_addr_lock_bh(ndev);
if (ndev->flags & IFF_PROMISC) {
/* Enable promiscuous mode */
cpsw_set_promiscious(ndev, true);
cpsw_ale_set_allmulti(cpsw->ale, IFF_ALLMULTI, priv->emac_port);
- return;
+ goto unlock_addr;
}

/* Disable promiscuous mode */
@@ -270,6 +276,18 @@ static void cpsw_ndo_set_rx_mode(struct net_device *ndev)
/* add/remove mcast address either for real netdev or for vlan */
__hw_addr_ref_sync_dev(&ndev->mc, ndev, cpsw_add_mc_addr,
cpsw_del_mc_addr);
+
+unlock_addr:
+ netif_addr_unlock_bh(ndev);
+unlock_rtnl:
+ rtnl_unlock();
+}
+
+static void cpsw_ndo_set_rx_mode(struct net_device *ndev)
+{
+ struct cpsw_priv *priv = netdev_priv(ndev);
+
+ schedule_work(&priv->rx_mode_work);
}

static unsigned int cpsw_rxbuf_total_len(unsigned int len)
@@ -1398,6 +1416,7 @@ static int cpsw_create_ports(struct cpsw_common *cpsw)
priv->msg_enable = netif_msg_init(debug_level, CPSW_DEBUG);
priv->emac_port = i + 1;
priv->tx_packet_min = CPSW_MIN_PACKET_SIZE;
+ INIT_WORK(&priv->rx_mode_work, cpsw_ndo_set_rx_mode_work);

if (is_valid_ether_addr(slave_data->mac_addr)) {
ether_addr_copy(priv->mac_addr, slave_data->mac_addr);
@@ -1447,13 +1466,18 @@ static int cpsw_create_ports(struct cpsw_common *cpsw)

static void cpsw_unregister_ports(struct cpsw_common *cpsw)
{
+ struct net_device *ndev;
+ struct cpsw_priv *priv;
int i = 0;

for (i = 0; i < cpsw->data.slaves; i++) {
- if (!cpsw->slaves[i].ndev)
+ ndev = cpsw->slaves[i].ndev;
+ if (!ndev)
continue;

- unregister_netdev(cpsw->slaves[i].ndev);
+ priv = netdev_priv(ndev);
+ unregister_netdev(ndev);
+ disable_work_sync(&priv->rx_mode_work);
}
}

diff --git a/drivers/net/ethernet/ti/cpsw_priv.h b/drivers/net/ethernet/ti/cpsw_priv.h
index 91add8925e23..acb6181c5c9e 100644
--- a/drivers/net/ethernet/ti/cpsw_priv.h
+++ b/drivers/net/ethernet/ti/cpsw_priv.h
@@ -391,6 +391,7 @@ struct cpsw_priv {
u32 tx_packet_min;
struct cpsw_ale_ratelimit ale_bc_ratelimit;
struct cpsw_ale_ratelimit ale_mc_ratelimit;
+ struct work_struct rx_mode_work;
};

#define ndev_to_cpsw(ndev) (((struct cpsw_priv *)netdev_priv(ndev))->cpsw)
--
2.53.0