[Intel-wired-lan] [PATCH net-next v3 04/13] net: move promiscuity handling into dev_rx_mode_work

Stanislav Fomichev
2026-03-20T01:25:13Z

Move unicast promiscuity tracking into dev_rx_mode_work so it runs
under netdev_ops_lock instead of under the addr_lock spinlock. This
is required because __dev_set_promiscuity calls dev_change_rx_flags
and __dev_notify_flags, both of which may need to sleep.

Change ASSERT_RTNL() to netdev_ops_assert_locked() in
__dev_set_promiscuity, netif_set_allmulti and __dev_change_flags
since these are now called from the work queue under the ops lock.

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
Documentation/networking/netdevices.rst | 4 ++
net/core/dev.c | 79 +++++++++++++++++--------
2 files changed, 57 insertions(+), 26 deletions(-)

diff --git a/Documentation/networking/netdevices.rst b/Documentation/networking/netdevices.rst
index dc83d78d3b27..5cdaa1a3dcc8 100644
--- a/Documentation/networking/netdevices.rst
+++ b/Documentation/networking/netdevices.rst
@@ -298,6 +298,10 @@ struct net_device synchronization rules
Notes: Sleepable version of ndo_set_rx_mode. Receives snapshots
of the unicast and multicast address lists.

+ndo_change_rx_flags:
+ Synchronization: rtnl_lock() semaphore. In addition, netdev instance
+ lock if the driver implements queue management or shaper API.
+
ndo_setup_tc:
``TC_SETUP_BLOCK`` and ``TC_SETUP_FT`` are running under NFT locks
(i.e. no ``rtnl_lock`` and no device instance lock). The rest of
diff --git a/net/core/dev.c b/net/core/dev.c
index fedc423306fc..fc5c9b14faa0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9574,7 +9574,7 @@ static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
kuid_t uid;
kgid_t gid;

- ASSERT_RTNL();
+ netdev_ops_assert_locked(dev);

promiscuity = dev->promiscuity + inc;
if (promiscuity == 0) {
@@ -9610,16 +9610,8 @@ static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)

dev_change_rx_flags(dev, IFF_PROMISC);
}
- if (notify) {
- /* The ops lock is only required to ensure consistent locking
- * for `NETDEV_CHANGE` notifiers. This function is sometimes
- * called without the lock, even for devices that are ops
- * locked, such as in `dev_uc_sync_multiple` when using
- * bonding or teaming.
- */
- netdev_ops_assert_locked(dev);
+ if (notify)
__dev_notify_flags(dev, old_flags, IFF_PROMISC, 0, NULL);
- }
return 0;
}

@@ -9641,7 +9633,7 @@ int netif_set_allmulti(struct net_device *dev, int inc, bool notify)
unsigned int old_flags = dev->flags, old_gflags = dev->gflags;
unsigned int allmulti, flags;

- ASSERT_RTNL();
+ netdev_ops_assert_locked(dev);

allmulti = dev->allmulti + inc;
if (allmulti == 0) {
@@ -9671,12 +9663,36 @@ int netif_set_allmulti(struct net_device *dev, int inc, bool notify)
return 0;
}

+/**
+ * dev_uc_promisc_update() - evaluate whether uc_promisc should be toggled.
+ * @dev: device
+ *
+ * Must be called under netif_addr_lock_bh.
+ * Return: +1 to enter promisc, -1 to leave, 0 for no change.
+ */
+static int dev_uc_promisc_update(struct net_device *dev)
+{
+ if (dev->priv_flags & IFF_UNICAST_FLT)
+ return 0;
+
+ if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
+ dev->uc_promisc = true;
+ return 1;
+ }
+ if (netdev_uc_empty(dev) && dev->uc_promisc) {
+ dev->uc_promisc = false;
+ return -1;
+ }
+ return 0;
+}
+
static void dev_rx_mode_work(struct work_struct *work)
{
struct net_device *dev = container_of(work, struct net_device,
rx_mode_work);
struct netdev_hw_addr_list uc_snap, mc_snap, uc_ref, mc_ref;
const struct net_device_ops *ops = dev->netdev_ops;
+ int promisc_inc;
int err;

__hw_addr_init(&uc_snap);
@@ -9704,16 +9720,29 @@ static void dev_rx_mode_work(struct work_struct *work)
if (!err)
err = __hw_addr_list_snapshot(&mc_ref, &dev->mc,
dev->addr_len);
- netif_addr_unlock_bh(dev);

if (err) {
netdev_WARN(dev, "failed to sync uc/mc addresses\n");
__hw_addr_flush(&uc_snap);
__hw_addr_flush(&uc_ref);
__hw_addr_flush(&mc_snap);
+ netif_addr_unlock_bh(dev);
goto out;
}

+ promisc_inc = dev_uc_promisc_update(dev);
+
+ netif_addr_unlock_bh(dev);
+ } else {
+ netif_addr_lock_bh(dev);
+ promisc_inc = dev_uc_promisc_update(dev);
+ netif_addr_unlock_bh(dev);
+ }
+
+ if (promisc_inc)
+ __dev_set_promiscuity(dev, promisc_inc, false);
+
+ if (ops->ndo_set_rx_mode_async) {
ops->ndo_set_rx_mode_async(dev, &uc_snap, &mc_snap);

netif_addr_lock_bh(dev);
@@ -9722,6 +9751,10 @@ static void dev_rx_mode_work(struct work_struct *work)
__hw_addr_list_reconcile(&dev->mc, &mc_snap,
&mc_ref, dev->addr_len);
netif_addr_unlock_bh(dev);
+ } else if (ops->ndo_set_rx_mode) {
+ netif_addr_lock_bh(dev);
+ ops->ndo_set_rx_mode(dev);
+ netif_addr_unlock_bh(dev);
}

out:
@@ -9740,28 +9773,22 @@ static void dev_rx_mode_work(struct work_struct *work)
void __dev_set_rx_mode(struct net_device *dev)
{
const struct net_device_ops *ops = dev->netdev_ops;
+ int promisc_inc;

/* dev_open will call this function so the list will stay sane. */
if (!netif_up_and_present(dev))
return;

- if (ops->ndo_set_rx_mode_async) {
+ if (ops->ndo_set_rx_mode_async || ops->ndo_change_rx_flags) {
queue_work(rx_mode_wq, &dev->rx_mode_work);
return;
}

- if (!(dev->priv_flags & IFF_UNICAST_FLT)) {
- /* Unicast addresses changes may only happen under the rtnl,
- * therefore calling __dev_set_promiscuity here is safe.
- */
- if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
- __dev_set_promiscuity(dev, 1, false);
- dev->uc_promisc = true;
- } else if (netdev_uc_empty(dev) && dev->uc_promisc) {
- __dev_set_promiscuity(dev, -1, false);
- dev->uc_promisc = false;
- }
- }
+ /* Legacy path for non-ops locked HW devices. */
+
+ promisc_inc = dev_uc_promisc_update(dev);
+ if (promisc_inc)
+ __dev_set_promiscuity(dev, promisc_inc, false);

if (ops->ndo_set_rx_mode)
ops->ndo_set_rx_mode(dev);
@@ -9811,7 +9838,7 @@ int __dev_change_flags(struct net_device *dev, unsigned int flags,
unsigned int old_flags = dev->flags;
int ret;

- ASSERT_RTNL();
+ netdev_ops_assert_locked(dev);

/*
* Set the flags on our device.
--
2.53.0