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

Stanislav Fomichev
2026-03-20T15:41:17Z

On 03/20, Loktionov, Aleksandr wrote:
>
>
> > -----Original Message-----
> > From: Stanislav Fomichev <sdf@fomichev.me>
> > Sent: Friday, March 20, 2026 2:25 AM
> > To: netdev@vger.kernel.org
> > Cc: davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
> > pabeni@redhat.com; horms@kernel.org; corbet@lwn.net;
> > skhan@linuxfoundation.org; andrew+netdev@lunn.ch;
> > michael.chan@broadcom.com; pavan.chebbi@broadcom.com; Nguyen, Anthony
> > L <anthony.l.nguyen@intel.com>; Kitszel, Przemyslaw
> > <przemyslaw.kitszel@intel.com>; saeedm@nvidia.com; tariqt@nvidia.com;
> > mbloch@nvidia.com; alexanderduyck@fb.com; kernel-team@meta.com;
> > johannes@sipsolutions.net; sd@queasysnail.net; jianbol@nvidia.com;
> > dtatulea@nvidia.com; sdf@fomichev.me; mohsin.bashr@gmail.com; Keller,
> > Jacob E <jacob.e.keller@intel.com>; willemb@google.com;
> > skhawaja@google.com; bestswngs@gmail.com; Loktionov, Aleksandr
> > <aleksandr.loktionov@intel.com>; kees@kernel.org; linux-
> > doc@vger.kernel.org; linux-kernel@vger.kernel.org; intel-wired-
> > lan@lists.osuosl.org; linux-rdma@vger.kernel.org; linux-
> > wireless@vger.kernel.org; linux-kselftest@vger.kernel.org;
> > leon@kernel.org
> > Subject: [PATCH net-next v3 04/13] net: move promiscuity handling into
> > dev_rx_mode_work
> >
> > 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);
> Can you explain why do you add new hard precondition of ops lock must be held?

The context is that in f792709e0baa ("selftests: net: validate team flags
propagation") I had to add locking around NETDEV_CHANGE notifiers and
add that ugly `if (notify) netdev_ops_assert_locked` check. After this
patch I believe we are consistently calling __dev_set_promiscuity
with the ops lock (for ops locked netdev), so we can cleanup this enforcement
part.

> > 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);
> > }
>
> ...
>
> > __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);
> But it's being called here without any netdev_lock_ops(dev) ?

We have the following at the start of dev_rx_mode_work:
rtnl_lock();
netdev_lock_ops(dev);

Or am I looking at something else?