[PATCH] net: neighbour: add neigh_parms_lookup_dev() helper

[PATCH] net: neighbour: add neigh_parms_lookup_dev() helper

[Paritosh Potukuchi]

Provide a helper to lookup neigh_parms associated
with a given (neigh_table, net_device) pair.

The existing lookup_neigh_parms() helper is internal to the
neighbour subsystem and cannot be used by other subsystems.
Some stacked/virtual devices like bond require access to the
underlying device's neigh_parms.

neigh_parms_lookup_dev() is designed to be a wrapper around
lookup_neigh_parms(). The function provides controlled access
to per device neigh_parms.

The caller is expected to hold rcu_read_lock().

This does not break any existing functionality.

Signed-off-by: Paritosh Potukuchi <paritosh.potukuchi@amd.com>
---
 include/net/neighbour.h | 2 ++
 net/core/neighbour.c    | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 8860cc2175fc..1b3b06eda886 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -438,6 +438,8 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 			  proc_handler *proc_handler);
 void neigh_sysctl_unregister(struct neigh_parms *p);
 
+struct neigh_parms *neigh_parms_lookup_dev(struct neigh_table *tbl, struct net_device *dev);
+
 static inline void __neigh_parms_put(struct neigh_parms *parms)
 {
 	refcount_dec(&parms->refcnt);
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 1349c0eedb64..6d32c2668af3 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1757,6 +1757,14 @@ static inline struct neigh_parms *lookup_neigh_parms(struct neigh_table *tbl,
 	return NULL;
 }
 
+/* Caller must hold rcu_read_lock()*/
+
+struct neigh_parms *neigh_parms_lookup_dev(struct neigh_table *tbl, struct net_device *dev)
+{
+	return lookup_neigh_parms(tbl, dev_net(dev), dev->ifindex);
+}
+EXPORT_SYMBOL(neigh_parms_lookup_dev);
+
 struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
 				      struct neigh_table *tbl)
 {
-- 
2.43.0

Re: [PATCH] net: neighbour: add neigh_parms_lookup_dev() helper

[Kuniyuki Iwashima]

On Mon, Jun 29, 2026 at 8:58 AM Paritosh Potukuchi
<paritoshpotukuchi@gmail.com> wrote:
>
> Provide a helper to lookup neigh_parms associated
> with a given (neigh_table, net_device) pair.
>
> The existing lookup_neigh_parms() helper is internal to the
> neighbour subsystem and cannot be used by other subsystems.
> Some stacked/virtual devices like bond require access to the
> underlying device's neigh_parms.
>
> neigh_parms_lookup_dev() is designed to be a wrapper around
> lookup_neigh_parms(). The function provides controlled access
> to per device neigh_parms.

Please post a series of patches with the neigh_parms_lookup_dev()
users.


>
> The caller is expected to hold rcu_read_lock().
>
> This does not break any existing functionality.
>
> Signed-off-by: Paritosh Potukuchi <paritosh.potukuchi@amd.com>
> ---
>  include/net/neighbour.h | 2 ++
>  net/core/neighbour.c    | 8 ++++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/include/net/neighbour.h b/include/net/neighbour.h
> index 8860cc2175fc..1b3b06eda886 100644
> --- a/include/net/neighbour.h
> +++ b/include/net/neighbour.h
> @@ -438,6 +438,8 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
>                           proc_handler *proc_handler);
>  void neigh_sysctl_unregister(struct neigh_parms *p);
>
> +struct neigh_parms *neigh_parms_lookup_dev(struct neigh_table *tbl, struct net_device *dev);
> +
>  static inline void __neigh_parms_put(struct neigh_parms *parms)
>  {
>         refcount_dec(&parms->refcnt);
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 1349c0eedb64..6d32c2668af3 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -1757,6 +1757,14 @@ static inline struct neigh_parms *lookup_neigh_parms(struct neigh_table *tbl,
>         return NULL;
>  }
>
> +/* Caller must hold rcu_read_lock()*/
> +
> +struct neigh_parms *neigh_parms_lookup_dev(struct neigh_table *tbl, struct net_device *dev)
> +{
> +       return lookup_neigh_parms(tbl, dev_net(dev), dev->ifindex);
> +}
> +EXPORT_SYMBOL(neigh_parms_lookup_dev);
> +
>  struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
>                                       struct neigh_table *tbl)
>  {
> --
> 2.43.0
>

Re: [PATCH] net: neighbour: add neigh_parms_lookup_dev() helper

[Kuniyuki Iwashima]

On Mon, Jun 29, 2026 at 11:35 AM Paritosh Potukuchi
<paritoshpotukuchi@gmail.com> wrote:
>
> >  Please post a series of patches with the neigh_parms_lookup_dev()
> users.
> Sure. I'll post a series of patches, with the neigh_parms_lookup_dev() users.

Please wait 24h before the next submission.
https://docs.kernel.org/7.1/process/maintainer-netdev.html#tl-dr


>
> On Mon, 29 Jun 2026 at 23:53, Kuniyuki Iwashima <kuniyu@google.com> wrote:
>>
>> On Mon, Jun 29, 2026 at 8:58 AM Paritosh Potukuchi
>> <paritoshpotukuchi@gmail.com> wrote:
>> >
>> > Provide a helper to lookup neigh_parms associated
>> > with a given (neigh_table, net_device) pair.
>> >
>> > The existing lookup_neigh_parms() helper is internal to the
>> > neighbour subsystem and cannot be used by other subsystems.
>> > Some stacked/virtual devices like bond require access to the
>> > underlying device's neigh_parms.
>> >
>> > neigh_parms_lookup_dev() is designed to be a wrapper around
>> > lookup_neigh_parms(). The function provides controlled access
>> > to per device neigh_parms.
>>
>> Please post a series of patches with the neigh_parms_lookup_dev()
>> users.
>>
>>
>> >
>> > The caller is expected to hold rcu_read_lock().
>> >
>> > This does not break any existing functionality.
>> >
>> > Signed-off-by: Paritosh Potukuchi <paritosh.potukuchi@amd.com>
>> > ---
>> >  include/net/neighbour.h | 2 ++
>> >  net/core/neighbour.c    | 8 ++++++++
>> >  2 files changed, 10 insertions(+)
>> >
>> > diff --git a/include/net/neighbour.h b/include/net/neighbour.h
>> > index 8860cc2175fc..1b3b06eda886 100644
>> > --- a/include/net/neighbour.h
>> > +++ b/include/net/neighbour.h
>> > @@ -438,6 +438,8 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
>> >                           proc_handler *proc_handler);
>> >  void neigh_sysctl_unregister(struct neigh_parms *p);
>> >
>> > +struct neigh_parms *neigh_parms_lookup_dev(struct neigh_table *tbl, struct net_device *dev);
>> > +
>> >  static inline void __neigh_parms_put(struct neigh_parms *parms)
>> >  {
>> >         refcount_dec(&parms->refcnt);
>> > diff --git a/net/core/neighbour.c b/net/core/neighbour.c
>> > index 1349c0eedb64..6d32c2668af3 100644
>> > --- a/net/core/neighbour.c
>> > +++ b/net/core/neighbour.c
>> > @@ -1757,6 +1757,14 @@ static inline struct neigh_parms *lookup_neigh_parms(struct neigh_table *tbl,
>> >         return NULL;
>> >  }
>> >
>> > +/* Caller must hold rcu_read_lock()*/
>> > +
>> > +struct neigh_parms *neigh_parms_lookup_dev(struct neigh_table *tbl, struct net_device *dev)
>> > +{
>> > +       return lookup_neigh_parms(tbl, dev_net(dev), dev->ifindex);
>> > +}
>> > +EXPORT_SYMBOL(neigh_parms_lookup_dev);
>> > +
>> >  struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
>> >                                       struct neigh_table *tbl)
>> >  {
>> > --
>> > 2.43.0
>> >