[PATCH net] neighbour: remove neigh_cleanup() method

[PATCH net] neighbour: remove neigh_cleanup() method

[Eric Dumazet]

neigh_cleanup() has not been used for seven years, and was a wrong design.

Messing with shared pointer in bond_neigh_init() without proper
memory barriers would at least trigger syzbot complains eventually.

It is time to remove this stuff.

Fixes: b63b70d87741 ("IPoIB: Use a private hash table for path lookup in xmit path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 drivers/net/bonding/bond_main.c | 8 --------
 include/net/neighbour.h         | 1 -
 net/core/neighbour.c            | 3 ---
 3 files changed, 12 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index fcb7c2f7f001b310075a8774ae67d8ea9e879575..6c72623e48e54d1d099a216c1181738667d32aec 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3712,18 +3712,10 @@ static int bond_neigh_init(struct neighbour *n)
 		return 0;
 
 	parms.neigh_setup = NULL;
-	parms.neigh_cleanup = NULL;
 	ret = slave_ops->ndo_neigh_setup(slave->dev, &parms);
 	if (ret)
 		return ret;
 
-	/* Assign slave's neigh_cleanup to neighbour in case cleanup is called
-	 * after the last slave has been detached.  Assumes that all slaves
-	 * utilize the same neigh_cleanup (true at this writing as only user
-	 * is ipoib).
-	 */
-	n->parms->neigh_cleanup = parms.neigh_cleanup;
-
 	if (!parms.neigh_setup)
 		return 0;
 
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index 6ad9ad47a9c54bfbd1772f404f4ae81bf9cc6dd3..8ec77bfdc1a413d0a45edc978075aedab817e62e 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -72,7 +72,6 @@ struct neigh_parms {
 	struct net_device *dev;
 	struct list_head list;
 	int	(*neigh_setup)(struct neighbour *);
-	void	(*neigh_cleanup)(struct neighbour *);
 	struct neigh_table *tbl;
 
 	void	*sysctl_table;
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 652da63690376b52d084a901310db39f4258aca3..920784a9b7ffaf0140c8e4427e327ec8867c2a2a 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -98,9 +98,6 @@ static int neigh_blackhole(struct neighbour *neigh, struct sk_buff *skb)
 
 static void neigh_cleanup_and_release(struct neighbour *neigh)
 {
-	if (neigh->parms->neigh_cleanup)
-		neigh->parms->neigh_cleanup(neigh);
-
 	trace_neigh_cleanup_and_release(neigh, 0);
 	__neigh_notify(neigh, RTM_DELNEIGH, 0, 0);
 	call_netevent_notifiers(NETEVENT_NEIGH_UPDATE, neigh);
-- 
2.24.0.393.g34dc348eaf-goog

Re: [PATCH net] neighbour: remove neigh_cleanup() method

[David Miller]

From: Eric Dumazet <edumazet@google.com>
Date: Sat,  7 Dec 2019 12:23:21 -0800

> neigh_cleanup() has not been used for seven years, and was a wrong design.
> 
> Messing with shared pointer in bond_neigh_init() without proper
> memory barriers would at least trigger syzbot complains eventually.
> 
> It is time to remove this stuff.
> 
> Fixes: b63b70d87741 ("IPoIB: Use a private hash table for path lookup in xmit path")
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied to net-next.