Re: [PATCH v3] net: neighbour: introduce EVICT_NOCARRIER table option

Signed-off-by: James Prestwood <redacted>
---
 Documentation/networking/ip-sysctl.rst |  9 +++++++++
 include/net/neighbour.h                |  3 ++-
 include/uapi/linux/neighbour.h         |  1 +
 net/core/neighbour.c                   | 18 +++++++++++++-----
 net/ipv4/arp.c                         |  1 +
 net/ipv6/ndisc.c                       |  1 +
 6 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 16b8bf72feaf..e2aced01905a 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst

@@ -200,6 +200,15 @@ neigh/default/unres_qlen - INTEGER
 
 	Default: 101
 
+neigh/default/evict_nocarrier - BOOLEAN
+	Clears the neighbor cache on NOCARRIER events. This option is important
+	for wireless devices where the cache should not be cleared when roaming
+	between access points on the same network. In most cases this should
+	remain as the default (1).
+
+	- 1 - (default): Clear the neighbor cache on NOCARRIER events
+	- 0 - Do not clear neighbor cache on NOCARRIER events
+
 mtu_expires - INTEGER
 	Time, in seconds, that cached PMTU information is kept.
 

diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index e8e48be66755..71b28f83c3d3 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h

@@ -54,7 +54,8 @@ enum {
 	NEIGH_VAR_ANYCAST_DELAY,
 	NEIGH_VAR_PROXY_DELAY,
 	NEIGH_VAR_LOCKTIME,
-#define NEIGH_VAR_DATA_MAX (NEIGH_VAR_LOCKTIME + 1)
+	NEIGH_VAR_EVICT_NOCARRIER,
+#define NEIGH_VAR_DATA_MAX (NEIGH_VAR_EVICT_NOCARRIER + 1)
 	/* Following are used as a second way to access one of the above */
 	NEIGH_VAR_QUEUE_LEN, /* same data as NEIGH_VAR_QUEUE_LEN_BYTES */
 	NEIGH_VAR_RETRANS_TIME_MS, /* same data as NEIGH_VAR_RETRANS_TIME */

diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
index db05fb55055e..4322e5f42646 100644
--- a/include/uapi/linux/neighbour.h
+++ b/include/uapi/linux/neighbour.h

@@ -151,6 +151,7 @@ enum {
 	NDTPA_LOCKTIME,			/* u64, msecs */
 	NDTPA_QUEUE_LENBYTES,		/* u32 */
 	NDTPA_MCAST_REPROBES,		/* u32 */
+	NDTPA_EVICT_NOCARRIER,		/* u8 */
 	NDTPA_PAD,
 	__NDTPA_MAX
 };