[PATCH v1 net-next 4/4] neighbour: Floor INTERVAL_PROBE_TIME_MS at 1000.

[Kuniyuki Iwashima <kuniyu@google.com>]

Previously, the lower bound of INTERVAL_PROBE_TIME_MS was capped
at 1s by commit ed6cd6a17896 ("net, neigh: Set lower cap for
neigh_managed_work rearming").

Later, commit 211da42eaa45 ("net, neigh: introduce
interval_probe_time_ms for periodic probe") changed the limit
to 1ms.

The limit actually did not work but was fixed with
netlink_range_validation by commit 6d79b223ec44 ("neighbour:
Enforce min/max to NDTPA_INTERVAL_PROBE_TIME_MS.").

neigh_table is now per-netns, and a user could hog CPU by setting
INTERVAL_PROBE_TIME_MS to a small value.

Let's floor the value at 1 second.

Suggested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/netdev/20260902143023.GA3966681@shredder/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
 Documentation/netlink/specs/rt-neigh.yaml | 2 +-
 Documentation/networking/ip-sysctl.rst    | 2 +-
 net/core/neighbour.c                      | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Documentation/netlink/specs/rt-neigh.yaml b/Documentation/netlink/specs/rt-neigh.yaml
index c8e55c98d564..7929e667cc7a 100644
--- a/Documentation/netlink/specs/rt-neigh.yaml
+++ b/Documentation/netlink/specs/rt-neigh.yaml
@@ -342,7 +342,7 @@ attribute-sets:
         name: interval-probe-time-ms
         type: u64
         checks:
-          min: 1
+          min: 1000
           max: 86400000
 
 operations:
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 685c84cf543d..b00bd77363d7 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -248,7 +248,7 @@ neigh/default/unres_qlen - INTEGER
 
 neigh/default/interval_probe_time_ms - INTEGER
 	The probe interval for neighbor entries with NTF_MANAGED flag,
-	the min value is 1, and the max value is 86400000 (1 day).
+	the min value is 1000 (1s), and the max value is 86400000 (1 day).
 
 	Default: 5000
 
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 6b0569aa5d64..92e3c83c0fe5 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2438,7 +2438,7 @@ static const struct nla_policy nl_neightbl_policy[NDTA_MAX+1] = {
 #define NTBL_PARM_MS_MAX	(24 * 60 * 60 * MSEC_PER_SEC)
 
 static const struct netlink_range_validation nl_ntbl_parm_ms_range = {
-	.min = 1,
+	.min = 1000,
 	.max = NTBL_PARM_MS_MAX,
 };
 
@@ -3701,7 +3701,7 @@ static int neigh_proc_dointvec_ms_jiffies_positive(const struct ctl_table *ctl,
 	struct ctl_table tmp = *ctl;
 	int ret, min, max;
 
-	min = msecs_to_jiffies(1);
+	min = HZ;
 	max = msecs_to_jiffies(NTBL_PARM_MS_MAX);
 
 	tmp.extra1 = &min;
-- 
2.56.0.385.gd3acb90ef8-goog