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neighbour: Annotate access to neigh_parms fields.

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NEIGH_VAR() is read locklessly in the fast path, and IPv6 ndisc uses
NEIGH_VAR_SET() locklessly.

The next patch will convert neightbl_dump_info() to RCU.

Let's annotate accesses to neigh_param with READ_ONCE() and WRITE_ONCE().

Note that ndisc_ifinfo_sysctl_change() uses &NEIGH_VAR() and we cannot
use '&' with READ_ONCE(), so NEIGH_VAR_PTR() is introduced.

Note also that NEIGH_VAR_INIT() does not need WRITE_ONCE() as it is before
parms is published.  Also, the only user hippi_neigh_setup_dev() is no
longer called since commit e3804cbebb ("net: remove COMPAT_NET_DEV_OPS"),
which looks wrong, but probably no one uses HIPPI and RoadRunner.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251022054004.2514876-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima
2025-10-22 05:39:46 +00:00
committed by Jakub Kicinski
parent 06d6322280
commit 35d7c70870
3 changed files with 22 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
include/net/neighbour.h
View File

@@ -92,15 +92,17 @@ struct neigh_parms {
static inline void neigh_var_set(struct neigh_parms *p, int index, int val)
{
set_bit(index, p->data_state);
p->data[index] = val;
WRITE_ONCE(p->data[index], val);
}
#define NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr])
#define __NEIGH_VAR(p, attr) ((p)->data[NEIGH_VAR_ ## attr])
#define NEIGH_VAR(p, attr) READ_ONCE(__NEIGH_VAR(p, attr))
#define NEIGH_VAR_PTR(p, attr) (&(__NEIGH_VAR(p, attr)))
/* In ndo_neigh_setup, NEIGH_VAR_INIT should be used.
* In other cases, NEIGH_VAR_SET should be used.
*/
#define NEIGH_VAR_INIT(p, attr, val) (NEIGH_VAR(p, attr) = val)
#define NEIGH_VAR_INIT(p, attr, val) (__NEIGH_VAR(p, attr) = val)
#define NEIGH_VAR_SET(p, attr, val) neigh_var_set(p, NEIGH_VAR_ ## attr, val)
static inline void neigh_parms_data_state_setall(struct neigh_parms *p)
@@ -378,6 +380,13 @@ struct net *neigh_parms_net(const struct neigh_parms *parms)
unsigned long neigh_rand_reach_time(unsigned long base);
static inline void neigh_set_reach_time(struct neigh_parms *p)
{
unsigned long base = NEIGH_VAR(p, BASE_REACHABLE_TIME);
WRITE_ONCE(p->reachable_time, neigh_rand_reach_time(base));
}
void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
struct sk_buff *skb);
struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net,

17
net/core/neighbour.c
View File

@@ -995,8 +995,7 @@ static void neigh_periodic_work(struct work_struct *work)
WRITE_ONCE(tbl->last_rand, jiffies);
list_for_each_entry(p, &tbl->parms_list, list)
p->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));
neigh_set_reach_time(p);
}
if (atomic_read(&tbl->entries) < READ_ONCE(tbl->gc_thresh1))
@@ -1749,8 +1748,7 @@ struct neigh_parms *neigh_parms_alloc(struct net_device *dev,
if (p) {
p->tbl = tbl;
refcount_set(&p->refcnt, 1);
p->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));
neigh_set_reach_time(p);
p->qlen = 0;
netdev_hold(dev, &p->dev_tracker, GFP_KERNEL);
p->dev = dev;
@@ -1810,8 +1808,7 @@ void neigh_table_init(int index, struct neigh_table *tbl)
list_add(&tbl->parms.list, &tbl->parms_list);
write_pnet(&tbl->parms.net, &init_net);
refcount_set(&tbl->parms.refcnt, 1);
tbl->parms.reachable_time =
neigh_rand_reach_time(NEIGH_VAR(&tbl->parms, BASE_REACHABLE_TIME));
neigh_set_reach_time(&tbl->parms);
tbl->parms.qlen = 0;
tbl->stats = alloc_percpu(struct neigh_statistics);
@@ -2194,7 +2191,7 @@ static int neightbl_fill_parms(struct sk_buff *skb, struct neigh_parms *parms)
NEIGH_VAR(parms, MCAST_PROBES)) ||
nla_put_u32(skb, NDTPA_MCAST_REPROBES,
NEIGH_VAR(parms, MCAST_REPROBES)) ||
nla_put_msecs(skb, NDTPA_REACHABLE_TIME, parms->reachable_time,
nla_put_msecs(skb, NDTPA_REACHABLE_TIME, READ_ONCE(parms->reachable_time),
NDTPA_PAD) ||
nla_put_msecs(skb, NDTPA_BASE_REACHABLE_TIME,
NEIGH_VAR(parms, BASE_REACHABLE_TIME), NDTPA_PAD) ||
@@ -2475,8 +2472,7 @@ static int neightbl_set(struct sk_buff *skb, struct nlmsghdr *nlh,
* only be effective after the next time neigh_periodic_work
* decides to recompute it (can be multiple minutes)
*/
p->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));
neigh_set_reach_time(p);
break;
case NDTPA_GC_STALETIME:
NEIGH_VAR_SET(p, GC_STALETIME,
@@ -3721,8 +3717,7 @@ static int neigh_proc_base_reachable_time(const struct ctl_table *ctl, int write
* only be effective after the next time neigh_periodic_work
* decides to recompute it
*/
p->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));
neigh_set_reach_time(p);
}
return ret;
}

8
net/ipv6/ndisc.c
View File

@@ -1449,7 +1449,7 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
BASE_REACHABLE_TIME, rtime);
NEIGH_VAR_SET(in6_dev->nd_parms,
GC_STALETIME, 3 * rtime);
in6_dev->nd_parms->reachable_time = neigh_rand_reach_time(rtime);
neigh_set_reach_time(in6_dev->nd_parms);
in6_dev->tstamp = jiffies;
send_ifinfo_notify = true;
}
@@ -1948,9 +1948,9 @@ int ndisc_ifinfo_sysctl_change(const struct ctl_table *ctl, int write, void *buf
ret = -1;
if (write && ret == 0 && dev && (idev = in6_dev_get(dev)) != NULL) {
if (ctl->data == &NEIGH_VAR(idev->nd_parms, BASE_REACHABLE_TIME))
idev->nd_parms->reachable_time =
neigh_rand_reach_time(NEIGH_VAR(idev->nd_parms, BASE_REACHABLE_TIME));
if (ctl->data == NEIGH_VAR_PTR(idev->nd_parms, BASE_REACHABLE_TIME))
neigh_set_reach_time(idev->nd_parms);
WRITE_ONCE(idev->tstamp, jiffies);
inet6_ifinfo_notify(RTM_NEWLINK, idev);
in6_dev_put(idev);