From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E90A54D0A14; Fri, 9 Oct 2026 14:15:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791555337; cv=none; b=fgda5ky8RAJjiUfzueUeCKg+jPTyOvwES99rVQ5u7Z6yFZrFK7h31WTDohthnhX/xIofTlCXwCKBdLSV0t8OXBT4n5/+o2F8TMpbZa0SDk0BLj2+CawHoy1tSxToe3OM9IxpZc33xpNcYhuPszLT4dHrjMEp+4pCOlamUc5mh64= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791555337; c=relaxed/simple; bh=TMwSAAQb29JelGeE4TSjv9sR8IO5hsBIVnNJdTyk2is=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qTPKxT7BxQQS9g1/rdYgmZuDslkK6AmsEPLAmwLul5pBqt7b8ETnVm/WYEsC6nNYXtGL8k8oJQTmbpUTiK1jkYqrljhd1njGwQsWazf0Z2YJ7Kul7tmem1RWXBUcDh08lRwvfhbVjnjS9FJdlJz5oxAP6N4Ej7qkJhRPkHotWls= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kxXTrAQJ; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kxXTrAQJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB2151F00893; Fri, 9 Oct 2026 14:15:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791555330; bh=YPrDF2meLbiw6q4SmDpyhQe4AYbp+bQn9+q7Z5ABJ90=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kxXTrAQJ9OsiXzjk47QLYgQmAsebCfb/tE5Fc8BBbjm/1/QosuefF8qgIuvz6A8sd a1ZqdWS5wS+T789afOHtSWMCn4BFtbMM9Tl+0w8VHbtL4VVRiSQBAjhA8Mk1It2Ztu 1Rtxw9fAjdpcu3lhKfs5j8UJYhflZ6uIxlJrw2Mo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 010/403] neighbour: Annotate access to neigh_parms fields. Date: Fri, 9 Oct 2026 16:06:11 +0200 Message-ID: <20261009140952.360657533@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261009140952.119038291@linuxfoundation.org> References: <20261009140952.119038291@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 35d7c70870338aa6a367b9e4ed528914320b0be0 ] 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 e3804cbebb67 ("net: remove COMPAT_NET_DEV_OPS"), which looks wrong, but probably no one uses HIPPI and RoadRunner. Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20251022054004.2514876-3-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/neighbour.h | 15 ++++++++++++--- net/core/neighbour.c | 17 ++++++----------- net/ipv6/ndisc.c | 8 ++++---- 3 files changed, 22 insertions(+), 18 deletions(-) diff --git a/include/net/neighbour.h b/include/net/neighbour.h index c13c758aca7e0..862e53007fd2e 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -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, diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 6afd6490d7847..ce537eca16409 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -996,8 +996,7 @@ 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)) @@ -1750,8 +1749,7 @@ 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; @@ -1811,8 +1809,7 @@ 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); @@ -2195,7 +2192,7 @@ 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) || @@ -2474,8 +2471,7 @@ 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, @@ -3733,8 +3729,7 @@ 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; } diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 7262356de10d9..73732ca910fca 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -1450,7 +1450,7 @@ 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; } @@ -1951,9 +1951,9 @@ 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); -- 2.53.0