netdev - [PATCH net-next 1/4] tcp_metrics: add missing barriers on delete

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Message-ID: <20230922220356.3739090-2-edumazet@google.com>
Date: Fri, 22 Sep 2023 22:03:53 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: Neal Cardwell <ncardwell@...gle.com>, Yuchung Cheng <ycheng@...gle.com>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 1/4] tcp_metrics: add missing barriers on delete

When removing an item from RCU protected list, we must prevent
store-tearing, using rcu_assign_pointer() or WRITE_ONCE().

Fixes: 04f721c671656 ("tcp_metrics: Rewrite tcp_metrics_flush_all")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp_metrics.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index c196759f1d3bd8cb16479522e936bd95091f89b2..4bfa2fb27de5481ca3d1300d7e7b2c80d1577a31 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -908,7 +908,7 @@ static void tcp_metrics_flush_all(struct net *net)
 			match = net ? net_eq(tm_net(tm), net) :
 				!refcount_read(&tm_net(tm)->ns.count);
 			if (match) {
-				*pp = tm->tcpm_next;
+				rcu_assign_pointer(*pp, tm->tcpm_next);
 				kfree_rcu(tm, rcu_head);
 			} else {
 				pp = &tm->tcpm_next;
@@ -949,7 +949,7 @@ static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 		if (addr_same(&tm->tcpm_daddr, &daddr) &&
 		    (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 		    net_eq(tm_net(tm), net)) {
-			*pp = tm->tcpm_next;
+			rcu_assign_pointer(*pp, tm->tcpm_next);
 			kfree_rcu(tm, rcu_head);
 			found = true;
 		} else {
-- 
2.42.0.515.g380fc7ccd1-goog