netdev - [PATCH net-next 6/8] ipv6: annotate data-races around sysctl.ip6_rt_gc

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Message-ID: <20260115094141.3124990-7-edumazet@google.com>
Date: Thu, 15 Jan 2026 09:41:39 +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: Simon Horman <horms@...nel.org>, David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 6/8] ipv6: annotate data-races around sysctl.ip6_rt_gc_interval

Add READ_ONCE() on lockless reads of net->ipv6.sysctl.ip6_rt_gc_interval

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/ip6_fib.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 2111af022d946d0b9e1a35abdcbac39cbe00f921..174d38c70ac454ac4bd2399a4567862e887150e3 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1374,14 +1374,14 @@ static void fib6_start_gc(struct net *net, struct fib6_info *rt)
 	if (!timer_pending(&net->ipv6.ip6_fib_timer) &&
 	    (rt->fib6_flags & RTF_EXPIRES))
 		mod_timer(&net->ipv6.ip6_fib_timer,
-			  jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
+			  jiffies + READ_ONCE(net->ipv6.sysctl.ip6_rt_gc_interval));
 }
 
 void fib6_force_start_gc(struct net *net)
 {
 	if (!timer_pending(&net->ipv6.ip6_fib_timer))
 		mod_timer(&net->ipv6.ip6_fib_timer,
-			  jiffies + net->ipv6.sysctl.ip6_rt_gc_interval);
+			  jiffies + READ_ONCE(net->ipv6.sysctl.ip6_rt_gc_interval));
 }
 
 static void __fib6_update_sernum_upto_root(struct fib6_info *rt,
@@ -2413,6 +2413,7 @@ static void fib6_gc_all(struct net *net, struct fib6_gc_args *gc_args)
 void fib6_run_gc(unsigned long expires, struct net *net, bool force)
 {
 	struct fib6_gc_args gc_args;
+	int ip6_rt_gc_interval;
 	unsigned long now;
 
 	if (force) {
@@ -2421,8 +2422,8 @@ void fib6_run_gc(unsigned long expires, struct net *net, bool force)
 		mod_timer(&net->ipv6.ip6_fib_timer, jiffies + HZ);
 		return;
 	}
-	gc_args.timeout = expires ? (int)expires :
-			  net->ipv6.sysctl.ip6_rt_gc_interval;
+	ip6_rt_gc_interval = READ_ONCE(net->ipv6.sysctl.ip6_rt_gc_interval);
+	gc_args.timeout = expires ? (int)expires : ip6_rt_gc_interval;
 	gc_args.more = 0;
 
 	fib6_gc_all(net, &gc_args);
@@ -2431,8 +2432,7 @@ void fib6_run_gc(unsigned long expires, struct net *net, bool force)
 
 	if (gc_args.more)
 		mod_timer(&net->ipv6.ip6_fib_timer,
-			  round_jiffies(now
-					+ net->ipv6.sysctl.ip6_rt_gc_interval));
+			  round_jiffies(now + ip6_rt_gc_interval));
 	else
 		timer_delete(&net->ipv6.ip6_fib_timer);
 	spin_unlock_bh(&net->ipv6.fib6_gc_lock);
-- 
2.52.0.457.g6b5491de43-goog