[PATCH 6.19 308/844] ipv4: igmp: annotate data-races around idev->mr_maxdelay

[Sasha Levin]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit e4faaf65a75f650ac4366ddff5dabb826029ca5a ]

idev->mr_maxdelay is read and written locklessly,
add READ_ONCE()/WRITE_ONCE() annotations.

While we are at it, make this field an u32.

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxxx>
Link: https://patch.msgid.link/20260122172247.2429403-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 include/linux/inetdevice.h | 2 +-
 net/ipv4/igmp.c            | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 5730ba6b1cfaf..dccbeb25f7014 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -38,11 +38,11 @@ struct in_device {
 	struct ip_mc_list	*mc_tomb;
 	unsigned long		mr_v1_seen;
 	unsigned long		mr_v2_seen;
-	unsigned long		mr_maxdelay;
 	unsigned long		mr_qi;		/* Query Interval */
 	unsigned long		mr_qri;		/* Query Response Interval */
 	unsigned char		mr_qrv;		/* Query Robustness Variable */
 	unsigned char		mr_gq_running;
+	u32			mr_maxdelay;
 	u32			mr_ifc_count;
 	struct timer_list	mr_gq_timer;	/* general query timer */
 	struct timer_list	mr_ifc_timer;	/* interface change timer */
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 7182f1419c2a4..0adc993c211d7 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -227,7 +227,7 @@ static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
 
 static void igmp_gq_start_timer(struct in_device *in_dev)
 {
-	int tv = get_random_u32_below(in_dev->mr_maxdelay);
+	int tv = get_random_u32_below(READ_ONCE(in_dev->mr_maxdelay));
 	unsigned long exp = jiffies + tv + 2;
 
 	if (in_dev->mr_gq_running &&
@@ -1009,7 +1009,7 @@ static bool igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
 		max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
 		if (!max_delay)
 			max_delay = 1;	/* can't mod w/ 0 */
-		in_dev->mr_maxdelay = max_delay;
+		WRITE_ONCE(in_dev->mr_maxdelay, max_delay);
 
 		/* RFC3376, 4.1.6. QRV and 4.1.7. QQIC, when the most recently
 		 * received value was zero, use the default or statically
-- 
2.51.0