From e4faaf65a75f650ac4366ddff5dabb826029ca5a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 22 Jan 2026 17:22:47 +0000 Subject: [PATCH] ipv4: igmp: annotate data-races around idev->mr_maxdelay 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 Reviewed-by: David Ahern Link: https://patch.msgid.link/20260122172247.2429403-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- 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 -- 2.47.3