Commit e4faaf65 authored Jan 22, 2026 by Eric Dumazet Committed by Jakub Kicinski Jan 25, 2026

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 <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20260122172247.2429403-1-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 05413022

include/linux/inetdevice.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 */

net/ipv4/igmp.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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