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>

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 5730ba6b1cfaff25f2b9d206722662e1e62b88fc..dccbeb25f70141982160c776f3cc727296def2b7 100644 (file)
--- 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 7182f1419c2a4d4ea1e90ef6857f6af895dd2770..0adc993c211d7a3901f9a0e9ee816e7fddc598cd 100644 (file)
--- 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