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ipv6: mcast: annotate igmp6 timer expiry race

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/proc/net/igmp6 walks IPv6 multicast memberships under RCU and reads
mca_work.timer.expires to print the remaining multicast timer. The
delayed-work timer can be updated concurrently.

Annotate the intentional lockless procfs snapshot with READ_ONCE().

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260609081113.7613-3-sigefriedhyy@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Yuyang Huang 2026-06-09 17:11:13 +09:00 committed by Jakub Kicinski
parent d0dc208808
commit 1ea2f885a7
1 changed files with 2 additions and 1 deletions
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3
net/ipv6/mcast.c
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@ -2984,6 +2984,7 @@ static int igmp6_mc_seq_show(struct seq_file *seq, void *v)
struct ifmcaddr6 *im = (struct ifmcaddr6 *)v;
struct igmp6_mc_iter_state *state = igmp6_mc_seq_private(seq);
unsigned int mca_flags = READ_ONCE(im->mca_flags);
unsigned long expires = READ_ONCE(im->mca_work.timer.expires);
seq_printf(seq,
"%-4d %-15s %pi6 %5d %08X %ld\n",
@ -2991,7 +2992,7 @@ static int igmp6_mc_seq_show(struct seq_file *seq, void *v)
&im->mca_addr,
READ_ONCE(im->mca_users), mca_flags,
(mca_flags & MAF_TIMER_RUNNING) ?
jiffies_to_clock_t(im->mca_work.timer.expires - jiffies) : 0);
jiffies_to_clock_t(expires - jiffies) : 0);
return 0;
}