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Miller" , David Ahern , Eric Dumazet , Ido Schimmel , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH net-next 2/2] ipv6: mcast: annotate igmp6 timer expiry race Date: Fri, 5 Jun 2026 23:57:59 +0900 Message-ID: <20260605145759.59639-3-sigefriedhyy@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260605145759.59639-1-sigefriedhyy@gmail.com> References: <20260605145759.59639-1-sigefriedhyy@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit /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 --- net/ipv6/mcast.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index bd3972730aa0..184e57469086 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -2983,6 +2983,7 @@ 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 long expires = READ_ONCE(im->mca_work.timer.expires); unsigned int mca_flags = READ_ONCE(im->mca_flags); seq_printf(seq, @@ -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; } -- 2.43.0