From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Sun, 26 Sep 2021 17:10:45 +0200
The sequence count bridge_mcast_querier::seq is protected by
net_bridge::multicast_lock but seqcount_init() does not associate the
seqcount with the lock. This leads to a warning on PREEMPT_RT because
preemption is still enabled.
Let seqcount_init() associate the seqcount with lock that protects the
write section. Remove lockdep_assert_held_once() because lockdep checks
for the associated lock.
Fixes: 67b746f94ff39 ("net: bridge: mcast: make sure querier port/address updates are consistent")
Reported-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Tested-by: Mike Galbraith <efault@xxxxxx>
---
I would post this official unless there are objections.
net/bridge/br_multicast.c | 6 ++----
net/bridge/br_private.h | 2 +-
2 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 3523c8c7068fd..f3d751105343c 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1677,8 +1677,6 @@ static void br_multicast_update_querier(struct net_bridge_mcast *brmctx,
int ifindex,
struct br_ip *saddr)
{
- lockdep_assert_held_once(&brmctx->br->multicast_lock);
-
write_seqcount_begin(&querier->seq);
querier->port_ifidx = ifindex;
memcpy(&querier->addr, saddr, sizeof(*saddr));
@@ -3867,13 +3865,13 @@ void br_multicast_ctx_init(struct net_bridge *br,
brmctx->ip4_other_query.delay_time = 0;
brmctx->ip4_querier.port_ifidx = 0;
- seqcount_init(&brmctx->ip4_querier.seq);
+ seqcount_spinlock_init(&brmctx->ip4_querier.seq, &br->multicast_lock);
brmctx->multicast_igmp_version = 2;
#if IS_ENABLED(CONFIG_IPV6)
brmctx->multicast_mld_version = 1;
brmctx->ip6_other_query.delay_time = 0;
brmctx->ip6_querier.port_ifidx = 0;
- seqcount_init(&brmctx->ip6_querier.seq);
+ seqcount_spinlock_init(&brmctx->ip6_querier.seq, &br->multicast_lock);
#endif
timer_setup(&brmctx->ip4_mc_router_timer,
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index b4cef3a97f12b..e8136db44462c 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -82,7 +82,7 @@ struct bridge_mcast_other_query {
struct bridge_mcast_querier {
struct br_ip addr;
int port_ifidx;
- seqcount_t seq;
+ seqcount_spinlock_t seq;
};
/* IGMP/MLD statistics */
--
2.33.0
