On 28/09/2021 17:10, Sebastian Andrzej Siewior wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> 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 already checks
> whether the associated lock is held.
>
> 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>
> ---
> net/bridge/br_multicast.c | 6 ++----
> net/bridge/br_private.h | 2 +-
> 2 files changed, 3 insertions(+), 5 deletions(-)
>
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -1677,8 +1677,6 @@ static void br_multicast_update_querier(
> 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_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,
> --- 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 */
>
Thanks for fixing it,
Acked-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxx>
