Skip to content

Commit

Permalink
net: bridge: mcast: make sure querier port/address updates are consis…
Browse files Browse the repository at this point in the history 
…tent

Use a sequence counter to make sure port/address updates can be read
consistently without requiring the bridge multicast_lock. We need to
zero out the port and address when the other querier has expired and
we're about to select ourselves as querier. br_multicast_read_querier
will be used later when dumping querier state. Updates are done only
with the multicast spinlock and softirqs disabled, while reads are done
from process context and from softirqs (due to notifications).

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
Nikolay Aleksandrov authored and David S. Miller committed Aug 14, 2021
1 parent bb18ef8 commit 67b746f
Show file tree
Hide file tree
Showing 2 changed files with 54 additions and 21 deletions.
74 changes: 53 additions & 21 deletions net/bridge/br_multicast.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1659,11 +1659,38 @@ static void __br_multicast_send_query(struct net_bridge_mcast *brmctx,
}
}

static void br_multicast_read_querier(const struct bridge_mcast_querier *querier,
struct bridge_mcast_querier *dest)
{
unsigned int seq;

memset(dest, 0, sizeof(*dest));
do {
seq = read_seqcount_begin(&querier->seq);
dest->port_ifidx = querier->port_ifidx;
memcpy(&dest->addr, &querier->addr, sizeof(struct br_ip));
} while (read_seqcount_retry(&querier->seq, seq));
}

static void br_multicast_update_querier(struct net_bridge_mcast *brmctx,
struct bridge_mcast_querier *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));
write_seqcount_end(&querier->seq);
}

static void br_multicast_send_query(struct net_bridge_mcast *brmctx,
struct net_bridge_mcast_port *pmctx,
struct bridge_mcast_own_query *own_query)
{
struct bridge_mcast_other_query *other_query = NULL;
struct bridge_mcast_querier *querier;
struct br_ip br_group;
unsigned long time;

Expand All @@ -1676,10 +1703,12 @@ static void br_multicast_send_query(struct net_bridge_mcast *brmctx,

if (pmctx ? (own_query == &pmctx->ip4_own_query) :
(own_query == &brmctx->ip4_own_query)) {
querier = &brmctx->ip4_querier;
other_query = &brmctx->ip4_other_query;
br_group.proto = htons(ETH_P_IP);
#if IS_ENABLED(CONFIG_IPV6)
} else {
querier = &brmctx->ip6_querier;
other_query = &brmctx->ip6_other_query;
br_group.proto = htons(ETH_P_IPV6);
#endif
Expand All @@ -1688,6 +1717,13 @@ static void br_multicast_send_query(struct net_bridge_mcast *brmctx,
if (!other_query || timer_pending(&other_query->timer))
return;

/* we're about to select ourselves as querier */
if (!pmctx && querier->port_ifidx) {
struct br_ip zeroip = {};

br_multicast_update_querier(brmctx, querier, 0, &zeroip);
}

__br_multicast_send_query(brmctx, pmctx, NULL, NULL, &br_group, false,
0, NULL);

Expand Down Expand Up @@ -2830,9 +2866,9 @@ static int br_ip6_multicast_mld2_report(struct net_bridge_mcast *brmctx,

static bool br_ip4_multicast_select_querier(struct net_bridge_mcast *brmctx,
struct net_bridge_mcast_port *pmctx,
__be32 saddr)
struct br_ip *saddr)
{
struct net_bridge_port *port = pmctx ? pmctx->port : NULL;
int port_ifidx = pmctx ? pmctx->port->dev->ifindex : 0;

if (!timer_pending(&brmctx->ip4_own_query.timer) &&
!timer_pending(&brmctx->ip4_other_query.timer))
Expand All @@ -2841,43 +2877,38 @@ static bool br_ip4_multicast_select_querier(struct net_bridge_mcast *brmctx,
if (!brmctx->ip4_querier.addr.src.ip4)
goto update;

if (ntohl(saddr) <= ntohl(brmctx->ip4_querier.addr.src.ip4))
if (ntohl(saddr->src.ip4) <= ntohl(brmctx->ip4_querier.addr.src.ip4))
goto update;

return false;

update:
brmctx->ip4_querier.addr.src.ip4 = saddr;

/* update protected by general multicast_lock by caller */
if (port)
brmctx->ip4_querier.port_ifidx = port->dev->ifindex;
br_multicast_update_querier(brmctx, &brmctx->ip4_querier, port_ifidx,
saddr);

return true;
}

#if IS_ENABLED(CONFIG_IPV6)
static bool br_ip6_multicast_select_querier(struct net_bridge_mcast *brmctx,
struct net_bridge_mcast_port *pmctx,
struct in6_addr *saddr)
struct br_ip *saddr)
{
struct net_bridge_port *port = pmctx ? pmctx->port : NULL;
int port_ifidx = pmctx ? pmctx->port->dev->ifindex : 0;

if (!timer_pending(&brmctx->ip6_own_query.timer) &&
!timer_pending(&brmctx->ip6_other_query.timer))
goto update;

if (ipv6_addr_cmp(saddr, &brmctx->ip6_querier.addr.src.ip6) <= 0)
if (ipv6_addr_cmp(&saddr->src.ip6,
&brmctx->ip6_querier.addr.src.ip6) <= 0)
goto update;

return false;

update:
brmctx->ip6_querier.addr.src.ip6 = *saddr;

/* update protected by general multicast_lock by caller */
if (port)
brmctx->ip6_querier.port_ifidx = port->dev->ifindex;
br_multicast_update_querier(brmctx, &brmctx->ip6_querier, port_ifidx,
saddr);

return true;
}
Expand Down Expand Up @@ -3084,7 +3115,7 @@ br_ip4_multicast_query_received(struct net_bridge_mcast *brmctx,
struct br_ip *saddr,
unsigned long max_delay)
{
if (!br_ip4_multicast_select_querier(brmctx, pmctx, saddr->src.ip4))
if (!br_ip4_multicast_select_querier(brmctx, pmctx, saddr))
return;

br_multicast_update_query_timer(brmctx, query, max_delay);
Expand All @@ -3099,7 +3130,7 @@ br_ip6_multicast_query_received(struct net_bridge_mcast *brmctx,
struct br_ip *saddr,
unsigned long max_delay)
{
if (!br_ip6_multicast_select_querier(brmctx, pmctx, &saddr->src.ip6))
if (!br_ip6_multicast_select_querier(brmctx, pmctx, saddr))
return;

br_multicast_update_query_timer(brmctx, query, max_delay);
Expand All @@ -3119,7 +3150,7 @@ static void br_ip4_multicast_query(struct net_bridge_mcast *brmctx,
struct igmpv3_query *ih3;
struct net_bridge_port_group *p;
struct net_bridge_port_group __rcu **pp;
struct br_ip saddr;
struct br_ip saddr = {};
unsigned long max_delay;
unsigned long now = jiffies;
__be32 group;
Expand Down Expand Up @@ -3199,7 +3230,7 @@ static int br_ip6_multicast_query(struct net_bridge_mcast *brmctx,
struct mld2_query *mld2q;
struct net_bridge_port_group *p;
struct net_bridge_port_group __rcu **pp;
struct br_ip saddr;
struct br_ip saddr = {};
unsigned long max_delay;
unsigned long now = jiffies;
unsigned int offset = skb_transport_offset(skb);
Expand Down Expand Up @@ -3677,7 +3708,6 @@ static void br_multicast_query_expired(struct net_bridge_mcast *brmctx,
if (query->startup_sent < brmctx->multicast_startup_query_count)
query->startup_sent++;

querier->port_ifidx = 0;
br_multicast_send_query(brmctx, NULL, query);
out:
spin_unlock(&brmctx->br->multicast_lock);
Expand Down Expand Up @@ -3735,11 +3765,13 @@ 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);
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);
#endif

timer_setup(&brmctx->ip4_mc_router_timer,
Expand Down
1 change: 1 addition & 0 deletions net/bridge/br_private.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,7 @@ struct bridge_mcast_other_query {
struct bridge_mcast_querier {
struct br_ip addr;
int port_ifidx;
seqcount_t seq;
};

/* IGMP/MLD statistics */
Expand Down

0 comments on commit 67b746f

Please sign in to comment.