l2tp: fix locking of 64-bit counters for smp

L2TP uses 64-bit counters but since these are not updated atomically,
we need to make them safe for smp. This patch addresses that.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 0ca9bc3..f1bfae3 100644 (file)
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -330,8 +330,10 @@ static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *sk
        struct sk_buff *skbp;
        struct sk_buff *tmp;
        u32 ns = L2TP_SKB_CB(skb)->ns;
+       struct l2tp_stats *sstats;
 
        spin_lock_bh(&session->reorder_q.lock);
+       sstats = &session->stats;
        skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
                if (L2TP_SKB_CB(skbp)->ns > ns) {
                        __skb_queue_before(&session->reorder_q, skbp, skb);
@@ -339,7 +341,9 @@ static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *sk
                               "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
                               session->name, ns, L2TP_SKB_CB(skbp)->ns,
                               skb_queue_len(&session->reorder_q));
-                       session->stats.rx_oos_packets++;
+                       u64_stats_update_begin(&sstats->syncp);
+                       sstats->rx_oos_packets++;
+                       u64_stats_update_end(&sstats->syncp);
                        goto out;
                }
        }
@@ -356,16 +360,23 @@ static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *
 {
        struct l2tp_tunnel *tunnel = session->tunnel;
        int length = L2TP_SKB_CB(skb)->length;
+       struct l2tp_stats *tstats, *sstats;
 
        /* We're about to requeue the skb, so return resources
         * to its current owner (a socket receive buffer).
         */
        skb_orphan(skb);
 
-       tunnel->stats.rx_packets++;
-       tunnel->stats.rx_bytes += length;
-       session->stats.rx_packets++;
-       session->stats.rx_bytes += length;
+       tstats = &tunnel->stats;
+       u64_stats_update_begin(&tstats->syncp);
+       sstats = &session->stats;
+       u64_stats_update_begin(&sstats->syncp);
+       tstats->rx_packets++;
+       tstats->rx_bytes += length;
+       sstats->rx_packets++;
+       sstats->rx_bytes += length;
+       u64_stats_update_end(&tstats->syncp);
+       u64_stats_update_end(&sstats->syncp);
 
        if (L2TP_SKB_CB(skb)->has_seq) {
                /* Bump our Nr */
@@ -396,6 +407,7 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
 {
        struct sk_buff *skb;
        struct sk_buff *tmp;
+       struct l2tp_stats *sstats;
 
        /* If the pkt at the head of the queue has the nr that we
         * expect to send up next, dequeue it and any other
@@ -403,10 +415,13 @@ static void l2tp_recv_dequeue(struct l2tp_session *session)
         */
 start:
        spin_lock_bh(&session->reorder_q.lock);
+       sstats = &session->stats;
        skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
                if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
-                       session->stats.rx_seq_discards++;
-                       session->stats.rx_errors++;
+                       u64_stats_update_begin(&sstats->syncp);
+                       sstats->rx_seq_discards++;
+                       sstats->rx_errors++;
+                       u64_stats_update_end(&sstats->syncp);
                        PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
                               "%s: oos pkt %u len %d discarded (too old), "
                               "waiting for %u, reorder_q_len=%d\n",
@@ -558,6 +573,7 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
        struct l2tp_tunnel *tunnel = session->tunnel;
        int offset;
        u32 ns, nr;
+       struct l2tp_stats *sstats = &session->stats;
 
        /* The ref count is increased since we now hold a pointer to
         * the session. Take care to decrement the refcnt when exiting
@@ -573,7 +589,9 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
                        PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO,
                               "%s: cookie mismatch (%u/%u). Discarding.\n",
                               tunnel->name, tunnel->tunnel_id, session->session_id);
-                       session->stats.rx_cookie_discards++;
+                       u64_stats_update_begin(&sstats->syncp);
+                       sstats->rx_cookie_discards++;
+                       u64_stats_update_end(&sstats->syncp);
                        goto discard;
                }
                ptr += session->peer_cookie_len;
@@ -642,7 +660,9 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
                        PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
                               "%s: recv data has no seq numbers when required. "
                               "Discarding\n", session->name);
-                       session->stats.rx_seq_discards++;
+                       u64_stats_update_begin(&sstats->syncp);
+                       sstats->rx_seq_discards++;
+                       u64_stats_update_end(&sstats->syncp);
                        goto discard;
                }
 
@@ -661,7 +681,9 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
                        PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING,
                               "%s: recv data has no seq numbers when required. "
                               "Discarding\n", session->name);
-                       session->stats.rx_seq_discards++;
+                       u64_stats_update_begin(&sstats->syncp);
+                       sstats->rx_seq_discards++;
+                       u64_stats_update_end(&sstats->syncp);
                        goto discard;
                }
        }
@@ -715,7 +737,9 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
                         * packets
                         */
                        if (L2TP_SKB_CB(skb)->ns != session->nr) {
-                               session->stats.rx_seq_discards++;
+                               u64_stats_update_begin(&sstats->syncp);
+                               sstats->rx_seq_discards++;
+                               u64_stats_update_end(&sstats->syncp);
                                PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG,
                                       "%s: oos pkt %u len %d discarded, "
                                       "waiting for %u, reorder_q_len=%d\n",
@@ -742,7 +766,9 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
        return;
 
 discard:
-       session->stats.rx_errors++;
+       u64_stats_update_begin(&sstats->syncp);
+       sstats->rx_errors++;
+       u64_stats_update_end(&sstats->syncp);
        kfree_skb(skb);
 
        if (session->deref)
@@ -768,6 +794,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
        int offset;
        u16 version;
        int length;
+       struct l2tp_stats *tstats;
 
        if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb))
                goto discard_bad_csum;
@@ -860,7 +887,10 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb,
 discard_bad_csum:
        LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name);
        UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0);
-       tunnel->stats.rx_errors++;
+       tstats = &tunnel->stats;
+       u64_stats_update_begin(&tstats->syncp);
+       tstats->rx_errors++;
+       u64_stats_update_end(&tstats->syncp);
        kfree_skb(skb);
 
        return 0;
@@ -986,6 +1016,7 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
        struct l2tp_tunnel *tunnel = session->tunnel;
        unsigned int len = skb->len;
        int error;
+       struct l2tp_stats *tstats, *sstats;
 
        /* Debug */
        if (session->send_seq)
@@ -1022,15 +1053,21 @@ static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
                error = ip_queue_xmit(skb, fl);
 
        /* Update stats */
+       tstats = &tunnel->stats;
+       u64_stats_update_begin(&tstats->syncp);
+       sstats = &session->stats;
+       u64_stats_update_begin(&sstats->syncp);
        if (error >= 0) {
-               tunnel->stats.tx_packets++;
-               tunnel->stats.tx_bytes += len;
-               session->stats.tx_packets++;
-               session->stats.tx_bytes += len;
+               tstats->tx_packets++;
+               tstats->tx_bytes += len;
+               sstats->tx_packets++;
+               sstats->tx_bytes += len;
        } else {
-               tunnel->stats.tx_errors++;
-               session->stats.tx_errors++;
+               tstats->tx_errors++;
+               sstats->tx_errors++;
        }
+       u64_stats_update_end(&tstats->syncp);
+       u64_stats_update_end(&sstats->syncp);
 
        return 0;
 }

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 09e4a38..a8c943b 100644 (file)
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -45,6 +45,7 @@ struct l2tp_stats {
        u64                     rx_oos_packets;
        u64                     rx_errors;
        u64                     rx_cookie_discards;
+       struct u64_stats_sync   syncp;
 };
 
 struct l2tp_tunnel;

diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index bc8c334..1dbb977 100644 (file)
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -225,6 +225,8 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 pid, u32 seq, int flags,
        struct nlattr *nest;
        struct sock *sk = NULL;
        struct inet_sock *inet;
+       struct l2tp_stats stats;
+       unsigned int start;
 
        hdr = genlmsg_put(skb, pid, seq, &l2tp_nl_family, flags,
                          L2TP_CMD_TUNNEL_GET);
@@ -242,16 +244,28 @@ static int l2tp_nl_tunnel_send(struct sk_buff *skb, u32 pid, u32 seq, int flags,
        if (nest == NULL)
                goto nla_put_failure;
 
-       if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS, tunnel->stats.tx_packets) ||
-           nla_put_u64(skb, L2TP_ATTR_TX_BYTES, tunnel->stats.tx_bytes) ||
-           nla_put_u64(skb, L2TP_ATTR_TX_ERRORS, tunnel->stats.tx_errors) ||
-           nla_put_u64(skb, L2TP_ATTR_RX_PACKETS, tunnel->stats.rx_packets) ||
-           nla_put_u64(skb, L2TP_ATTR_RX_BYTES, tunnel->stats.rx_bytes) ||
+       do {
+               start = u64_stats_fetch_begin(&tunnel->stats.syncp);
+               stats.tx_packets = tunnel->stats.tx_packets;
+               stats.tx_bytes = tunnel->stats.tx_bytes;
+               stats.tx_errors = tunnel->stats.tx_errors;
+               stats.rx_packets = tunnel->stats.rx_packets;
+               stats.rx_bytes = tunnel->stats.rx_bytes;
+               stats.rx_errors = tunnel->stats.rx_errors;
+               stats.rx_seq_discards = tunnel->stats.rx_seq_discards;
+               stats.rx_oos_packets = tunnel->stats.rx_oos_packets;
+       } while (u64_stats_fetch_retry(&tunnel->stats.syncp, start));
+
+       if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS, stats.tx_packets) ||
+           nla_put_u64(skb, L2TP_ATTR_TX_BYTES, stats.tx_bytes) ||
+           nla_put_u64(skb, L2TP_ATTR_TX_ERRORS, stats.tx_errors) ||
+           nla_put_u64(skb, L2TP_ATTR_RX_PACKETS, stats.rx_packets) ||
+           nla_put_u64(skb, L2TP_ATTR_RX_BYTES, stats.rx_bytes) ||
            nla_put_u64(skb, L2TP_ATTR_RX_SEQ_DISCARDS,
-                       tunnel->stats.rx_seq_discards) ||
+                       stats.rx_seq_discards) ||
            nla_put_u64(skb, L2TP_ATTR_RX_OOS_PACKETS,
-                       tunnel->stats.rx_oos_packets) ||
-           nla_put_u64(skb, L2TP_ATTR_RX_ERRORS, tunnel->stats.rx_errors))
+                       stats.rx_oos_packets) ||
+           nla_put_u64(skb, L2TP_ATTR_RX_ERRORS, stats.rx_errors))
                goto nla_put_failure;
        nla_nest_end(skb, nest);
 
@@ -563,6 +577,8 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 pid, u32 seq, int flags
        struct nlattr *nest;
        struct l2tp_tunnel *tunnel = session->tunnel;
        struct sock *sk = NULL;
+       struct l2tp_stats stats;
+       unsigned int start;
 
        sk = tunnel->sock;
 
@@ -600,19 +616,33 @@ static int l2tp_nl_session_send(struct sk_buff *skb, u32 pid, u32 seq, int flags
            (session->reorder_timeout &&
             nla_put_msecs(skb, L2TP_ATTR_RECV_TIMEOUT, session->reorder_timeout)))
                goto nla_put_failure;
+
        nest = nla_nest_start(skb, L2TP_ATTR_STATS);
        if (nest == NULL)
                goto nla_put_failure;
-       if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS, session->stats.tx_packets) ||
-           nla_put_u64(skb, L2TP_ATTR_TX_BYTES, session->stats.tx_bytes) ||
-           nla_put_u64(skb, L2TP_ATTR_TX_ERRORS, session->stats.tx_errors) ||
-           nla_put_u64(skb, L2TP_ATTR_RX_PACKETS, session->stats.rx_packets) ||
-           nla_put_u64(skb, L2TP_ATTR_RX_BYTES, session->stats.rx_bytes) ||
+
+       do {
+               start = u64_stats_fetch_begin(&session->stats.syncp);
+               stats.tx_packets = session->stats.tx_packets;
+               stats.tx_bytes = session->stats.tx_bytes;
+               stats.tx_errors = session->stats.tx_errors;
+               stats.rx_packets = session->stats.rx_packets;
+               stats.rx_bytes = session->stats.rx_bytes;
+               stats.rx_errors = session->stats.rx_errors;
+               stats.rx_seq_discards = session->stats.rx_seq_discards;
+               stats.rx_oos_packets = session->stats.rx_oos_packets;
+       } while (u64_stats_fetch_retry(&session->stats.syncp, start));
+
+       if (nla_put_u64(skb, L2TP_ATTR_TX_PACKETS, stats.tx_packets) ||
+           nla_put_u64(skb, L2TP_ATTR_TX_BYTES, stats.tx_bytes) ||
+           nla_put_u64(skb, L2TP_ATTR_TX_ERRORS, stats.tx_errors) ||
+           nla_put_u64(skb, L2TP_ATTR_RX_PACKETS, stats.rx_packets) ||
+           nla_put_u64(skb, L2TP_ATTR_RX_BYTES, stats.rx_bytes) ||
            nla_put_u64(skb, L2TP_ATTR_RX_SEQ_DISCARDS,
-                       session->stats.rx_seq_discards) ||
+                       stats.rx_seq_discards) ||
            nla_put_u64(skb, L2TP_ATTR_RX_OOS_PACKETS,
-                       session->stats.rx_oos_packets) ||
-           nla_put_u64(skb, L2TP_ATTR_RX_ERRORS, session->stats.rx_errors))
+                       stats.rx_oos_packets) ||
+           nla_put_u64(skb, L2TP_ATTR_RX_ERRORS, stats.rx_errors))
                goto nla_put_failure;
        nla_nest_end(skb, nest);