packet: rollover statistics

Rollover indicates exceptional conditions. Export a counter to inform
socket owners of this state.

If no socket with sufficient room is found, rollover fails. Also count
these events.

Finally, also count when flows are rolled over early thanks to huge
flow detection, to validate its correctness.

Tested:
  Read counters in bench_rollover on all other tests in the patchset

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index 053bd102fbe00a0affd7227359e25c7246de9d7e..d3d715f8c88f6d57c4318dc5b001e8efad2d074f 100644 (file)
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -54,6 +54,7 @@ struct sockaddr_ll {
 #define PACKET_FANOUT                  18
 #define PACKET_TX_HAS_OFF              19
 #define PACKET_QDISC_BYPASS            20
+#define PACKET_ROLLOVER_STATS          21
 
 #define PACKET_FANOUT_HASH             0
 #define PACKET_FANOUT_LB               1
@@ -75,6 +76,12 @@ struct tpacket_stats_v3 {
        unsigned int    tp_freeze_q_cnt;
 };
 
+struct tpacket_rollover_stats {
+       __aligned_u64   tp_all;
+       __aligned_u64   tp_huge;
+       __aligned_u64   tp_failed;
+};
+
 union tpacket_stats_u {
        struct tpacket_stats stats1;
        struct tpacket_stats_v3 stats3;

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8f0156b10f8d49a15009bc570579bb43b397fa96..31d58565726c4d72d48ce105a774901c767ced5e 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1395,7 +1395,7 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f,
                                          unsigned int num)
 {
        struct packet_sock *po, *po_next;
-       unsigned int i, j, room;
+       unsigned int i, j, room = ROOM_NONE;
 
        po = pkt_sk(f->arr[idx]);
 
@@ -1413,6 +1413,9 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f,
                    packet_rcv_has_room(po_next, skb) == ROOM_NORMAL) {
                        if (i != j)
                                po->rollover->sock = i;
+                       atomic_long_inc(&po->rollover->num);
+                       if (room == ROOM_LOW)
+                               atomic_long_inc(&po->rollover->num_huge);
                        return i;
                }
 
@@ -1420,6 +1423,7 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f,
                        i = 0;
        } while (i != j);
 
+       atomic_long_inc(&po->rollover->num_failed);
        return idx;
 }
 
@@ -1554,6 +1558,9 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
                po->rollover = kzalloc(sizeof(*po->rollover), GFP_KERNEL);
                if (!po->rollover)
                        return -ENOMEM;
+               atomic_long_set(&po->rollover->num, 0);
+               atomic_long_set(&po->rollover->num_huge, 0);
+               atomic_long_set(&po->rollover->num_failed, 0);
        }
 
        mutex_lock(&fanout_mutex);
@@ -3584,6 +3591,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
        struct packet_sock *po = pkt_sk(sk);
        void *data = &val;
        union tpacket_stats_u st;
+       struct tpacket_rollover_stats rstats;
 
        if (level != SOL_PACKET)
                return -ENOPROTOOPT;
@@ -3659,6 +3667,15 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
                        ((u32)po->fanout->flags << 24)) :
                       0);
                break;
+       case PACKET_ROLLOVER_STATS:
+               if (!po->rollover)
+                       return -EINVAL;
+               rstats.tp_all = atomic_long_read(&po->rollover->num);
+               rstats.tp_huge = atomic_long_read(&po->rollover->num_huge);
+               rstats.tp_failed = atomic_long_read(&po->rollover->num_failed);
+               data = &rstats;
+               lv = sizeof(rstats);
+               break;
        case PACKET_TX_HAS_OFF:
                val = po->tp_tx_has_off;
                break;

diff --git a/net/packet/internal.h b/net/packet/internal.h
index a9d30a17c714756b6de476fb6448512006162b40..c035d263c1e8d119267633971920106b3bf627f3 100644 (file)
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -89,6 +89,9 @@ struct packet_fanout {
 
 struct packet_rollover {
        int                     sock;
+       atomic_long_t           num;
+       atomic_long_t           num_huge;
+       atomic_long_t           num_failed;
 #define ROLLOVER_HLEN  (L1_CACHE_BYTES / sizeof(u32))
        u32                     history[ROLLOVER_HLEN] ____cacheline_aligned;
 } ____cacheline_aligned_in_smp;