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 053bd10..d3d715f8c 100644
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -54,6 +54,7 @@
#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 @@
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 8f0156b..31d5856 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1395,7 +1395,7 @@
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 @@
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 @@
i = 0;
} while (i != j);
+ atomic_long_inc(&po->rollover->num_failed);
return idx;
}
@@ -1554,6 +1558,9 @@
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 @@
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 @@
((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 a9d30a1..c035d26 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -89,6 +89,9 @@
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;