Under DDOS, we want to be able to increment tp_drops without
touching the spinlock. This will help readers to drain
the receive queue slightly faster :/
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
net/packet/af_packet.c | 20 +++++++++++---------
net/packet/internal.h | 1 +
2 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index
a0564855ed9dca4be37f70ed81c6dee1b38aca39..2d499679811af53886ce0c8a1cdd74cd73107eac
100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -758,7 +758,7 @@ static void prb_close_block(struct tpacket_kbdq_core *pkc1,
struct tpacket_hdr_v1 *h1 = &pbd1->hdr.bh1;
struct sock *sk = &po->sk;
- if (po->stats.stats3.tp_drops)
+ if (atomic_read(&po->tp_drops))
status |= TP_STATUS_LOSING;
last_pkt = (struct tpacket3_hdr *)pkc1->prev;
@@ -2128,10 +2128,8 @@ static int packet_rcv(struct sk_buff *skb, struct
net_device *dev,
drop_n_acct:
is_drop_n_account = true;
- spin_lock(&sk->sk_receive_queue.lock);
- po->stats.stats1.tp_drops++;
+ atomic_inc(&po->tp_drops);
atomic_inc(&sk->sk_drops);
- spin_unlock(&sk->sk_receive_queue.lock);
drop_n_restore:
if (skb_head != skb->data && skb_shared(skb)) {
@@ -2265,7 +2263,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct
net_device *dev,
* Anyways, moving it for V1/V2 only as V3 doesn't need this
* at packet level.
*/
- if (po->stats.stats1.tp_drops)
+ if (atomic_read(&po->tp_drops))
status |= TP_STATUS_LOSING;
}
@@ -2381,9 +2379,9 @@ static int tpacket_rcv(struct sk_buff *skb, struct
net_device *dev,
return 0;
drop_n_account:
- is_drop_n_account = true;
- po->stats.stats1.tp_drops++;
spin_unlock(&sk->sk_receive_queue.lock);
+ atomic_inc(&po->tp_drops);
+ is_drop_n_account = true;
sk->sk_data_ready(sk);
kfree_skb(copy_skb);
@@ -3879,6 +3877,7 @@ static int packet_getsockopt(struct socket *sock, int
level, int optname,
void *data = &val;
union tpacket_stats_u st;
struct tpacket_rollover_stats rstats;
+ int drops;
if (level != SOL_PACKET)
return -ENOPROTOOPT;
@@ -3895,14 +3894,17 @@ static int packet_getsockopt(struct socket *sock, int
level, int optname,
memcpy(&st, &po->stats, sizeof(st));
memset(&po->stats, 0, sizeof(po->stats));
spin_unlock_bh(&sk->sk_receive_queue.lock);
+ drops = atomic_xchg(&po->tp_drops, 0);
if (po->tp_version == TPACKET_V3) {
lv = sizeof(struct tpacket_stats_v3);
- st.stats3.tp_packets += st.stats3.tp_drops;
+ st.stats3.tp_drops = drops;
+ st.stats3.tp_packets += drops;
data = &st.stats3;
} else {
lv = sizeof(struct tpacket_stats);
- st.stats1.tp_packets += st.stats1.tp_drops;
+ st.stats1.tp_drops = drops;
+ st.stats1.tp_packets += drops;
data = &st.stats1;
}
diff --git a/net/packet/internal.h b/net/packet/internal.h
index
3bb7c5fb3bff2fd5d91c3d973d006d0cdde29a0b..b5bcff2b7a43b6c9cece329c8fe8b9b546b06cc5
100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -131,6 +131,7 @@ struct packet_sock {
struct net_device __rcu *cached_dev;
int (*xmit)(struct sk_buff *skb);
struct packet_type prot_hook ____cacheline_aligned_in_smp;
+ atomic_t tp_drops ____cacheline_aligned_in_smp;
};
static struct packet_sock *pkt_sk(struct sock *sk)
--
2.22.0.rc2.383.gf4fbbf30c2-goog
