packet: account statistics only in tpacket_stats_u

Currently, packet_sock has a struct tpacket_stats stats member for
TPACKET_V1 and TPACKET_V2 statistic accounting, and with TPACKET_V3
``union tpacket_stats_u stats_u'' was introduced, where however only
statistics for TPACKET_V3 are held, and when copied to user space,
TPACKET_V3 does some hackery and access also tpacket_stats' stats,
although everything could have been done within the union itself.

Unify accounting within the tpacket_stats_u union so that we can
remove 8 bytes from packet_sock that are there unnecessary. Note that
even if we switch to TPACKET_V3 and would use non mmap(2)ed option,
this still works due to the union with same types + offsets, that are
exposed to the user space.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 17 insertions, 23 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ba8309a3e01b..dd5cd49b0e09 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -528,7 +528,7 @@ static void init_prb_bdqc(struct packet_sock *po,
         p1->hdrlen = po->tp_hdrlen;
         p1->version = po->tp_version;
         p1->last_kactive_blk_num = 0;
-        po->stats_u.stats3.tp_freeze_q_cnt = 0;
+        po->stats.stats3.tp_freeze_q_cnt = 0;
         if (req_u->req3.tp_retire_blk_tov)
                 p1->retire_blk_tov = req_u->req3.tp_retire_blk_tov;
         else
@@ -696,7 +696,7 @@ static void prb_close_block(struct tpacket_kbdq_core *pkc1,
         struct tpacket3_hdr *last_pkt;
         struct tpacket_hdr_v1 *h1 = &pbd1->hdr.bh1;
 
-        if (po->stats.tp_drops)
+        if (po->stats.stats3.tp_drops)
                 status |= TP_STATUS_LOSING;
 
         last_pkt = (struct tpacket3_hdr *)pkc1->prev;
@@ -801,7 +801,7 @@ static void prb_freeze_queue(struct tpacket_kbdq_core *pkc,
                                   struct packet_sock *po)
 {
         pkc->reset_pending_on_curr_blk = 1;
-        po->stats_u.stats3.tp_freeze_q_cnt++;
+        po->stats.stats3.tp_freeze_q_cnt++;
 }
 
 #define TOTAL_PKT_LEN_INCL_ALIGN(length) (ALIGN((length), V3_ALIGNMENT))
@@ -1687,7 +1687,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
         nf_reset(skb);
 
         spin_lock(&sk->sk_receive_queue.lock);
-        po->stats.tp_packets++;
+        po->stats.stats1.tp_packets++;
         skb->dropcount = atomic_read(&sk->sk_drops);
         __skb_queue_tail(&sk->sk_receive_queue, skb);
         spin_unlock(&sk->sk_receive_queue.lock);
@@ -1696,7 +1696,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 
 drop_n_acct:
         spin_lock(&sk->sk_receive_queue.lock);
-        po->stats.tp_drops++;
+        po->stats.stats1.tp_drops++;
         atomic_inc(&sk->sk_drops);
         spin_unlock(&sk->sk_receive_queue.lock);
 
@@ -1796,10 +1796,10 @@ 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.tp_drops)
+                if (po->stats.stats1.tp_drops)
                         status |= TP_STATUS_LOSING;
         }
-        po->stats.tp_packets++;
+        po->stats.stats1.tp_packets++;
         if (copy_skb) {
                 status |= TP_STATUS_COPY;
                 __skb_queue_tail(&sk->sk_receive_queue, copy_skb);
@@ -1898,7 +1898,7 @@ drop:
         return 0;
 
 ring_is_full:
-        po->stats.tp_drops++;
+        po->stats.stats1.tp_drops++;
         spin_unlock(&sk->sk_receive_queue.lock);
 
         sk->sk_data_ready(sk, 0);
@@ -3247,8 +3247,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
         struct sock *sk = sock->sk;
         struct packet_sock *po = pkt_sk(sk);
         void *data = &val;
-        struct tpacket_stats st;
-        union tpacket_stats_u st_u;
+        union tpacket_stats_u st;
 
         if (level != SOL_PACKET)
                 return -ENOPROTOOPT;
@@ -3262,22 +3261,18 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
         switch (optname) {
         case PACKET_STATISTICS:
                 spin_lock_bh(&sk->sk_receive_queue.lock);
+                memcpy(&st, &po->stats, sizeof(st));
+                memset(&po->stats, 0, sizeof(po->stats));
+                spin_unlock_bh(&sk->sk_receive_queue.lock);
+
                 if (po->tp_version == TPACKET_V3) {
                         lv = sizeof(struct tpacket_stats_v3);
-                        memcpy(&st_u.stats3, &po->stats,
-                               sizeof(struct tpacket_stats));
-                        st_u.stats3.tp_freeze_q_cnt =
-                                        po->stats_u.stats3.tp_freeze_q_cnt;
-                        st_u.stats3.tp_packets += po->stats.tp_drops;
-                        data = &st_u.stats3;
+                        data = &st.stats3;
                 } else {
                         lv = sizeof(struct tpacket_stats);
-                        st = po->stats;
-                        st.tp_packets += st.tp_drops;
-                        data = &st;
+                        data = &st.stats1;
                 }
-                memset(&po->stats, 0, sizeof(st));
-                spin_unlock_bh(&sk->sk_receive_queue.lock);
+
                 break;
         case PACKET_AUXDATA:
                 val = po->auxdata;
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 650751b9a7ee..c4e4b4561207 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -93,8 +93,7 @@ struct packet_sock {
         /* struct sock has to be the first member of packet_sock */
         struct sock             sk;
         struct packet_fanout    *fanout;
-        struct tpacket_stats    stats;
-        union  tpacket_stats_u  stats_u;
+        union  tpacket_stats_u  stats;
         struct packet_ring_buffer       rx_ring;
         struct packet_ring_buffer       tx_ring;
         int                     copy_thresh;