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>

1 files changed, 1 insertions, 2 deletions

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;