net: Fix 'Re: PACKET_TX_RING: packet size is too long'

Currently PACKET_TX_RING forces certain amount of every frame to remain
unused. This probably originates from an early version of the
PACKET_TX_RING patch that in fact used the extra space when the (since
removed) CONFIG_PACKET_MMAP_ZERO_COPY option was enabled. The current
code does not make any use of this extra space.

This patch removes the extra space reservation and lets userspace make
use of the full frame size.

Signed-off-by: Gabor Gombas <gombasg@sztaki.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 4 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 1238949e66a9..48b18dad6763 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -982,10 +982,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
                 goto out_put;
 
         size_max = po->tx_ring.frame_size
-                - sizeof(struct skb_shared_info)
-                - po->tp_hdrlen
-                - LL_ALLOCATED_SPACE(dev)
-                - sizeof(struct sockaddr_ll);
+                - (po->tp_hdrlen - sizeof(struct sockaddr_ll));
 
         if (size_max > dev->mtu + reserve)
                 size_max = dev->mtu + reserve;