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Commit b2d3ea4a authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: switch back to proper tcp_skb_cb size check in tcp_init() 



Revert to the tcp_skb_cb size check that tcp_init() had before commit
b4772ef8 ("net: use common macro for assering skb->cb[] available
size in protocol families"). As related commit 744d5a3e ("net:
move skb->dropcount to skb->cb[]") explains, the
sock_skb_cb_check_size() mechanism was added to ensure that there is
space for dropcount, "for protocol families using it". But TCP is not
a protocol using dropcount, so tcp_init() doesn't need to provision
space for dropcount in the skb->cb[], and thus we can revert to the
older form of the tcp_skb_cb size check. Doing so allows TCP to use 4
more bytes of the skb->cb[] space.

Fixes: b4772ef8 ("net: use common macro for assering skb->cb[] available size in protocol families")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 77879147

net/ipv4/tcp.c

+3 −2
Original line number Diff line number Diff line
@@ -3261,11 +3261,12 @@ static void __init tcp_init_mem(void) 


void __init tcp_init(void)

{

	unsigned long limit;

	int max_rshare, max_wshare, cnt;

	unsigned long limit;

	unsigned int i;



	sock_skb_cb_check_size(sizeof(struct tcp_skb_cb));

	BUILD_BUG_ON(sizeof(struct tcp_skb_cb) >

		     FIELD_SIZEOF(struct sk_buff, cb));



	percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);

	percpu_counter_init(&tcp_orphan_count, 0, GFP_KERNEL);