net: Allow skb_recycle_check to be done in stages

skb_recycle_check resets the skb if it's eligible for recycling.
However, there are times when a driver might want to optionally
manipulate the skb data with the skb before resetting the skb,
but after it has determined eligibility.  We do this by splitting the
eligibility check from the skb reset, creating two inline functions to
accomplish that task.

Signed-off-by: Andy Fleming <afleming@freescale.com>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: do not take an additional reference in skb_frag_set_page

I audited all of the callers in the tree and only one of them (pktgen) expects
it to do so. Taking this reference is pretty obviously confusing and error
prone.

In particular I looked at the following commits which switched callers of
(__)skb_frag_set_page to the skb paged fragment api:

6a930b9f163d7e6d9ef692e05616c4ede65038ec cxgb3: convert to SKB paged frag API.
5dc3e196ea21e833128d51eb5b788a070fea1f28 myri10ge: convert to SKB paged frag API.
0e0634d20dd670a89af19af2a686a6cce943ac14 vmxnet3: convert to SKB paged frag API.
86ee8130a46769f73f8f423f99dbf782a09f9233 virtionet: convert to SKB paged frag API.
4a22c4c919c201c2a7f4ee09e672435a3072d875 sfc: convert to SKB paged frag API.
18324d690d6a5028e3c174fc1921447aedead2b8 cassini: convert to SKB paged frag API.
b061b39e3ae18ad75466258cf2116e18fa5bbd80 benet: convert to SKB paged frag API.
b7b6a688d217936459ff5cf1087b2361db952509 bnx2: convert to SKB paged frag API.
804cf14ea5ceca46554d5801e2817bba8116b7e5 net: xfrm: convert to SKB frag APIs
ea2ab69379a941c6f8884e290fdd28c93936a778 net: convert core to skb paged frag APIs

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: use TCP_INIT_CWND in tcp_fixup_sndbuf()

Initial cwnd being 10 (TCP_INIT_CWND) instead of 3, change
tcp_fixup_sndbuf() to get more than 16384 bytes (sysctl_tcp_wmem[1]) in
initial sk_sndbuf

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: constify skbuff and Qdisc elements

Preliminary patch before tcp constification

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Conflicts:
	include/net/sch_generic.h
tcp: use TCP_DEFAULT_INIT_RCVWND in tcp_fixup_rcvbuf()

Since commit 356f039822b (TCP: increase default initial receive
window.), we allow sender to send 10 (TCP_DEFAULT_INIT_RCVWND) segments.

Change tcp_fixup_rcvbuf() to reflect this change, even if no real change
is expected, since sysctl_tcp_rmem[1] = 87380 and this value
is bigger than tcp_fixup_rcvbuf() computed rcvmem (~23720)

Note: Since commit 356f039822b limited default window to maximum of
10*1460 and 2*MSS, we use same heuristic in this patch.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: remove unused tcp_fin() parameters

tcp_fin() only needs socket pointer, we can remove skb and th params.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>