When a driver writer calls this, they generally expect that
all previous stores and modifications they've made will be
visible before netif_poll_enable() executes, so ensure this.

Noticed by Ben H.

Signed-off-by: David S. Miller <davem@davemloft.net>

hh_lock was converted from rwlock to seqlock by Stephen.

To have a 100% benefit of this change, I suggest to place read mostly fields
of hh_cache in a separate cache line, because hh_refcnt may be changed quite
frequently on some busy machines.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The hard header cache is in the main output path, so using
seqlock instead of reader/writer lock should reduce overhead.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

[acme@newtoy net-2.6.20]$ pahole net/ipv4/tcp.o hh_cache
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/linux/netdevice.h:190 */
struct hh_cache {
        struct hh_cache *          hh_next;              /*     0     4 */
        atomic_t                   hh_refcnt;            /*     4     4 */
        __be16                     hh_type;              /*     8     2 */

        /* XXX 2 bytes hole, try to pack */

        int                        hh_len;               /*    12     4 */
        int                        (*hh_output)();       /*    16     4 */
        rwlock_t                   hh_lock;              /*    20    36 */
        long unsigned int          hh_data[24];          /*    56    96 */
}; /* size: 152, sum members: 150, holes: 1, sum holes: 2 */

[acme@newtoy net-2.6.20]$ find net -name "*.[ch]" | xargs grep 'hh_len.\+=' | sort -u
net/atm/br2684.c:               hh->hh_len = PADLEN + ETH_HLEN;
net/ethernet/eth.c:     hh->hh_len = ETH_HLEN;
net/ipv4/ipconfig.c:    int hh_len = LL_RESERVED_SPACE(dev);
net/ipv4/ip_output.c:   hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
net/ipv4/ip_output.c:   int hh_len = LL_RESERVED_SPACE(dev);
net/ipv4/netfilter.c:   hh_len = (*pskb)->dst->dev->hard_header_len;
net/ipv4/raw.c: hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
net/ipv6/ip6_output.c:  hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
net/ipv6/netfilter/ip6t_REJECT.c:       hh_len = (dst->dev->hard_header_len + 15)&~15;
net/ipv6/raw.c: hh_len = LL_RESERVED_SPACE(rt->u.dst.dev);
[acme@newtoy net-2.6.20]$

[acme@newtoy net-2.6.20]$ find include -name "*.h" | xargs grep 'define ETH_HLEN'
include/linux/if_ether.h:#define ETH_HLEN       14              /* Total octets in header.       */

        (((dev)->hard_header_len&~(HH_DATA_MOD - 1)) + HH_DATA_MOD)

[acme@newtoy net-2.6.20]$ pahole net/ipv4/tcp.o net_device | grep hard_header_len
        short unsigned int         hard_header_len;      /*   106     2 */
[acme@newtoy net-2.6.20]$

So I think we're safe in turning hh_len an u16, end result:

[acme@newtoy net-2.6.20]$ codiff -sV /tmp/tcp.o.before net/ipv4/tcp.o
/pub/scm/linux/kernel/git/acme/net-2.6.20/net/ipv4/tcp.c:
  struct hh_cache |   -4
    hh_len;
     from: int                   /*    12(0)     4(0) */
     to:   u16                   /*    10(0)     2(0) */
 1 struct changed
[acme@newtoy net-2.6.20]$

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

Throughout the TCP/DCCP (and tunnelling) code, it often happens that the
return code of a transmit function needs to be tested against NET_XMIT_CN
which is a value that does not indicate a strict error condition.

This patch uses a macro for these recurring situations which is consistent
with the already existing macro net_xmit_errno, saving on duplicated code.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

This patch contains the scheduled removal of the frame diverter.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAX_HEADER is either set to LL_MAX_HEADER or LL_MAX_HEADER + 48, and
this is controlled by a set of CONFIG_* ifdef tests.

It is trying to use LL_MAX_HEADER + 48 when any of the tunnels are
enabled which set hard_header_len like this:

dev->hard_header_len = LL_MAX_HEADER + sizeof(struct xxx);

The correct set of tunnel drivers which do this are:

ipip
ip_gre
ip6_tunnel
sit

so make the ifdef test match.

Noticed by Patrick McHardy and with help from Herbert Xu.

Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>