Should fix bug number 1227

Thanks to Pavel for the original version of this patch.

into home.osdl.org:/home/torvalds/v2.5/linux

into kernel.bkbits.net:/home/davem/sparc-2.5

into kernel.bkbits.net:/home/davem/net-2.5

Harald synced up ipt_REJECT.c from 2.4 route fixes, but it had
changed a fair bit because of the nonlinear fixes.  This repairs it.

1) Copying of tcp header onto stack.
2) ...which also checks length requirement.
3) Skip checksum check: requires linear packet.

Herve Eychenne noted that many ADSL connections get the same
address when the interface comes back up, so some users use SNAT
instead of masquerade.  The answer is that MASQUERADE should only
drop connections when the interface comes up, and then only if the
interface address has actually changed.

- introduction of the struct array 'atm_proc_ents':
  - removal of code duplication in atm_proc_cleanup();
  - removal of code duplication in atm_proc_init();
  - removal of the macros CREATE_SEQ_ENTRY() and CREATE_ENTRY();
  - /proc/net/atm/vcc returns to /proc/net/atm/vc;
- credits at the top of the file;
- replaced proc_dev_atm_operations by proc_atm_dev_ops;
- atm_proc_dev_register: removal of tasteless "fail0/fail1" labels.

seq_file support for /proc/net/atm/lec:
- lec_info(): seq_printf/seq_putc replaces sprintf;
- traversal of the lec structure needs to walk:
  -> the lec interfaces
     -> the tables of arp tables(lec_arp_tables);
        -> the arp tables themselves
     -> the misc tables (lec_arp_empty_ones/lec_no_forward/mcast_fwds)

  Sum up of the call tree:
  atm_lec_seq_start()/atm_lec_seq_next()
  -> atm_lec_get_idx()
     -> atm_lec_itf_walk() (responsible for dev_lec/dev_put handling)
        -> atm_lec_priv_walk() (responsible for lec_priv locking)
           -> atm_lec_arp_walk()
              -> atm_lec_tbl_walk()
           -> atm_lec_misc_walk()
              -> atm_lec_tbl_walk()

  Each of the dedicated functions follows the same convention: return NULL
  as long as the seq_file cursor hasn't been digested (i.e. until < 0).
  Locking is only done when an entry (i.e. a lec_arp_table) is referenced.
  atm_lec_seq_stop()/atm_lec_itf_walk()/atm_lec_priv_walk() are responsible
  for getting this point right.
- module refcounting is done in atm_lec_seq_open()/atm_lec_seq_release();
- atm_lec_info() is removed.

Chas's suggestions applied since last version:
- atm_seq_lec_fops renamed to lec_seq_fops;
- change in state handling: it wasn't correctly set to its reset value
  after a complete interface walk;
- lec_arp_get_status_string() bugfix.

seq_file support for /proc/net/atm/arp:
- svc_addr/atmarp_info(): seq_printf/seq_putc replace sprintf and friends;
- arp_getidx/arp_vcc_walk() take care of the usual seq_file cursor
  positionning: they both return NULL until the cursor has reached its
  position. struct atm_arp_state is updated accordingly;
- arp_seq_{stop/start} are responsible for clip_tbl_hook (un)locking;
- module refcounting is done in arp_seq_open()/arp_seq_release();
- atm_lec_info() is removed.

Chas's suggestions applied since last version:
- atm_arp_xxx renamed to arp_xxx;
- atm_seq_arp_fops renamed to arp_seq_fops.

Chas didn't ask for it but I renamed arp_vc_walk to arp_vcc_walk.

seq_file support for /proc/net/atm/vc:

Same comments as for pvc and svc.

Extra Chas's suggestion applied since last version:
- atm_vc_xxx renamed to vcc_xxx.

seq_file support for /proc/net/atm/svc:

Exactly same comments as pvc. Just s/p/s/

seq_file support for /proc/net/atm/pvc:
- pvc_info(): seq_printf/seq_putc replaces sprintf;
- atm_pvc_info() removal;
- the vc helpers (vcc__seq_xxx) do the remaining work.

Chas's suggestions applied since last version:
- atm_pvc_xxx renamed to pvc_xxx
- atm_seq_pvc_fops renamed to pvc_seq_fops

Helpers for seq_file conversion of proc/atm/{pvc/svc/vc}:
- struct vcc_state keeps
  1) the struct sock from which the current struct atm_vcc is deduced
  2) the family to which must belong the vcc (PF_ATM{SVC/PVC/any})
  3) the availability of clip module
- vcc_seq{start/stop} are responsible for vcc_sklist locking
- __vcc_seq_open and vcc_seq_release take care of get/put for the clip module.

Chas's suggestions applied since last version:
- atm_vc_xxx renamed to vcc_xxx
- atm_vc_common_seq_open renamed  __vcc_seq_open (future name clashes
  avoidance)

seq_file conversion for proc/atm/devices:
- code inspired from seq_file use in net/core/dev.c;
- atm_dev_lock taken/released in atm_dev_seq_{start/stop};
- add a helper CREATE_SEQ_ENTRY() similar to CREATE_ENTRY() (both are removed
  once conversion is done).
- atm_dev_seq_{start/stop/next} done in net/atm/resource.[ch] to ease
  future handling of atm_devs and locking structure (per Chas suggestion)