Create a bit to signal that a napi_disable() is in progress.

This sets up infrastructure such that net_rx_action() can generically
break out of the ->poll() loop on a NAPI context that has a pending
napi_disable() yet is being bombed with packets (and thus would
otherwise poll endlessly and not allow the napi_disable() to finish).

Now, what napi_disable() does is first set the NAPI_STATE_DISABLE bit
(to indicate that a disable is pending), then it polls for the
NAPI_STATE_SCHED bit, and once the NAPI_STATE_SCHED bit is acquired
the NAPI_STATE_DISABLE bit is cleared.  Here, the test_and_set_bit()
provides the necessary memory barrier between the various bitops.

napi_schedule_prep() now tests for a pending disable as it's first
action and won't try to obtain the NAPI_STATE_SCHED bit if a disable
is pending.

As a result, we can remove the netif_running() check in
netif_rx_schedule_prep() because the NAPI disable pending state serves
this purpose.  And, it does so in a NAPI centric manner which is what
we really want.

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

It is pointless, because everything that can make a device go away
will do a napi_disable() first.

The main impetus behind this is that now we can legally do a NAPI
completion in generic code like net_rx_action() which a following
changeset needs to do.  net_rx_action() can only perform actions
in NAPI centric ways, because there may be a one to many mapping
between NAPI contexts and network devices (SKY2 is one example).

We also want to get rid of this because it's an extra atomic in the
NAPI paths, and also because it is one of the last instances where the
NAPI interfaces care about net devices.

The one remaining netdev detail the NAPI stuff cares about is the
netif_running() check which will be killed off in a subsequent
changeset.

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

Documentation updates for network interfaces.

1. Add doc for netif_napi_add
2. Remove doc for unused returns from netif_rx
3. Add doc for netif_receive_skb

[ Incorporated minor mods from Randy Dunlap -DaveM ]

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

The current napi_disable() uses msleep_interruptible() but doesn't
(and can't) exit in case there's a signal, thus ending up doing a
hot spin without a cpu_relax. Use uninterruptible sleep instead.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove qeth bug caused by commit:
[NET]: Move hardware header operations out of netdevice.

This is the second part of the qeth header_ops patch, since
first patch sent 10/19 has been insufficient.
Nevertheless first patch is still valid and should be kept.

Signed-off-by: Ursula Braun <braunu@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

Many places get the queue_mapping field from skb to pass it to the
netif_subqueue_stopped() which will be 0 in any case.

Make the helper that works with sk_buff

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

* 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/netdev-2.6:
  pcnet32: remove private net_device_stats structure
  vortex_up should initialize "err"
  pcnet32: remove compile warnings in non-napi mode
  pcnet32: fix non-napi packet reception
  fix EMAC driver for proper napi_synchronize API
  sky2: shutdown cleanup
  napi_synchronize: waiting for NAPI
  forcedeth msi bugfix
  gianfar: fix obviously wrong #ifdef CONFIG_GFAR_NAPI placement
  fs_enet: Update for API changes
  gianfar: remove orphan struct.
  forcedeth: fix rx-work condition in nv_rx_process_optimized() too

[ This is kernel bugzilla 9174 "linux-2.6.23-git11 kernel panic" ]

The device in question is an IPv6-over-IPv4 tunnel, which doesn't have
any header_ops, so the crash happens in dev_parse_header when
dereferencing them.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Some drivers with shared NAPI need a synchronization barrier.
Also suggested by Benjamin Herrenschmidt for EMAC.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>