Minor netpoll_send_skb restructuring

Restructure to avoid confusing goto and move some bits out of the
retry loop.
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This fixes an obvious deadlock in the netpoll code.  netpoll_rx takes the
npinfo->rx_lock.  netpoll_rx is also the only caller of arp_reply (through
__netpoll_rx).  As such, it is not necessary to take this lock.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initialize npinfo->rx_flags.  The way it stands now, this will have random
garbage, and so will incur a locking penalty even when an rx_hook isn't
registered and we are not active in the netpoll polling code.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch provides support for registering multiple netpoll clients to the
same network device.  Only one of these clients may register an rx_hook,
however.  In practice, this restriction has not been problematic.  It is
worth mentioning, though, that the current design can be easily extended to
allow for the registration of multiple rx_hooks.

The basic idea of the patch is that the rx_np pointer in the netpoll_info
structure points to the struct netpoll that has rx_hook filled in.  Aside
from this one case, there is no need for a pointer from the struct
net_device to an individual struct netpoll.

A lock is introduced to protect the setting and clearing of the np_rx
pointer.  The pointer will only be cleared upon netpoll client module
removal, and the lock should be uncontested.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces a netpoll_info structure, which the struct net_device
will now point to instead of pointing to a struct netpoll.  The reason for
this is two-fold: 1) fields such as the rx_flags, poll_owner, and poll_lock
should be maintained per net_device, not per netpoll;  and 2) this is a first
step in providing support for multiple netpoll clients to register against the
same net_device.

The struct netpoll is now pointed to by the netpoll_info structure.  As
such, the previous behaviour of the code is preserved.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!