'RELENG_7_0_0_RELEASE'.

This commit was manufactured to restore the state of the 7.0-RELEASE image.

  The kernel uses two ways to write data on a pipe:
      o  buffered write, for chunks smaller than PIPE_MINDIRECT bytes
      o  direct write, for everything else

  A call to writev(2) may receive struct iov of various size and the
  kernel may have to switch from one solution to the other. Before doing
  this, it must wake reader processes and any select/poll/kqueue up.

  This commit fixes a bug where select/poll/kqueue are not triggered
  when switching from buffered write to direct write. It adds calls to
  pipeselwakeup().

  I give more details on freebsd-arch@:
  http://lists.freebsd.org/pipermail/freebsd-arch/2007-September/006790.html

  This should fix issues with Erlang (lang/erlang) and kqueue.

Reported by:	Rickard Green (Erlang)
Approved by:	re (kensmith)

existing UMA statistics for pipes, and allows us to get rid of both the
per-pipe dtor and two atomic operations per pipe required to maintain
the counter.

- Remove also "MP SAFE" after prior "MPSAFE" pass. (suggested by bde)
- Remove extra blank lines in some cases.
- Add extra blank lines in some cases.
- Remove no-op comments consisting solely of the function name, the word
  "syscall", or the system call name.
- Add punctuation.
- Re-wrap some comments.

This fixes sending data through pipe from the kernel.

Fix suggested by:	rwatson

begun with a repo-copy of mac.h to mac_framework.h.  sys/mac.h now
contains the userspace and user<->kernel API and definitions, with all
in-kernel interfaces moved to mac_framework.h, which is now included
across most of the kernel instead.

This change is the first step in a larger cleanup and sweep of MAC
Framework interfaces in the kernel, and will not be MFC'd.

Obtained from:	TrustedBSD Project
Sponsored by:	SPARTA

- Move sonewconn(), which creates new sockets for incoming connections on
  listen sockets, so that all socket allocate code is together in
  uipc_socket.c.

- Move 'maxsockets' and associated sysctls to uipc_socket.c with the
  socket allocation code.

- Move kern.ipc sysctl node to uipc_socket.c, add a SYSCTL_DECL() for it
  to sysctl.h and remove lots of scattered implementations in various
  IPC modules.

- Sort sodealloc() after soalloc() in uipc_socket.c for dependency order
  reasons.  Statisticize soalloc() and sodealloc() as they are now
  required only in uipc_socket.c, and are internal to the socket
  implementation.

After this change, socket allocation and deallocation is entirely
centralized in one file, and uipc_socket2.c consists entirely of socket
buffer manipulation and default protocol switch functions.

MFC after:	1 month

  hardcoded ENFILES, which is incorrect. pipe_create() can fail due
  to ENOMEM.
- Update manual page, describing ENOMEM return code.

Reviewed by:	arch

Submitted by:	Kostik Belousov <kostikbel at gmail.com> on -current@
Message-ID:	<20051216151016.GE84442@deviant.zoral.local>
MFC After:	3 weeks

- Introducing the possibility of using locks different than mutexes
for the knlist locking. In order to do this, we add three arguments to
knlist_init() to specify the functions to use to lock, unlock and
check if the lock is owned. If these arguments are NULL, we assume
mtx_lock, mtx_unlock and mtx_owned, respectively.

- Using the vnode lock for the knlist locking, when doing kqueue operations
on a vnode. This way, we don't have to lock the vnode while holding a
mutex, in filt_vfsread.

Reviewed by:	jmg
Approved by:	re (scottl), scottl (mentor override)
Pointyhat to:	ssouhlal
Will be happy:	everyone