Improve bufring impl:
- Remove unused br_prod_bufs member
- Fixup r241037: buf_ring pads br_prod_* and br_cons_* members at 128
  bytes, assuming a fixed cache line size for all the architectures.
  However, the above mentioned revision broke the padding.
  Use explicit padding to the CACHE_LINE_SIZE on the members that
  mark the initial new padded sections. Of course, the padding is not
  important for performance reasons in the DEBUG_BUFRING case, leaving
  br_cons members to share the cache line with br_lock.
- Fixup r244732: by removing incorrectly added membar in
  buf_ring_dequeue_sc() where surrounding locking shoud be enough.
- Drastically reduce the number of membar used (pratically reverting
  r244732) by switching rmb() in buf_ring_dequeue_mc() and wmb() in
  buf_ring_enqueue() to be complete barriers.  This, along with
  br_prod_bufs departure, should fix ordering issues as explained in
  the provided comments.

This patch is not targeted for MFC.

Sponsored by:	EMC / Isilon storage division
Reviewed by:	glebius


git-svn-id: svn://svn.freebsd.org/base/head@244774 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
gcc: avoid generating negative values to DW_AT_byte_size.

There is a bug in gcc (GCC/35998) where dwarf reports
sizes of unsigned -1 (0xffffffff).

On NetBSD this generated a faulty CTF entry which then
caused a segfault in ctfmerge. The issue was worked
around in NetBSD's Dtrace but since the issue originated
in gcc, it seems reasonable to fix it here.

Upstream gcc has been slow to react to this issue and
the author that submitted the patch is not interested
in licensing the change to us, so I did an independent
workaround for the issue.

MFC after:	1 week


git-svn-id: svn://svn.freebsd.org/base/head@244776 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Do not leave parts of the new group uninitialized in gr_dup().

Submitted by:	Christoph Mallon <christoph.mallon@gmx.de>
Reported by:	pjd


git-svn-id: svn://svn.freebsd.org/base/head@244777 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
malloc() sets errno to ENOMEM already.

Submitted by:	Christoph Mallon <christoph.mallon@gmx.de>


git-svn-id: svn://svn.freebsd.org/base/head@244778 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
errno = ENOMEM was supposed to be removed not return (NULL);

Submitted by:	gcooper


git-svn-id: svn://svn.freebsd.org/base/head@244779 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Simplify pointing dst after the end of all the gr_mem pointers in newgr

Submitted by:	pjd
Reviewed by:	db


git-svn-id: svn://svn.freebsd.org/base/head@244780 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Use DEVMETHOD_END.

MFC after:	2 weeks


git-svn-id: svn://svn.freebsd.org/base/head@244781 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add DEVICE_IDENTIFY method for wbwd(4), required on most of recent
Supermicro motherboards.

Tested on X8STi and X8DTH boards.

Sponsored by:	iXsystems, Inc.
MFC after:	2 weeks


git-svn-id: svn://svn.freebsd.org/base/head@244787 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Fix typo in comment.

Submitted by:	Christoph Mallon <christoph.mallon@gmx.de>


git-svn-id: svn://svn.freebsd.org/base/head@244790 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Fix wording nit.

PR:		174787
Submitted by:	Cody Rank
MFC after:	3 days


git-svn-id: svn://svn.freebsd.org/base/head@244791 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
gcc: avoid generating negative values to DW_AT_byte_size.

The previous change was actually a NOP because size is
unsigned and compilers are dumb.

Submitted by:	Christoph Mallon
MFC after:	1 week


git-svn-id: svn://svn.freebsd.org/base/head@244792 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Make it possible to atomically resume writes on the mount and account
the write start, by adding a variation of the vfs_write_resume(9)
which accepts flags.

Use the new function to prevent a deadlock between parallel suspension
and snapshotting a UFS mount.  The ffs_snapshot() code performed
vfs_write_resume() followed by vn_start_write() while owning the
snaplock.  If the suspension intervene between resume and
vn_start_write(), the deadlock occured after the suspending thread
tried to lock the snaplock, most typically during the write in the
ffs_copyonwrite().

Reported and tested by:	Andreas Longwitz <longwitz@incore.de>
Reviewed by:	mckusick
MFC after:	2 weeks
X-MFC-note:	make the vfs_write_resume(9) function a macro after the MFC,
	in HEAD


git-svn-id: svn://svn.freebsd.org/base/head@244795 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
It's no longer necessary to explicitly specify isa bus.

MFC after:	2 weeks


git-svn-id: svn://svn.freebsd.org/base/head@244796 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Fix incorrect function name. s/[[:<:]]dialog_clear/f_&/


git-svn-id: svn://svn.freebsd.org/base/head@244797 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Whitespace.


git-svn-id: svn://svn.freebsd.org/base/head@244798 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Allow debug output to be logged to a file (set $debugFile to target pathname)
or both stdout and a file (precede $debugFile pathname with a plus-sign, `+').


git-svn-id: svn://svn.freebsd.org/base/head@244799 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add support for running without a controlling terminal (for example, when
running as an rvalue to a pipe).


git-svn-id: svn://svn.freebsd.org/base/head@244801 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add missing enforcement of height restriction after minor adjustment.


git-svn-id: svn://svn.freebsd.org/base/head@244802 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Comments.


git-svn-id: svn://svn.freebsd.org/base/head@244804 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Test commit to make sure commit mail works after moving the server.

Approved by:	core (implicit)


git-svn-id: svn://svn.freebsd.org/base/head@244822 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f