MFC r312113:

Clean up trailing whitespace

MFC r312112:

Fix -Wunused on gcc 4.9 (x was set but not used)

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix build of kern/subr_unit.c, broken by r300539

Reported by: peter
Pointyhat to: asomers
Sponsored by: Spectra Logic Corp

Add bit_count to the bitstring(3) api

Add a bit_count function, which efficiently counts the number of bits set in
a bitstring.

sys/sys/bitstring.h
tests/sys/sys/bitstring_test.c
share/man/man3/bitstring.3
Add bit_alloc

sys/kern/subr_unit.c
Use bit_count instead of a naive counting loop in check_unrhdr, used
when INVARIANTS are enabled. The userland test runs about 6x faster
in a generic build, or 8.5x faster when built for Nehalem, which has
the POPCNT instruction.

sys/sys/param.h
Bump __FreeBSD_version due to the addition of bit_alloc

UPDATING
Add a note about the ABI incompatibility of the bitstring(3)
changes, as suggested by lidl.

Suggested by: gibbs
Reviewed by: gibbs, ngie
MFC after: 9 days
X-MFC-With: 299090, 300538
Relnotes: yes
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D6255

Add explicit cast to fix mips and powerpc build after r299090

Sponsored by: The FreeBSD Foundation

Improve performance and functionality of the bitstring(3) api

Two new functions are provided, bit_ffs_at() and bit_ffc_at(), which allow
for efficient searching of set or cleared bits starting from any bit offset
within the bit string.

Performance is improved by operating on longs instead of bytes and using
ffsl() for searches within a long. ffsl() is a compiler builtin in both
clang and gcc for most architectures, converting what was a brute force
while loop search into a couple of instructions.

All of the bitstring(3) API continues to be contained in the header file.
Some of the functions are large enough that perhaps they should be uninlined
and moved to a library, but that is beyond the scope of this commit.

sys/sys/bitstring.h:
Convert the majority of the existing bit string implementation from
macros to inline functions.

Properly protect the implementation from inadvertant macro expansion
when included in a user's program by prefixing all private
macros/functions and local variables with '_'.

Add bit_ffs_at() and bit_ffc_at(). Implement bit_ffs() and
bit_ffc() in terms of their "at" counterparts.

Provide a kernel implementation of bit_alloc(), making the full API
usable in the kernel.

Improve code documenation.

share/man/man3/bitstring.3:
Add pre-exisiting API bit_ffc() to the synopsis.

Document new APIs.

Document the initialization state of the bit strings
allocated/declared by bit_alloc() and bit_decl().

Correct documentation for bitstr_size(). The original code comments
indicate the size is in bytes, not "elements of bitstr_t". The new
implementation follows this lead. Only hastd assumed "elements"
rather than bytes and it has been corrected.

etc/mtree/BSD.tests.dist:
tests/sys/Makefile:
tests/sys/sys/Makefile:
tests/sys/sys/bitstring.c:
Add tests for all existing and new functionality.

include/bitstring.h
Include all headers needed by sys/bitstring.h

lib/libbluetooth/bluetooth.h:
usr.sbin/bluetooth/hccontrol/le.c:
Include bitstring.h instead of sys/bitstring.h.

sbin/hastd/activemap.c:
Correct usage of bitstr_size().

sys/dev/xen/blkback/blkback.c
Use new bit_alloc.

sys/kern/subr_unit.c:
Remove hard-coded assumption that sizeof(bitstr_t) is 1. Get rid of
unrb.busy, which caches the number of bits set in unrb.map. When
INVARIANTS are disabled, nothing needs to know that information.
callapse_unr can be adapted to use bit_ffs and bit_ffc instead.
Eliminating unrb.busy saves memory, simplifies the code, and
provides a slight speedup when INVARIANTS are disabled.

sys/net/flowtable.c:
Use the new kernel implementation of bit-alloc, instead of hacking
the old libc-dependent macro.

sys/sys/param.h
Update __FreeBSD_version to indicate availability of new API

Submitted by: gibbs, asomers
Reviewed by: gibbs, ngie
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D6004

Automate the subr_unit test.

Build and install the subr_unit test program originally written by phk, and
run it with the other ATF tests.

tests/sys/kern/Makefile
* Build and install the subr_unit test as a plain test

sys/kern/subr_unit.c
* Reduce the default number of repetitions from 100 to 1, and add a
command-line parser to override it.
* Don't be so noisy by default
* Fix an include problem for the test build

Reviewed by: ngie
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D6038

Move the definition of the struct unrhdr into a separate header file,
to allow embedding the struct. Add init_unrhdr(9) initializer, which
sets up preallocated unrhdr.

Reviewed by: alc
Tested by: pho, bf

Correct double "the the"

Approved by: cperciva
MFC after: 3 days

Fix typos - remove duplicate "the".

PR: bin/154928
Submitted by: Eitan Adler <lists at eitanadler.com>
MFC after: 3 days

Remove redundant high >= 0.

Reported by: rstone

Assert that low and high are >= 0. The allocator doesn't support the
negative range.

Extend the kernel unit number allocator for allocating specific unit
numbers. This change adds a new function alloc_unr_specific() which
returns the requested unit number if it is free. If the number is
already allocated or out of the range, -1 is returned.

Update alloc_unr(9) manual page accordingly and add a MLINK for
alloc_unr_specific(9).

Discussed on: freebsd-hackers

Correct a comment typo.

- Fix compilation of the subr_unit.c user space test program.
- Use %zu for size_t in a few format strings.

Since cdev mutex is after system map mutex in global lock order, free()
shall not be called while holding cdev mutex. devfs_inos unrhdr has cdev as
mutex, thus creating this LOR situation.

Postpone calling free() in kern/subr_unit.c:alloc_unr() and nested functions
until the unrhdr mutex is dropped. Save the freed items on the ppfree list
instead, and provide the clean_unrhdrl() and clean_unrhdr() functions to
clean the list.
Call clean_unrhdrl() after devfs_create() calls immediately before
dropping cdev mutex. devfs_create() is the only user of the alloc_unrl()
in the tree.

Reviewed by: phk
Tested by: Peter Holm
LOR: 80
Approved by: re (kensmith)

Add the witness warning for free_unr. Function could sleep, thus callers
shall not have any non-sleepable locks held.

Submitted by: Hans Petter Selasky <hselasky c2i net>
Approved by: re (kensmith)

Remove debugging printfs.

Reengineer subr_unit

Add support for passing in a mutex. If NULL is passed a global
subr_unit mutex is used.

Add alloc_unrl() which expects the mutex to be held.

Allocating a unit will never sleep as it does not need to allocate
memory.

Cut possible range in half so we can use -1 to mean "out of number".

Collapse first and last runs into the head by means of counters.
This saves memory in the common case(s).

Add placeholder mutex argument to new_unrhdr().

/* -> /*- for copyright notices, minor format tweaks as necessary

Add delete_unrhdr() function.

It will fail fatally if all allocated numbers have not been returned first.

Fix a typo to fix the !DIAGNOSTIC build.

Submitted by: many

Add a new API for allocating unit number (-like) resources.

Allocation is always lowest free unit number.

A mixed range/bitmap strategy for maximum memory efficiency. In
the typical case where no unit numbers are freed total memory usage
is 56 bytes on i386.

malloc is called M_WAITOK but no locking is provided (yet). A bit of
experience will be necessary to determine the best strategy. Hopefully
a "caller provides locking" strategy can be maintained, but that may
require use of M_NOWAIT allocation and failure handling.

A userland test driver is included.