Do allow POSIX mqueue unlink privilege inside a jail, as we all all
other POSIX mqueue privileges inside a jail.

Replace custom file descriptor array sleep lock constructed using a mutex
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared

Replace custom file descriptor array sleep lock constructed using a mutex
and flags with an sxlock. This leads to a significant and measurable
performance improvement as a result of access to shared locking for
frequent lookup operations, reduced general overhead, and reduced overhead
in the event of contention. All of these are imported for threaded
applications where simultaneous access to a shared file descriptor array
occurs frequently. Kris has reported 2x-4x transaction rate improvements
on 8-core MySQL benchmarks; smaller improvements can be expected for many
workloads as a result of reduced overhead.

- Generally eliminate the distinction between "fast" and regular
acquisisition of the filedesc lock; the plan is that they will now all
be fast. Change all locking instances to either shared or exclusive
locks.

- Correct a bug (pointed out by kib) in fdfree() where previously msleep()
was called without the mutex held; sx_sleep() is now always called with
the sxlock held exclusively.

- Universally hold the struct file lock over changes to struct file,
rather than the filedesc lock or no lock. Always update the f_ops
field last. A further memory barrier is required here in the future
(discussed with jhb).

- Improve locking and reference management in linux_at(), which fails to
properly acquire vnode references before using vnode pointers. Annotate
improper use of vn_fullpath(), which will be replaced at a future date.

In fcntl(), we conservatively acquire an exclusive lock, even though in
some cases a shared lock may be sufficient, which should be revisited.
The dropping of the filedesc lock in fdgrowtable() is no longer required
as the sxlock can be held over the sleep operation; we should consider
removing that (pointed out by attilio).

Tested by: kris
Discussed with: jhb, kris, attilio, jeff

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Make insmntque() externally visibile and allow it to fail (e.g. during
late stages of unmount). On failure, the vnode is recycled.

Add insmntque1(), to allow for file system specific cleanup when
r

Make insmntque() externally visibile and allow it to fail (e.g. during
late stages of unmount). On failure, the vnode is recycled.

Add insmntque1(), to allow for file system specific cleanup when
recycling vnode on failure.

Change getnewvnode() to no longer call insmntque(). Previously,
embryonic vnodes were put onto the list of vnode belonging to a file
system, which is unsafe for a file system marked MPSAFE.

Change vfs_hash_insert() to no longer lock the vnode. The caller now
has that responsibility.

Change most file systems to lock the vnode and call insmntque() or
insmntque1() after a new vnode has been sufficiently setup. Handle
failed insmntque*() calls by propagating errors to callers, possibly
after some file system specific cleanup.

Approved by: re (kensmith)
Reviewed by: kib
In collaboration with: kib

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Further system call comment cleanup:

- 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 n

Further system call comment cleanup:

- 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.

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Merge posix4/* into normal kernel hierarchy.

Reviewed by: glanced at by jhb
Approved by: silence on -arch@ and -standards@

Sweep kernel replacing suser(9) calls with priv(9) calls, assigning
specific privilege names to a broad range of privileges. These may
require some future tweaking.

Sponsored by: nCircle

Sweep kernel replacing suser(9) calls with priv(9) calls, assigning
specific privilege names to a broad range of privileges. These may
require some future tweaking.

Sponsored by: nCircle Network Security, Inc.
Obtained from: TrustedBSD Project
Discussed on: arch@
Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
Alex Lyashkov <umka at sevcity dot net>,
Skip Ford <skip dot ford at verizon dot net>,
Antoine Brodin <antoine dot brodin at laposte dot net>

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Use mount interlock to protect all changes to mnt_flag and mnt_kern_flag.
This eliminates a race where MNT_UPDATE flag could be lost when nmount()
raced against sync(), sync_fsync() or quotactl().

Change msleep() and tsleep() to not alter the calling thread's priority
if the specified priority is zero. This avoids a race where the calling
thread could read a snapshot of it's current priority,

Change msleep() and tsleep() to not alter the calling thread's priority
if the specified priority is zero. This avoids a race where the calling
thread could read a snapshot of it's current priority, then a different
thread could change the first thread's priority, then the original thread
would call sched_prio() inside msleep() undoing the change made by the
second thread. I used a priority of zero as no thread that calls msleep()
or tsleep() should be specifying a priority of zero anyway.

The various places that passed 'curthread->td_priority' or some variant
as the priority now pass 0.

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Let kernel POSIX timer code and mqueue code to use integer as a resource
handle, the timer_t and mqd_t types will be a pointer which userland
will define it.

Abstract function mqfs_create_node() to create a mqueue node.

Replace selwakeuppri with selwakeup, let scheduler figure out
appropriate thread priority.

Stop fiddling thread priority with msleep, eliminating unnecessary
context switching. This improves performance about 30% on UP machine.

Comment out mqfs_create_link. Inline some small functions.

o Turn on MPSAFE flag for mqueuefs.
o Reuse si_mqd field in siginfo_t, this also gives userland
information about which descriptor is notified.

After reading some documents, I realized SIGEV_NONE != NULL, also
fix code in mqueue_send_notification to handle SIGEV_NONE.

Handle SIGEV_NONE, if notification is SIGEV_NONE, error status and
return status will be set, but no notification will be registered.
Increase hard limit of maxmsg to 100, so posixtestsuite ports can

Handle SIGEV_NONE, if notification is SIGEV_NONE, error status and
return status will be set, but no notification will be registered.
Increase hard limit of maxmsg to 100, so posixtestsuite ports can run.

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1. Cleanup including.
2. Set configuration value for CTL_P1003_1B_MESSAGE_PASSING.

1. Check if message priority is less than MQ_PRIO_MAX.
2. Use getnanotime instead of getnanouptime.
3. Don't free message in _mqueue_send, mqueue_send will free it.

Last step to make mq_notify conform to POSIX standard, If the process
has successfully attached a notification request to the message queue
via a queue descriptor, file closing should remove the atta

Last step to make mq_notify conform to POSIX standard, If the process
has successfully attached a notification request to the message queue
via a queue descriptor, file closing should remove the attachment.

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Fix a stupid compiler warining, remove a redundant line.

Change filesystem name from mqueue to mqueuefs for style consistent.

Suggested by: rwatson

Bring in experimental kernel support for POSIX message queue.