Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Remove hacks to allow libkse to export its symbols in the LIBTHREAD_1_0
version namespace which was needed before the library version was
bumped.

WARNS=3'ify.

Repo copy libpthreads to libkse.
This introduces the WITHOUT_LIBKSE nob,
and changes WITHOUT_LIBPTHREADS to mean with neither threading libs.
Approved by: re(kensmith)

Add compatibility symbol maps. libpthread (.so.1 and .so.2)
used LIBTHREAD_1_0 as its version definition, but now needs
to define its symbols in the same namespace used by libc.
The compatibility hooks allows you to use libraries and
binaries built and linked to libpthread before libc was
built with symbol versioning. The shims can be removed if
libpthread is given a version bump.

Reviewed by: davidxu

Rename _thr_enter_cancellation_point to _thr_cancel_enter, rename
_thr_leave_cancellation_point to _thr_cancel_leave, add a parameter
to _thr_cancel_leave to indicate whether cancellation point should be
checked, this gives us an option to not check cancallation point if
a syscall successfully returns to avoid any leaks, current I have
creat(), open() and fcntl(F_DUPFD) to not check cancellation point
after they sucessfully returned.

Replace some members in structure kse with bit flags to same some
memory.

Conditionally compile THR_ASSERT to nothing if _PTHREAD_INVARIANTS is
not defined.

Inline some small functions in thr_cancel.c.

Use __predict_false in thr_kern.c for some executed only once code.

Reviewd by: deischen

Revamp libpthread so that it has a chance of working in an SMP
environment. This includes support for multiple KSEs and KSEGs.

The ability to create more than 1 KSE via pthread_setconcurrency()
is in the works as well as support for PTHREAD_SCOPE_SYSTEM threads.
Those should come shortly.

There are still some known issues which davidxu and I are working
on, but it'll make it easier for us by committing what we have.

This library now passes all of the ACE tests that libc_r passes
with the exception of one. It also seems to work OK with KDE
including konqueror, kwrite, etc. I haven't been able to get
mozilla to run due to lack of java plugin, so I'd be interested
to see how it works with that.

Reviewed by: davidxu

Make libpthread KSE aware.

Reviewed by: deischen, julian
Approved by: -arch

Make the changes needed for libpthread to compile in its new home.
The new libpthread will provide POSIX threading support using KSE.
These files were previously repo-copied from src/lib/libc_r.

Reviewed by: deischen
Approved by: -arch

Make these functions cancellation points like they should be:
poll(2), readv(2), select(2), wait4(2), writev(2).

PR: bin/37658
Reviewed by: deischen
MFC after: 1 week

To be consistent, use the __weak_reference macro from <sys/cdefs.h>
instead of #pragma weak to create weak definitions.

Suggested by: bde

Add weak definitions for wrapped system calls. In general:

_foo - wrapped system call
foo - weak definition to _foo

and for cancellation points:

_foo - wrapped system call
__foo - enter cancellation point, call _foo(), leave
cancellation point
foo - weak definition to __foo

Change use of global _thread_run to call a function to get the
currently running thread.

Make all pthread_foo functions weak definitions to _pthread_foo,
where _pthread_foo is the implementation. This allows an application
to provide its own pthread functions.

Provide slightly different versions of pthread_mutex_lock and
pthread_mutex_init so that we can tell the difference between
a libc mutex and an application mutex. Threads holding mutexes
internal to libc should never be allowed to exit, call signal
handlers, or cancel.

Approved by: -arch

Use __strong_reference() instead of __weak_reference() to assure that the
weak symbols of the same name are not used.

Simplify sytem call renaming. Instead of _foo() <-- _libc_foo <-- foo(),
just use _foo() <-- foo(). In the case of a libpthread that doesn't do
call conversion (such as linuxthreads and our upcoming libpthread), this
is adequate. In the case of libc_r, we still need three names, which are
now _thread_sys_foo() <-- _foo() <-- foo().

Convert all internal libc usage of: aio_suspend(), close(), fsync(), msync(),
nanosleep(), open(), fcntl(), read(), and write() to _foo() instead of foo().

Remove all internal libc usage of: creat(), pause(), sleep(), system(),
tcdrain(), wait(), and waitpid().

Make thread cancellation fully POSIX-compliant.

Suggested by: deischen

Fix millisecond to nanosecond conversion.

PR: misc/16245

Track libc's three-tier symbol naming. libc_r must currently implement
the _libc_*() entry points and add *() weak aliases. This will all
change for the better when libc_r becomes libpthread.

-Wall and minor style(9) cleanups.

When checking for valid timevals in the wrapped select() and poll()
routines, don't return EINVAL but set errno to EINVAL and return -1.
Added a check in pthread_cond_timedwait for a null timespec pointer.

$Id$ -> $FreeBSD$

Sanity check time structures passed in, return EINVAL like the system
calls do to avoid corrupting the thread library's concept of wakeup
time.

PR: kern/12141
Reviewed by: deischen, eivind

In the words of the author:

o The polling mechanism for I/O readiness was changed from
select() to poll(). In additon, a wrapped version of poll()
is now provided.

o The wrapped select routine now converts each fd_set to a
poll array so that the thread scheduler doesn't have to
perform a bitwise search for selected fds each time file
descriptors are polled for I/O readiness.

o The thread scheduler was modified to use a new queue (_workq)
for threads that need work. Threads waiting for I/O readiness
and spinblocks are added to the work queue in addition to the
waiting queue. This reduces the time spent forming/searching
the array of file descriptors being polled.

o The waiting queue (_waitingq) is now maintained in order of
thread wakeup time. This allows the thread scheduler to
find the nearest wakeup time by looking at the first thread
in the queue instead of searching the entire queue.

o Removed file descriptor locking for select/poll routines. An
application should not rely on the threads library for providing
this locking; if necessary, the application should use mutexes
to protect selecting/polling of file descriptors.

o Retrieve and use the kernel clock rate/resolution at startup
instead of hardcoding the clock resolution to 10 msec (tested
with kernel running at 1000 HZ).

o All queues have been changed to use queue.h macros. These
include the queues of all threads, dead threads, and threads
waiting for file descriptor locks.

o Added reinitialization of the GC mutex and condition variable
after a fork. Also prevented reallocation of the ready queue
after a fork.

o Prevented the wrapped close routine from closing the thread
kernel pipes.

o Initialized file descriptor table for stdio entries at thread
init.

o Provided additional flags to indicate to what queues threads
belong.

o Moved TAILQ initialization for statically allocated mutex and
condition variables to after the spinlock.

o Added dispatching of signals to pthread_kill. Removing the
dispatching of signals from thread activation broke sigsuspend
when pthread_kill was used to send a signal to a thread.

o Temporarily set the state of a thread to PS_SUSPENDED when it
is first created and placed in the list of threads so that it
will not be accidentally scheduled before becoming a member
of one of the scheduling queues.

o Change the signal handler to queue signals to the thread kernel
pipe if the scheduling queues are protected. When scheduling
queues are unprotected, signals are then dequeued and handled.

o Ensured that all installed signal handlers block the scheduling
signal and that the scheduling signal handler blocks all
other signals. This ensures that the signal handler is only
interruptible for and by non-scheduling signals. An atomic
lock is used to decide which instance of the signal handler
will handle pending signals.

o Removed _lock_thread_list and _unlock_thread_list as they are
no longer used to protect the thread list.

o Added missing RCS IDs to modified files.

o Added checks for appropriate queue membership and activity when
adding, removing, and searching the scheduling queues. These
checks add very little overhead and are enabled when compiled
with _PTHREADS_INVARIANTS defined. Suggested and implemented
by Tor Egge with some modification by me.

o Close a race condition in uthread_close. (Tor Egge)

o Protect the scheduling queues while modifying them in
pthread_cond_signal and _thread_fd_unlock. (Tor Egge)

o Ensure that when a thread gets a mutex, the mutex is on that
threads list of owned mutexes. (Tor Egge)

o Set the kernel-in-scheduler flag in _thread_kern_sched_state
and _thread_kern_sched_state_unlock to prevent a scheduling
signal from calling the scheduler again. (Tor Egge)

o Don't use TAILQ_FOREACH macro while searching the waiting
queue for threads in a sigwait state, because a change of
state destroys the TAILQ link. It is actually safe to do
so, though, because once a sigwaiting thread is found, the
loop ends and the function returns. (Tor Egge)

o When dispatching signals to threads, make the thread inherit
the signal deferral flag of the currently running thread.
(Tor Egge)

Submitted by: Daniel Eischen <eischen@vigrid.com> and
Tor Egge <Tor.Egge@fast.no>