intention of the POSIX IEEE Std 1003.1TM-2008/Cor 1-2013.
A robust mutex is guaranteed to be cleared by the system upon either
thread or process owner termination while the mutex is held. The next
mutex locker is then notified about inconsistent mutex state and can
execute (or abandon) corrective actions.
The patch mostly consists of small changes here and there, adding
neccessary checks for the inconsistent and abandoned conditions into
existing paths. Additionally, the thread exit handler was extended to
iterate over the userspace-maintained list of owned robust mutexes,
unlocking and marking as terminated each of them.
The list of owned robust mutexes cannot be maintained atomically
synchronous with the mutex lock state (it is possible in kernel, but
is too expensive). Instead, for the duration of lock or unlock
operation, the current mutex is remembered in a special slot that is
also checked by the kernel at thread termination.
Kernel must be aware about the per-thread location of the heads of
robust mutex lists and the current active mutex slot. When a thread
touches a robust mutex for the first time, a new umtx op syscall is
issued which informs about location of lists heads.
The umtx sleep queues for PP and PI mutexes are split between
non-robust and robust.
Somewhat unrelated changes in the patch:
1. Style.
2. The fix for proper tdfind() call use in umtxq_sleep_pi() for shared
pi mutexes.
3. Removal of the userspace struct pthread_mutex m_owner field.
4. The sysctl kern.ipc.umtx_vnode_persistent is added, which controls
the lifetime of the shared mutex associated with a vnode' page.
Reviewed by: jilles (previous version, supposedly the objection was fixed)
Discussed with: brooks, Martin Simmons <martin@lispworks.com> (some aspects)
Tested by: pho
Sponsored by: The FreeBSD Foundation
than silently failing and returning success.
Without this, code calls pthread_once(), receives a return value of
success, and thinks that the passed function has been called.
Approved by: dim (mentor)
for them, two functions _pthread_cancel_enter and _pthread_cancel_leave
are added to let thread enter and leave a cancellation point, it also
makes it possible that other functions can be cancellation points in
libraries without having to be rewritten in libthr.
now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User can either use mmap(MAP_SHARED) + sem_init(pshared=1) or use sem_open()
to initialize a shared semaphore.
Named semaphore uses file system and is located in /tmp directory, and its
file name is prefixed with 'SEMD', so now it is chroot or jail friendly.
In simplist cases, both for named and un-named semaphore, userland code
does not have to enter kernel to reduce/increase semaphore's count.
The semaphore is designed to be crash-safe, it means even if an application
is crashed in the middle of operating semaphore, the semaphore state is
still safely recovered by later use, there is no waiter counter maintained
by userland code.
The main semaphore code is in libc and libthr only has some necessary stubs,
this makes it possible that a non-threaded application can use semaphore
without linking to thread library.
Old semaphore implementation is kept libc to maintain binary compatibility.
The kernel ksem API is no longer used in the new implemenation.
Discussed on: threads@
a feature that libstdc++ depends on to simulate the behavior of libc's
internal '__isthreaded' variable. One benefit of this is that _libc_once()
is now private to _once_stub.c.
Requested by: kan
with the additional property that it is safe for routines in libc to use
in both single-threaded and multi-threaded processes. Multi-threaded
processes use the pthread_once() implementation from the threading library
while single-threaded processes use a simplified "stub" version internal
to libc. The libc stub-version of pthread_once() now also uses the
simplified "stub" version as well instead of being a nop.
Reviewed by: deischen, Matthew Fleming @ Isilon
Suggested by: alc
MFC after: 1 week
the type argument. This is known to fix some pthread_mutexattr_settype()
invocations, especially when it comes to pulseaudio.
Approved by: kib
deischen (threads)
MFC after: 3 days
entries in the table being stubs. While I'm here, add macros to
auto-generate the stubs. A conforming threads library can override
the stub routines by filling in the jump table.
Add some entries to namespace.h and sync un-namespace.h to it.
Also add a comment to remind folks to update un-namespace.h
when changing namespace.h.
* Fix typos in rwlock stubs.
* Add pthread_XXX counterparts to the _pthread_XXX stubs which libraries
like libX11 can use to ensure thread-safety without requiring the use
of a thread library.
Submitted by: Terry Lambert (pthread_cond_broadcast)
Reviewed by: deischen
of calling sigprocmask(). This matches the behaviour of thr_sigsetmask()
on Solaris; _pthread_sigmask_stub was added purely for compatibility
with Solaris (for TI-RPC), so it might as well do the same thing.
This fixes the problem where client RPC calls ignored all signals
for the complete duration of the RPC. This behaviour is currently
necessary in the threaded case due to locking issues, but was never
intended to occur in non-threaded programs.
Reviewed by: deischen
instead of #pragma weak to create weak definitions. This macro is
improperly named, though, since a weak definition is not the same
thing as a weak reference.
Suggested by: bde
associated changes that had to happen to make this possible as well as
bugs fixed along the way.
Bring in required TLI library routines to support this.
Since we don't support TLI we've essentially copied what NetBSD
has done, adding a thin layer to emulate direct the TLI calls
into BSD socket calls.
This is mostly from Sun's tirpc release that was made in 1994,
however some fixes were backported from the 1999 release (supposedly
only made available after this porting effort was underway).
The submitter has agreed to continue on and bring us up to the
1999 release.
Several key features are introduced with this update:
Client calls are thread safe. (1999 code has server side thread
safe)
Updated, a more modern interface.
Many userland updates were done to bring the code up to par with
the recent RPC API.
There is an update to the pthreads library, a function
pthread_main_np() was added to emulate a function of Sun's threads
library.
While we're at it, bring in NetBSD's lockd, it's been far too
long of a wait.
New rpcbind(8) replaces portmap(8) (supporting communication over
an authenticated Unix-domain socket, and by default only allowing
set and unset requests over that channel). It's much more secure
than the old portmapper.
Umount(8), mountd(8), mount_nfs(8), nfsd(8) have also been upgraded
to support TI-RPC and to support IPV6.
Umount(8) is also fixed to unmount pathnames longer than 80 chars,
which are currently truncated by the Kernel statfs structure.
Submitted by: Martin Blapp <mb@imp.ch>
Manpage review: ru
Secure RPC implemented by: wpaul
Add a lock to FILE. flockfile and friends are now implemented
(for the most part) in libc. flockfile_debug is implemented in
libc_r; I suppose it's about time to kill it but will do it in
a future commit.
Fix a potential deadlock in _fwalk in a threaded environment.
A file flag (__SIGN) was added to stdio.h that, when set, tells
_fwalk to ignore it in its walk. This seemed to be needed in
refill.c because each file needs to be locked when flushing.
Add a stub for pthread_self in libc. This is needed by flockfile
which is allowed by POSIX to be recursive.
Make fgetpos() error return value (-1) match man page.
Remove recursive calls to locked functions (stdio); I think I've
got them all, but I may have missed a couple.
A few K&R -> ANSI conversions along with removal of a few instances
of "register".
$Id$ -> $FreeBSD$ in libc/stdio/rget.c
Not objected to: -arch, a few months ago
adding (weak definitions to) stubs for some of the pthread
functions. If the threads library is linked in, the real
pthread functions will pulled in.
Use the following convention for system calls wrapped by the
threads library:
__sys_foo - actual system call
_foo - weak definition to __sys_foo
foo - weak definition to __sys_foo
Change all libc uses of system calls wrapped by the threads
library from foo to _foo. In order to define the prototypes
for _foo(), we introduce namespace.h and un-namespace.h
(suggested by bde). All files that need to reference these
system calls, should include namespace.h before any standard
includes, then include un-namespace.h after the standard
includes and before any local includes. <db.h> is an exception
and shouldn't be included in between namespace.h and
un-namespace.h namespace.h will define foo to _foo, and
un-namespace.h will undefine foo.
Try to eliminate some of the recursive calls to MT-safe
functions in libc/stdio in preparation for adding a mutex
to FILE. We have recursive mutexes, but would like to avoid
using them if possible.
Remove uneeded includes of <errno.h> from a few files.
Add $FreeBSD$ to a few files in order to pass commitprep.
Approved by: -arch
