This protects against a race with an upcall in the parent during the
fork which can clobber the parent's tcb before the vm space is copied
in the child. The child then gets a corrupted tcb that is either null
or that points to another thread that doesn't exist in the child (after
a fork, only the fork()ing thread exists in the child).
Reported by: Arno J. Klaassen (arno at heho / snv / jussieu / fr)
child thread goes back to system scope rather than process
scope. This allows an ensuing exec() to actually work.
This change was made a year ago here, but I "forgot" to
commit it :(
Approved by: deischen
MFC after: 3 weeks
they become candidates for reuse. Without this fix, some of the
state from a thread structure's previous incarnation could interfere
with its new one. Specifically, a non-bound thread started as
"suspended" (see pthread_attr_setcreatesuspend_np()) might not get
scheduled at all when resumed, as the "active" flag would be set
spuriously.
Reviewed by: deischen@, davidxu@
MFC after: 1 week
functions in the child after a fork() from a threaded process,
use __sys_setprocmask() rather than setprocmask() to keep our
signal handling sane. Without this fix, signals are essentially
ignored in said child and things such as protection violations
result in an endless busy loop.
Reviewed by: deischen
o Don't reinitialise the atfork() handler list in the child. We
are meant to call the child handler, and on subsequent fork()s
should call all three functions as normal.
o Don't reinitialise the thread specific keyed data in the
child after a fork. Applications may require this for context.
o Reinitialise curthread->tlflags after removing ourselves from
(and reinitialising) the various internal thread lists.
o Reinitialise __malloc_lock in the child after fork() (to balance
our explicitly taking the lock prior to the fork()).
With these changes, it is possible to enable the NOTYET code in
thr_kern.c to allow the use of non-async-safe functions after
fork()ing from a threaded program.
Reviewed by: Daniel Eischen <deischen@freebsd.org>
[_malloc_lock reinitialisation has since been moved to avoid polluting the
!NOTYET code]
signals instead of having more intricate knowledge of thread state
within signal handling.
Simplify signal code because of above (by David Xu).
Use macros for libpthread usage of pthread_cleanup_push() and
pthread_cleanup_pop(). This removes some instances of malloc()
and free() from the semaphore and pthread_once() implementations.
When single threaded and forking(), make sure that the current
thread's signal mask is inherited by the forked thread.
Use private mutexes for libc and libpthread. Signals are
deferred while threads hold private mutexes. This fix also
breaks www/linuxpluginwrapper; a patch that fixes it is at
http://people.freebsd.org/~deischen/kse/linuxpluginwrapper.diff
Fix race condition in condition variables where handling a
signal (pthread_kill() or kill()) may not see a wakeup
(pthread_cond_signal() or pthread_cond_broadcast()).
In collaboration with: davidxu
put DEAD thread on GC list, this closes a race between pthread_join
and thr_cleanup.
2. Introduce a mutex to protect tcb initialization, tls allocation and
deallocation code in rtld seems no lock protection or it is broken,
under stress testing, memory is corrupted.
Reviewed by: deischen
patch partly provided by: deischen
a knob to force process scope threads. If the environment variable
LIBPTHREAD_PROCESS_SCOPE is set, force all threads to be process
scope threads regardless of how the application creates them. If
LIBPTHREAD_SYSTEM_SCOPE is set (forcing system scope threads), it
overrides LIBPTHREAD_PROCESS_SCOPE.
$ # To force system scope threads
$ LIBPTHREAD_SYSTEM_SCOPE=anything threaded_app
$ # To force process scope threads
$ LIBPTHREAD_PROCESS_SCOPE=anything threaded_app
LIBPTHREAD_SYSTEM_SCOPE in the environment.
You can still force libpthread to be built in strictly 1:1 by
adding -DSYSTEM_SCOPE_ONLY to CFLAGS. This is kept for archs
that don't yet support M:N mode.
Requested by: rwatson
Reviewed by: davidxu
1. Add global varible _libkse_debug, debugger uses the varible to identify
libpthread. when the varible is written to non-zero by debugger, libpthread
will take some special action at context switch time, it will check
TMDF_DOTRUNUSER flags, if a thread has the flags set by debugger, it won't
be scheduled, when a thread leaves KSE critical region, thread checks
the flag, if it was set, the thread relinquish CPU.
2. Add pq_first_debug to select a thread allowd to run by debugger.
3. Some names prefixed with _thr are renamed to _thread prefix.
which is allowed to run by debugger.
mode (where the forked thread is the one and only thread and
is marked as system scope), set the system scope flag before
initializing the signal mask. This prevents trying to use
internal locks that haven't yet been initialized.
Reported by: Dan Nelson <dnelson at allantgroup.com>
Reviewed by: davidxu
_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
through branch predict as suggested in INTEL IA32 optimization guide.
2.Allocate siginfo arrary separately to avoid pthread to be allocated at
2K boundary, which hits L1 address alias problem and causes context
switch to be slow down.
3.Simplify context switch code by removing redundant code, code size is
reduced, so it is expected to run faster.
Reviewed by: deischen
Approved by: re (scottl)
signal handling mode, there is no chance to handle the signal, something
must be wrong in the library, just call kse_thr_interrupt to dump its core.
I have the code for a long time, but forgot to commit it.
Aside from the POSIX requirements for pthread_atfork(), when
fork()ing, take the malloc lock to keep malloc state consistent
in the child.
Reviewed by: davidxu
pthread_md.h. This commit only moves the definition; it does not
change it for any of the platforms. This more easily allows 64-bit
architectures (in particular) to pick a slightly larger stack size.
to avoid potential memory leak, also fix a bug in pthread_create, contention
scope should be inherited when PTHREAD_INHERIT_SCHED is set, and also check
right field for PTHREAD_INHERIT_SCHED, scheduling inherit flag is in sched_inherit.
2. Execute hooks registered by atexit() on thread stack but not on scheduler
stack.
3. Simplify some code in _kse_single_thread by calling xxx_destroy functions.
Reviewed by: deischen
yet, so we can protect some locking code from being interrupted by signal
handling. When KSE mode is turned on, reset the thread flag to scope process
except we are running in 1:1 mode which we needn't turn it off.
Also remove some unused member variables in structure kse.
Tested by: deischen
archs that can (or are required to) have per-thread registers.
Tested on i386, amd64; marcel is testing on ia64 and will
have some follow-up commits.
Reviewed by: davidxu
This eliminates ping-ponging of locks, where the idle KSE wakes
up only to find the lock it needs is being held. This gives
little or no gain to M:N mode but greatly speeds up 1:1 mode.
Reviewed & Tested by: davidxu
is system bound thread and when it is blocked, no upcall is generated.
o Add ability to libkse to allow it run in pure 1:1 threading mode,
defining SYSTEM_SCOPE_ONLY in Makefile can turn on this option.
o Eliminate code for installing dummy signal handler for sigwait call.
o Add hash table to find thread.
Reviewed by: deischen
