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* Instead of using a join queue for each thread, use a single pointer tojasone2001-05-201-9/+1
| | | | | | | | | | | keep track of a joiner. POSIX only supports a single joiner, so this simplification is acceptable. At the same time, make sure to mark a joined thread as detached so that its resources can be freed. Reviewed by: deischen PR: 24345
* Move the check for a pending signals to after the thread has beendeischen2001-05-041-0/+3
| | | | | | | | | | | | | | | placed in any scheduling queue(s). The process of dispatching signals to a thread can change its state which will attempt to add or remove the thread from any scheduling queue to which it belongs. This can break some assertions if the thread isn't in the queue(s) implied by its state. When adding dispatching a pending signal to a thread, be sure to remove the signal from the threads set of pending signals. PR: 27035 Tested by: brian MFC in: 1 week
* Correct a race condition where it was possible for a signaleddeischen2001-03-091-2/+8
| | | | | | | | thread to become stranded and not placed in the run queue. MFC Candidate Reported by: tegge
* Remove (int) file descriptor locking. It should be up to thedeischen2001-02-111-5/+0
| | | | | | | | | | | | | application to provide locking for I/O operations. This doesn't break any of my tests, but the old behavior can be restored by compiling with _FDLOCKS_ENABLED. This will eventually be removed when it is obvious it does not cause any problems. Remove most of flockfile implementation, with the exception of flockfile_debug. Make error messages more informational (submitted by Mike Heffner <spock@techfour.net>, who's now known as mikeh@FreeBSD.org).
* Add weak definitions for wrapped system calls. In general:deischen2001-01-241-20/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | _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
* Change a "while {}" loop to a "do {} while" to allow it to bedeischen2000-11-201-0/+4
| | | | | | | | | | | | | executed at least once, fixing pthread_mutex_lock() for recursive mutex lock attempts. Correctly set a threads signal mask while it is executing a signal handler. The mask should be the union of its current mask, the signal being handled, and the mask from the signal action. Reported by: Dan Nelson <dnelson@emsphone.com> MFC Candidate
* When entering the scheduler from the signal handler, telldeischen2000-11-141-1/+1
| | | | | | | | | | | the kernel to (re)use the alternate signal stack. In this case, we don't return normally from the signal handler, so the kernel still thinks we are using the signal stack. The fixes a nasty bug where the signal handler can start fiddling with the stack of a thread while the handler is actually running on the same stack. MFC candidate
* Don't needlessly poll file descriptors when there are nodeischen2000-11-091-297/+146
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | file descriptors needing to be polled (Doh!). Reported by Dan Nelson <dnelson@emsphone.com>. Don't install and start the scheduling timer until the first thread is created. This prevents the overhead of having a periodic scheduling signal in a single threaded program. Reported by Dan Nelson <dnelson@emsphone.com>. Allow builtin longjmps out of application installed signal handlers without the need perform any post-handler cleanup: o Change signal handling to save the threads interrupted context on the stack. The threads current context is now always stored in the same place (in the pthread). If and when a signal handler returns, the interrupted context is copied back to the storage area in the pthread. o Before calling invoking a signal handler for a thread, back the thread out of any internal waiting queues (mutex, CV, join, etc) to which it belongs. Rework uthread_info.c a bit to make it easier to change the format of a thread dump. Use an alternal signal stack for the thread library's signal handler. This allows us to fiddle with the main threads stack without fear of it being in use. Reviewed by: jasone
* Make pthread_kill() know about temporary signal handlers installeddeischen2000-10-251-29/+119
| | | | | | | by sigwait(). This prevents a signal from being sent to the process when there are no application installed signal handlers. Correct a typo in sigwait (foo -> foo[i]).
* We use ___setjmp (non-signal saving) to setup a signal frame. Whendeischen2000-10-221-1/+1
| | | | | | | adding a signal frame to a thread, be sure to label the context correctly so we don't restore an uninitialized process mask. Reported by: kimc@W8HD.ORG and Andrey Rouskol <anry@sovintel.ru>
* Implement zero system call thread switching. Performance ofdeischen2000-10-131-413/+829
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | thread switches should be on par with that under scheduler activations. o Timing is achieved through the use of a fixed interval timer (ITIMER_PROF) to count scheduling ticks instead of retrieving the time-of-day upon every thread switch and calculating elapsed real time. o Polling for I/O readiness is performed once for each scheduling tick instead of every thread switch. o The non-signal saving/restoring versions of setjmp/longjmp are used to save and restore thread contexts. This may allow the removal of _THREAD_SAFE macros from setjmp() and longjmp() - needs more investigation. Change signal handling so that signals are handled in the context of the thread that is receiving the signal. When signals are dispatched to a thread, a special signal handling frame is created on top of the target threads stack. The frame contains the threads saved state information and a new context in which the thread can run. The applications signal handler is invoked through a wrapper routine that knows how to restore the threads saved state and unwind to previous frames. Fix interruption of threads due to signals. Some states were being improperly interrupted while other states were not being interrupted. This should fix several PRs. Signal handlers, which are invoked as a result of a process signal (not by pthread_kill()), are now called with the code (or siginfo_t if SA_SIGINFO was set in sa_flags) and sigcontext_t as received from the process signal handler. Modify the search for a thread to which a signal is delivered. The search algorithm is now: o First thread found in sigwait() with signal in wait mask. o First thread found sigsuspend()'d on the signal. o Current thread if signal is unmasked. o First thread found with signal unmasked. Collapse machine dependent support into macros defined in pthread_private.h. These should probably eventually be moved into separate MD files. Change the range of settable priorities to be compliant with POSIX (0-31). The threads library uses higher priorities internally for real-time threads (not yet implemented) and threads executing signal handlers. Real-time threads and threads running signal handlers add 64 and 32, respectively, to a threads base priority. Some other small changes and cleanups. PR: 17757 18559 21943 Reviewed by: jasone
* Fix pthread_suspend_np/pthread_resume_np. For the record, suspending adeischen2000-03-151-6/+8
| | | | | | | | | | | | | | thread waiting on an event (I/O, condvar, etc) will, when resumed using pthread_resume_np, return with EINTR. For example, suspending and resuming a thread blocked on read() will not requeue the thread for the read, but will return -1 with errno = EINTR. If the suspended thread is in a critical region, the thread is suspended as soon as it leaves the critical region. Fix a bogon in pthread_kill() where a signal was being delivered twice to threads waiting in sigwait(). Reported by (suspend/resume bug): jdp Reviewed by: jasone
* Do signal deferral for pthread_kill() as it was done in the old days.jasone2000-01-201-20/+3
| | | | Submitted by: deischen
* Implement continuations to correctly handle [sig|_]longjmp() inside of ajasone2000-01-191-17/+195
| | | | | | | | | | | | | | | | | | | | | | signal handler. Explicitly check for jumps to anywhere other than the current stack, since such jumps are undefined according to POSIX. While we're at it, convert thread cancellation to use continuations, since it's cleaner than the original cancellation code. Avoid delivering a signal to a thread twice. This was a pre-existing bug, but was likely unexposed until these other changes were made. Defer signals generated by pthread_kill() so that they can be delivered on the appropriate stack. deischen claims that this is unnecessary, which is likely true, but without this change, pthread_kill() can cause undefined priority queue states and/or PANICs in [sig|_]longjmp(), so I'm leaving this in for now. To compile this code out and exercise the bug, define the _NO_UNDISPATCH cpp macro. Defining _PTHREADS_INVARIANTS as well will cause earlier crashes. PR: kern/14685 Collaboration with: deischen
* Don't wakeup threads when there is a process signal and no installeddeischen1999-12-281-23/+37
| | | | | | | | handler. Thread-to-thread signals (pthread_signal) are treated differently than process signals; a pthread_signal can wakeup a blocked thread if a signal handler is not installed for that signal. Found by: ACE tests
* Fixes for signal handling:deischen1999-12-171-51/+197
| | | | | | | | | | | | | | o Don't call signal handlers with the signal handler access lock held. o Remove pending signals before calling signal handlers. If pending signals were not removed prior to handling them, invocation of the handler could cause the handler to be called more than once for the same signal. Found by: JB o When SIGCHLD arrives, wake up all threads in PS_WAIT_WAIT (wait4). PR: bin/15328 Reviewed by: jasone
* Change signal handling to conform to POSIX specified semantics.deischen1999-12-041-23/+65
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before this change, a signal was delivered to each thread that didn't have the signal masked. Signals also improperly woke up threads waiting on I/O. With this change, signals are now handled in the following way: o If a thread is waiting in a sigwait for the signal, then the thread is woken up. o If no threads are sigwait'ing on the signal and a thread is in a sigsuspend waiting for the signal, then the thread is woken up. o In the case that no threads are waiting or suspended on the signal, then the signal is delivered to the first thread we find that has the signal unmasked. o If no threads are waiting or suspended on the signal, and no threads have the signal unmasked, then the signal is added to the process wide pending signal set. The signal will be delivered to the first thread that unmasks the signal. If there is an installed signal handler, it is only invoked if the chosen thread was not in a sigwait. In the case that multiple threads are waiting or suspended on a signal, or multiple threads have the signal unmasked, we wake up/deliver the signal to the first thread we find. The above rules still apply. Reported by: Scott Hess <scott@avantgo.com> Reviewed by: jb, jasone
* sigset_t change (part 5 of 5)marcel1999-09-291-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ----------------------------- Most of the userland changes are in libc. For both the alpha and the i386 setjmp has been changed to accomodate for the new sigset_t. Internally, libc is mostly rewritten to use the new syscalls. The exception is in compat-43/sigcompat.c The POSIX thread library has also been rewritten to use the new sigset_t. Except, that it currently only handles NSIG signals instead of the maximum _SIG_MAXSIG. This should not be a problem because current applications don't use any signals higher than NSIG. There are version bumps for the following libraries: libdialog libreadline libc libc_r libedit libftpio libss These libraries either a) have one of the modified structures visible in the interface, or b) use sigset_t internally and may cause breakage if new binaries are used against libraries that don't have the sigset_t change. This not an immediate issue, but will be as soon as applications start using the new range to its fullest. NOTE: libncurses already had an version bump and has not been given one now. NOTE: doscmd is a real casualty and has been disconnected for the moment. Reconnection will eventually happen after doscmd has been fixed. I'm aware that being the last one to touch it, I'm automaticly promoted to being maintainer. According to good taste this means that I will receive a badge which either will be glued or mechanically stapled, drilled or otherwise violently forced onto me :-) NOTE: pcvt/vttest cannot be compiled with -traditional. The change cause sys/types to be included along the way which contains the const and volatile modifiers. I don't consider this a solution, but more a workaround.
* $Id$ -> $FreeBSD$peter1999-08-281-1/+1
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* Add RCS IDs to those files without them.deischen1999-08-051-2/+2
| | | | | | | Fix copyrights (s/REGENTS/AUTHOR). Suggested by: tg Approved by: jb
* In the words of the author:jb1999-06-201-91/+119
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* [ The author's description... ]jb1999-03-231-12/+39
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | o Runnable threads are now maintained in priority queues. The implementation requires two things: 1.) The priority queues must be protected during insertion and removal of threads. Since the kernel scheduler must modify the priority queues, a spinlock for protection cannot be used. The functions _thread_kern_sched_defer() and _thread_kern_sched_undefer() were added to {un}defer kernel scheduler activation. 2.) A thread (active) priority change can be performed only when the thread is removed from the priority queue. The implementation uses a threads active priority when inserting it into the queue. A by-product is that thread switches are much faster. A separate queue is used for waiting and/or blocked threads, and it is searched at most 2 times in the kernel scheduler when there are active threads. It should be possible to reduce this to once by combining polling of threads waiting on I/O with the loop that looks for timed out threads and the minimum timeout value. o Functions to defer kernel scheduler activation were added. These are _thread_kern_sched_defer() and _thread_kern_sched_undefer() and may be called recursively. These routines do not block the scheduling signal, but latch its occurrence. The signal handler will not call the kernel scheduler when the running thread has deferred scheduling, but it will be called when running thread undefers scheduling. o Added support for _POSIX_THREAD_PRIORITY_SCHEDULING. All the POSIX routines required by this should now be implemented. One note, SCHED_OTHER, SCHED_FIFO, and SCHED_RR are required to be defined by including pthread.h. These defines are currently in sched.h. I modified pthread.h to include sched.h but don't know if this is the proper thing to do. o Added support for priority protection and inheritence mutexes. This allows definition of _POSIX_THREAD_PRIO_PROTECT and _POSIX_THREAD_PRIO_INHERIT. o Added additional error checks required by POSIX for mutexes and condition variables. o Provided a wrapper for sigpending which is marked as a hidden syscall. o Added a non-portable function as a debugging aid to allow an application to monitor thread context switches. An application can install a routine that gets called everytime a thread (explicitly created by the application) gets context switched. The routine gets passed the pthread IDs of the threads that are being switched in and out. Submitted by: Dan Eischen <eischen@vigrid.com> Changes by me: o Added a PS_SPINBLOCK state to deal with the priority inversion problem most often (I think) seen by threads calling malloc/free/realloc. o Dispatch signals to the running thread directly rather than at a context switch to avoid the situation where the switch never occurs.
* Implementation of an additional state called SIGWAIT (with the previousjb1998-09-301-44/+42
| | | | | | one renamed to SIGSUSPEND) to fix sigwait(). Submitted by: Daniel M. Eischen <eischen@vigrid.com>
* Removed unused variables.alex1998-09-071-4/+0
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* Back out most of the last commit. It created problems with sigpause.jb1998-08-261-26/+1
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* Fix for sigwait problem.jb1998-08-251-1/+26
| | | | | Submitted by: Daniel M. Eischen <eischen@vigrid.com> PR: misc/7039
* Don't allow a SIGCHLD to wake up a thread if the process has the defaultjb1998-06-171-6/+9
| | | | | signal handler installed for SIGCHLD. The ACE MT_SOCK_Test was hanging as the result of being interrupted when it didn't expect to be.
* If a thread is waiting on a child process to complete, the SIGCHLDjb1998-06-171-1/+20
| | | | | | signal can arrive before the thread is woken from it's wait4. In this case, don't return an EINTR, just set the thread state to running and the wait4 wrapper will loop and get the exit status of the process.
* Remove SA_RESTART from the signal dispatch in user-space since thisjb1998-06-101-92/+39
| | | | seems to be tripping up a lot of applications.
* Implement compile time debug support instead of tracking file name andjb1998-06-091-10/+10
| | | | | | | line number every time a file descriptor is locked. This looks like a big change but it isn't. It should reduce the size of libc_r and make it run slightly faster.
* I got the last commit back to front.jb1998-06-061-3/+3
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* Fix the signal behaviour for internal states which set the threadjb1998-06-051-6/+51
| | | | | state to running despite the SA_RESTART flag which is really just for syscalls.
* Don't restart a syscall when a SIGCHLD is received by a thread waitingjb1998-05-311-1/+6
| | | | on a child process.
* Change signal model to match POSIX (i.e. one set of signal handlersjb1998-04-291-72/+227
| | | | | | | | | | | | | | | | | | | | for the process, not a separate set for each thread). By default, the process now only has signal handlers installed for SIGVTALRM, SIGINFO and SIGCHLD. The thread kernel signal handler is installed for other signals on demand. This means that SIG_IGN and SIG_DFL processing is now left to the kernel, not the thread kernel. Change the signal dispatch to no longer use a signal thread, and call the signal handler using the stack of the thread that has the signal pending. Change the atomic lock method to use test-and-set asm code with a yield if blocked. This introduces separate locks for each type of object instead of blocking signals to prevent a context switch. It was this blocking of signals that caused the performance degradation the people have noted. This is a *big* change!
* Submitted by: John Birrelljulian1997-02-051-1/+1
| | | | uthreads update from the author.
* Submitted by: John Birrell <cimaxp1!jb@werple.net.au>julian1996-08-201-5/+44
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here are the diffs for libc_r to get it one step closer to P1003.1c These make most of the thread/mutex/condvar structures opaque to the user. There are three functions which have been renamed with _np suffixes because they are extensions to P1003.1c (I did them for JAVA, which needs to suspend/resume threads and also start threads suspended). I've created a new header (pthread_np.h) for the non-POSIX stuff. The egrep tags stuff in /usr/src/lib/libc_r/Makefile that I uncommented doesn't work. I think its best to delete it. I don't think libc_r needs tags anyway, 'cause most of the source is in libc which does have tags. also: Here's the first batch of man pages for the thread functions. The diff to /usr/src/lib/libc_r/Makefile removes some stuff that was inherited from /usr/src/lib/libc/Makefile that should only be done with libc. also: I should have sent this diff with the pthread(3) man page. It allows people to type make -DWANT_LIBC_R world to get libc_r built with the rest of the world. I put this in the pthread(3) man page. The default is still not to build libc_r. also: The diff attached adds a pthread(3) man page to /usr/src/share/man/man3. The idea is that without libc_r installed, this man page will give people enough info to know that they have to build libc_r.
* Reviewed by: julianjulian1996-01-221-0/+128
Submitted by: john birrel One version of the pthreads library another will follow with differnt actions under some cases.. not QUITE complete
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