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author | Ulrich Drepper <drepper@redhat.com> | 1998-03-11 12:42:25 +0000 |
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committer | Ulrich Drepper <drepper@redhat.com> | 1998-03-11 12:42:25 +0000 |
commit | 5afdca0087dad2994ad4fcdfe7f489f4dbcab7b3 (patch) | |
tree | c9c82db2ff92537b921361a02a284b0e18a594b8 /linuxthreads/man/pthread_mutex_init.man | |
parent | 3d76e7784700c20fc222920b2a22baba006daa15 (diff) | |
download | glibc-5afdca0087dad2994ad4fcdfe7f489f4dbcab7b3.tar.gz glibc-5afdca0087dad2994ad4fcdfe7f489f4dbcab7b3.tar.xz glibc-5afdca0087dad2994ad4fcdfe7f489f4dbcab7b3.zip |
LinuxThreads library.
1998-03-11 00:42 Wolfram Gloger <wmglo@dent.med.uni-muenchen.de> * linuxthreads/manager.c: Enable resetting of the thread scheduling policy to SCHED_OTHER when the parent thread has a different one. 1998-02-01 13:51 Ulrich Drepper <drepper@cygnus.com> * sysdeps/unix/sysv/linux/bits/posix_opt.h: Define _POSIX_ASYNCHRONOUS_IO. * sysdeps/pthread/pthread.h: Define bits for Unix98 variants of mutexes. * mutex.c: Implement new mutex types. * internals.h: Include <signal.h>. * libpthread.map: Add __erno_location and __h_errno_location. * errno.c: Return pointer to variable actually in use. This might not be the one in the thread structure. * internals.h (struct _pthread_descr_struct): Add new fields p_errnop and p_h_errnop. * manager.c (__pthread_manager): Set p_errnop and p_h_errnop member of manager thread structure. (pthread_handle_create): Set p_errnop and p_h_errnop members for new thread. * pthread.c: Adapt initializer for thread structures. (__pthread_initial_thread): Set p_errnop and p_h_errnop member. (__pthread_reset_main_thread): Reset p_errnop and p_h_errnop of current thread to global variables. 1998-01-31 17:27 Ulrich Drepper <drepper@cygnus.com> * rwlock.c: New file. * Makefile (libpthread-routines): Add rwlock. * sysdeps/pthread/pthread.h: Define data structures and declare functions. * libpthread.map: Add new functions. 1997-12-18 13:50 Philip Blundell <pb@nexus.co.uk> * sysdeps/arm/pt-machine.h: New file; add ARM support. * sysdeps/arm/Implies: likewise. * README: Document it. 1997-12-13 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * signals.c: Remove unneeded initializer for sigwaited, saving a 1997-04-11 01:18 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * semaphore.c (sem_init): Set sem_spinlock only if available. 1997-12-04 01:48 Ulrich Drepper <drepper@cygnus.com> * mutex.c: Implement PTHREAD_MUTEX_CHECKERROR. * sysdeps/pthread/pthread.h: Define PTHREAD_MUTEX_CHECKERROR. * Makefile: Update from LinuxThreads 0.7. * internals.h. Likewise. * manager.c: Likewise. * mutex.c: Likewise. * pthread.c: Likewise. * signals.c: Likewise. * specific.c: Likewise. * Examples/ex3.c: Likewise. 1997-11-20 18:13 Ulrich Drepper <drepper@cygnus.com> * pthread.c (__pthread_reset_main_thread): Close pipe only if still open. 1997-10-29 05:38 Ulrich Drepper <drepper@cygnus.com> * wrapsyscall.c: Add socket functions which are also cancelation points. 1997-10-19 21:40 Wolfram Gloger <wg@wolfram.dent.med.uni-muenchen.de> * specific.c (__libc_internal_tsd_set, __libc_internal_tsd_get): New functions for fast thread specific data within libc. * internals.h: Add new array p_libc_specific to struct _pthread_descr_struct. * sysdeps/pthread/bits/libc-lock.h: Declare new functions. 1997-10-13 05:39 Ulrich Drepper <drepper@cygnus.com> * semaphore.h: Add __BEGIN_DECLS/__END_DECLS. Reported by Ralf Corsepius <corsepiu@faw.uni-ulm.de>. 1997-08-29 03:05 Ulrich Drepper <drepper@cygnus.com> * internals.h (struct _pthread_descr_struct): Add definitions for two-level specific key handling. * manager.c (pthread_handle_create): Initialize specific memory array. * specific.c: Implement two-level key handling. * weaks.c: Don't provide dummy key handling. * sysdeps/pthread/bits/libc-lock.h: Typedef __libc_lock_t (no #define). Add definition of __libc_key_t. * sysdeps/unix/sysv/linux/bits/local_lim.h: Define PTHREAD_KEYS_MAX as 1024. Add definition of _POSIX_THREAD_DESTRUCTOR_ITERATIONS and PTHREAD_DESTRUCTOR_ITERATIONS. * manager.c (pthread_handle_create): Compare mmap result with MAP_FAILED. * ptfork.c: Rename to __pthread_atfork and make old name a weak alias. * sysdeps/pthread/bits/pthread.h: Add prototype for __pthread_atfork. 1997-08-22 19:04 Richard Henderson <rth@cygnus.com> sysdeps/sparc -> sysdeps/sparc/sparc32 sysdeps/sparc64 -> sysdeps/sparc/sparc64 * internals.h: Change definition of THREAD_SELF to be an expression, not a statement that did a return. * sysdeps/alpha/pt-machine.h (THREAD_SELF): Update accordingly. * sysdeps/sparc/sparc32/pt-machine.h (THREAD_SELF, INIT_THREAD_SELF): Follow Solaris and use a "system reserved" register (%g6) to hold the thread descriptor. * sysdeps/sparc/sparc64/pt-machine.h: Likewise. 1997-08-03 00:09 Ulrich Drepper <drepper@cygnus.com> * mutex.c: Correct pthread_once. Patch by Xavier Leroy. * sysdeps/pthread/pthread.h: Add prototype for __pthread_once. * sysdeps/pthread/bits/pthread.h: Add macros for __libc_once. * semaphore.c: Include spinlock.h only when needed. * specific.c (__pthread_setsepcific, __pthread_getspecific): Reject keys for entries not in use. * weaks.c: Implement key handling functions for real. 1997-06-29 01:04 Richard Henderson <richard@gnu.ai.mit.edu> Initial sparc64-linux support: * linuxthreads/sysdeps/sparc64/Implies: New file. * linuxthreads/sysdeps/sparc64/pt-machine.h: Likewise. 1997-06-29 00:48 Ulrich Drepper <drepper@cygnus.com> * semaphore.c: Include spinlock.h at correct place. Patch by HJ Lu. 1997-06-13 10:06 Richard Henderson <rth@tamu.edu> The Great Bit File Move: * sysdeps/alpha/semaphorebits.h: -> .../bits/semaphore.h. * sysdeps/powerpc/semaphorebits.h: Likewise. * sysdeps/pthread/cmpxchg/semaphorebits.h: Likewise. * sysdeps/pthread/no-cmpxchg/semaphorebits.h: Likewise. * sysdeps/pthread/libc-lock.h: -> bits/ * sysdeps/pthread/stdio-lock.h: Likewise. * sysdeps/unix/sysv/linux/local_lim.h: Likewise. * sysdeps/unix/sysv/linux/posix_opt.h: Likewise. * semaphore.h: Likewise. * sysdeps/pthread/pthread.h: Likewise. * lockfile.c: <foo.h> -> <bits/foo.h>. * semaphore.h: Likewise. * Makefile: (headers): foo.h -> bits/foo.h. * sysdeps/pthread/Makefile: Likewise. 1997-04-11 01:18 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * semaphore.c (sem_init): Set sem_spinlock only if available. * sysdeps/m68k/pt-machine.h (testandset, __compare_and_swap): Fix asm constraints. 1997-04-09 03:00 Ulrich Drepper <drepper@cygnus.com> Update from LinuxThreads 0.6. * attr.c (pthread_attr_getdetachstate): Use __sched_get_priority_max and __sched_get_priority_min instead of names without `__'. * manager.c: Rewrite large parts to implement opaque pthread_t. * cancel.c: Adapt for opaque pthread_t type. * condvar.c: Likewise. * errno.c: Likewise. * join.c: Likewise. * mutex.c: Likewise. * pthread.c: Likewise. * signals.c: Likewise. * specific.c: Likewise. * restart.h: Likewise. * queue.h: Likewise. * Examples/ex3.c: Likewise. * Examples/ex4.c: Likewise. * sysdeps/pthread/pthread.h: Likewise. * pthread.c: Accumulate time for all threads in thread manager. * semaphore.c: Implement fallback implementation for architectures sometimes missing compare-exchange operations. * cancel.c (pthread_cancel): Validate handle argument. * join.c (pthread_join): Likewise. (pthread_detach): Likewise. * signals.c (pthread_kill): Likewise. * spinlock.h (acquire): Use __sched_yield not sched_yield. * queue.h (enqueue): Enqueue thread according to priority. * internals.c (struct pthread_start_args): New struct for passing args to cloning function. (struct _pthread): Rename to _pthread_descr_struct and adapt for opaque pthread_t. * Examples/Makefile (clean): Pass -f option to rm. * sysdeps/i386/pt-machine.h: Add check for compare-exchange instruction and define TEST_FOR_COMPARE_AND_SWAP. * sysdeps/i386/i486/pt-machine.h: Removed. * sysdeps/unix/sysv/linux/local_lim.h (PTHREAD_THREADS_MAX): Increase to 1024. 1997-04-04 16:38 Ulrich Drepper <drepper@cygnus.com> * restart.h (suspend): Clear p_signal before suspending. (suspend_with_cancellation): Likewise. Patch by Xavier Leroy <Xavier.Leroy@inria.fr>. * weaks.c: Make __pthread_key_create return 1. * sysdeps/pthread/libc-lock.h: Define __libc_key_create, __libc_getspecific, __libc_setspecific, and __libc_key_t. * sysdeps/pthread/stdio-lock.h: Don't care for implementation not using libio. 1997-03-19 15:13 Miguel de Icaza <miguel@nuclecu.unam.mx> * sysdeps/sparc/pt-machine (RELEASE): Fix. 1997-03-01 07:55 Geoff Keating <geoffk@ozemail.com.au> * sysdeps/powerpc/Implies: Added. * sysdeps/powerpc/pt-machine.h: Added. * sysdeps/powerpc/semaphorebits.h: Added. 1997-01-22 01:22 Ulrich Drepper <drepper@cygnus.com> * linuxtheads/pthread.c (__pthread_initial_thread): Correct initializer. (__pthread_manager_thread): Likewise. Reported by Andreas Jaeger. 1997-01-18 22:15 Richard Henderson <rth@tamu.edu> Since sigset_t no longer fits in a register, we can't pass in the thread's initial mask so easily. Take this opportunity to simplify the clone implementation by only accepting a single void* argument. * linuxthreads/manager.c (__pthread_manager): Put thread vitals in the thread struct instead of as arguments through clone. (pthread_start_thread): Look for them there. * linuxthreads/internals.h (struct _pthread): Add p_initial_fn, p_initial_fn_arg, p_initial_mask. Fix __pthread_manager proto. * linuxthreads/pthread.c (pthread_initialize_manager): Revise clone invocation.
Diffstat (limited to 'linuxthreads/man/pthread_mutex_init.man')
-rw-r--r-- | linuxthreads/man/pthread_mutex_init.man | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/linuxthreads/man/pthread_mutex_init.man b/linuxthreads/man/pthread_mutex_init.man new file mode 100644 index 0000000000..bda4ec6c4d --- /dev/null +++ b/linuxthreads/man/pthread_mutex_init.man @@ -0,0 +1,213 @@ +.TH PTHREAD_MUTEX 3 LinuxThreads + +.XREF pthread_mutex_lock +.XREF pthread_mutex_unlock +.XREF pthread_mutex_trylock +.XREF pthread_mutex_destroy + +.SH NAME +pthread_mutex_init, pthread_mutex_lock, pthread_mutex_trylock, pthread_mutex_unlock, pthread_mutex_destroy \- operations on mutexes + +.SH SYNOPSIS +#include <pthread.h> + +pthread_mutex_t fastmutex = PTHREAD_MUTEX_INITIALIZER; + +pthread_mutex_t recmutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP; + +pthread_mutex_t errchkmutex = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP; + +int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexattr); + +int pthread_mutex_lock(pthread_mutex_t *mutex)); + +int pthread_mutex_trylock(pthread_mutex_t *mutex); + +int pthread_mutex_unlock(pthread_mutex_t *mutex); + +int pthread_mutex_destroy(pthread_mutex_t *mutex); + +.SH DESCRIPTION +A mutex is a MUTual EXclusion device, and is useful for protecting +shared data structures from concurrent modifications, and implementing +critical sections and monitors. + +A mutex has two possible states: unlocked (not owned by any thread), +and locked (owned by one thread). A mutex can never be owned by two +different threads simultaneously. A thread attempting to lock a mutex +that is already locked by another thread is suspended until the owning +thread unlocks the mutex first. + +!pthread_mutex_init! initializes the mutex object pointed to by +|mutex| according to the mutex attributes specified in |mutexattr|. +If |mutexattr| is !NULL!, default attributes are used instead. + +The LinuxThreads implementation supports only one mutex attributes, +the |mutex kind|, which is either ``fast'', ``recursive'', or +``error checking''. The kind of a mutex determines whether +it can be locked again by a thread that already owns it. +The default kind is ``fast''. See !pthread_mutexattr_init!(3) for more +information on mutex attributes. + +Variables of type !pthread_mutex_t! can also be initialized +statically, using the constants !PTHREAD_MUTEX_INITIALIZER! (for fast +mutexes), !PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP! (for recursive +mutexes), and !PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP! (for error checking +mutexes). + +!pthread_mutex_lock! locks the given mutex. If the mutex is currently +unlocked, it becomes locked and owned by the calling thread, and +!pthread_mutex_lock! returns immediately. If the mutex is already +locked by another thread, !pthread_mutex_lock! suspends the calling +thread until the mutex is unlocked. + +If the mutex is already locked by the calling thread, the behavior of +!pthread_mutex_lock! depends on the kind of the mutex. If the mutex is +of the ``fast'' kind, the calling thread is suspended until the mutex +is unlocked, thus effectively causing the calling thread to +deadlock. If the mutex is of the ``error checking'' kind, +!pthread_mutex_lock! returns immediately with the error code !EDEADLK!. +If the mutex is of the ``recursive'' kind, !pthread_mutex_lock! +succeeds and returns immediately, recording the number of times the +calling thread has locked the mutex. An equal number of +!pthread_mutex_unlock! operations must be performed before the mutex +returns to the unlocked state. + +!pthread_mutex_trylock! behaves identically to !pthread_mutex_lock!, +except that it does not block the calling thread if the mutex is +already locked by another thread (or by the calling thread in the case +of a ``fast'' mutex). Instead, !pthread_mutex_trylock! returns +immediately with the error code !EBUSY!. + +!pthread_mutex_unlock! unlocks the given mutex. The mutex is assumed +to be locked and owned by the calling thread on entrance to +!pthread_mutex_unlock!. If the mutex is of the ``fast'' kind, +!pthread_mutex_unlock! always returns it to the unlocked state. If it +is of the ``recursive'' kind, it decrements the locking count of the +mutex (number of !pthread_mutex_lock! operations performed on it by +the calling thread), and only when this count reaches zero is the +mutex actually unlocked. + +On ``error checking'' mutexes, !pthread_mutex_unlock! actually checks +at run-time that the mutex is locked on entrance, and that it was +locked by the same thread that is now calling !pthread_mutex_unlock!. +If these conditions are not met, an error code is returned and the +mutex remains unchanged. ``Fast'' and ``recursive'' mutexes perform +no such checks, thus allowing a locked mutex to be unlocked by a +thread other than its owner. This is non-portable behavior and must +not be relied upon. + +!pthread_mutex_destroy! destroys a mutex object, freeing the resources +it might hold. The mutex must be unlocked on entrance. In the +LinuxThreads implementation, no resources are associated with mutex +objects, thus !pthread_mutex_destroy! actually does nothing except +checking that the mutex is unlocked. + +.SH CANCELLATION + +None of the mutex functions is a cancellation point, not even +!pthread_mutex_lock!, in spite of the fact that it can suspend a +thread for arbitrary durations. This way, the status of mutexes at +cancellation points is predictable, allowing cancellation handlers to +unlock precisely those mutexes that need to be unlocked before the +thread stops executing. Consequently, threads using deferred +cancellation should never hold a mutex for extended periods of time. + +.SH "ASYNC-SIGNAL SAFETY" + +The mutex functions are not async-signal safe. What this means is that +they should not be called from a signal handler. In particular, +calling !pthread_mutex_lock! or !pthread_mutex_unlock! from a signal +handler may deadlock the calling thread. + +.SH "RETURN VALUE" + +!pthread_mutex_init! always returns 0. The other mutex functions +return 0 on success and a non-zero error code on error. + +.SH ERRORS + +The !pthread_mutex_lock! function returns the following error code +on error: +.RS +.TP +!EINVAL! +the mutex has not been properly initialized. + +.TP +!EDEADLK! +the mutex is already locked by the calling thread +(``error checking'' mutexes only). +.RE + +The !pthread_mutex_trylock! function returns the following error codes +on error: +.RS +.TP +!EBUSY! +the mutex could not be acquired because it was currently locked. + +.TP +!EINVAL! +the mutex has not been properly initialized. +.RE + +The !pthread_mutex_unlock! function returns the following error code +on error: +.RS +.TP +!EINVAL! +the mutex has not been properly initialized. + +.TP +!EPERM! +the calling thread does not own the mutex (``error checking'' mutexes only). +.RE + +The !pthread_mutex_destroy! function returns the following error code +on error: +.RS +.TP +!EBUSY! +the mutex is currently locked. +.RE + +.SH AUTHOR +Xavier Leroy <Xavier.Leroy@inria.fr> + +.SH "SEE ALSO" +!pthread_mutexattr_init!(3), +!pthread_mutexattr_setkind_np!(3), +!pthread_cancel!(3). + +.SH EXAMPLE + +A shared global variable |x| can be protected by a mutex as follows: + +.RS +.ft 3 +.nf +.sp +int x; +pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER; +.ft +.LP +.RE +.fi + +All accesses and modifications to |x| should be bracketed by calls to +!pthread_mutex_lock! and !pthread_mutex_unlock! as follows: + +.RS +.ft 3 +.nf +.sp +pthread_mutex_lock(&mut); +/* operate on x */ +pthread_mutex_unlock(&mut); +.ft +.LP +.RE +.fi + + |