glibc/linuxthreads/rwlock.c
Ulrich Drepper 5afdca0087 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.
1998-03-11 12:42:25 +00:00

277 lines
5.8 KiB
C

/* Read-write lock implementation.
Copyright (C) 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Xavier Leroy <Xavier.Leroy@inria.fr>
and Ulrich Drepper <drepper@cygnus.com>, 1998.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <errno.h>
#include <pthread.h>
#include "internals.h"
#include "queue.h"
#include "restart.h"
#include "spinlock.h"
int
pthread_rwlock_init (pthread_rwlock_t *rwlock,
const pthread_rwlockattr_t *attr)
{
rwlock->rw_spinlock = 0;
rwlock->rw_readers = 0;
rwlock->rw_writer = NULL;
queue_init(&rwlock->rw_read_waiting);
queue_init(&rwlock->rw_write_waiting);
if (attr == NULL)
{
rwlock->rw_kind = PTHREAD_RWLOCK_DEFAULT_NP;
rwlock->rw_pshared = PTHREAD_PROCESS_PRIVATE;
}
else
{
rwlock->rw_kind = attr->lockkind;
rwlock->rw_pshared = attr->pshared;
}
return 0;
}
int
pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
{
int readers;
_pthread_descr writer;
acquire (&rwlock->rw_spinlock);
readers = rwlock->rw_readers;
writer = rwlock->rw_writer;
release (&rwlock->rw_spinlock);
if (readers > 0 || writer != NULL)
return EBUSY;
return 0;
}
int
pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
{
pthread_descr self;
while (1)
{
acquire (&rwlock->rw_spinlock);
if (rwlock->rw_writer == NULL
|| (rwlock->rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP
&& rwlock->rw_readers != 0))
/* We can add a reader lock. */
break;
/* Suspend ourselves, then try again */
self = thread_self ();
enqueue (&rwlock->rw_read_waiting, self);
release (&rwlock->rw_spinlock);
suspend (self); /* This is not a cancellation point */
}
++rwlock->rw_readers;
release (&rwlock->rw_spinlock);
return 0;
}
int
pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
{
int result = EBUSY;
acquire (&rwlock->rw_spinlock);
if (rwlock->rw_writer == NULL
|| (rwlock->rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP
&& rwlock->rw_readers != 0))
{
++rwlock->rw_readers;
result = 0;
}
release (&rwlock->rw_spinlock);
return result;
}
int
pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
{
pthread_descr self = thread_self ();
while(1)
{
acquire (&rwlock->rw_spinlock);
if (rwlock->rw_readers == 0 && rwlock->rw_writer == NULL)
{
rwlock->rw_writer = self;
release (&rwlock->rw_spinlock);
return 0;
}
/* Suspend ourselves, then try again */
enqueue (&rwlock->rw_write_waiting, self);
release (&rwlock->rw_spinlock);
suspend (self); /* This is not a cancellation point */
}
}
int
pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
{
int result = EBUSY;
acquire (&rwlock->rw_spinlock);
if (rwlock->rw_readers == 0 && rwlock->rw_writer == NULL)
{
rwlock->rw_writer = thread_self ();
result = 0;
}
release (&rwlock->rw_spinlock);
return result;
}
int
pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
{
struct _pthread_queue torestart;
pthread_descr th;
acquire (&rwlock->rw_spinlock);
if (rwlock->rw_writer != NULL)
{
/* Unlocking a write lock. */
if (rwlock->rw_writer != thread_self ())
{
release (&rwlock->rw_spinlock);
return EPERM;
}
rwlock->rw_writer = NULL;
if (rwlock->rw_kind == PTHREAD_RWLOCK_PREFER_READER_NP
|| (th = dequeue (&rwlock->rw_write_waiting)) == NULL)
{
/* Restart all waiting readers. */
torestart = rwlock->rw_read_waiting;
queue_init (&rwlock->rw_read_waiting);
release (&rwlock->rw_spinlock);
while ((th = dequeue (&torestart)) != NULL)
restart (th);
}
else
{
/* Restart one waiting writer. */
release (&rwlock->rw_spinlock);
restart (th);
}
}
else
{
/* Unlocking a read lock. */
if (rwlock->rw_readers == 0)
{
release (&rwlock->rw_spinlock);
return EPERM;
}
--rwlock->rw_readers;
if (rwlock->rw_readers == 0)
/* Restart one waiting writer, if any. */
th = dequeue (&rwlock->rw_write_waiting);
else
th = NULL;
release (&rwlock->rw_spinlock);
if (th != NULL)
restart (th);
}
return 0;
}
int
pthread_rwlockattr_init (pthread_rwlockattr_t *attr)
{
attr->lockkind = 0;
attr->pshared = 0;
return 0;
}
int
pthread_rwlockattr_destroy (pthread_rwlockattr_t *attr)
{
return 0;
}
int
pthread_rwlockattr_getpshared (const pthread_rwlockattr_t *attr, int *pshared)
{
*pshared = attr->pshared;
return 0;
}
int
pthread_rwlockattr_setpshared (pthread_rwlockattr_t *attr, int pshared)
{
if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
return EINVAL;
attr->pshared = pshared;
return 0;
}
int
pthread_rwlockattr_getkind_np (const pthread_rwlockattr_t *attr, int *pref)
{
*pref = attr->lockkind;
return 0;
}
int
pthread_rwlockattr_setkind_np (pthread_rwlockattr_t *attr, int pref)
{
if (pref != PTHREAD_RWLOCK_PREFER_READER_NP
&& pref != PTHREAD_RWLOCK_PREFER_WRITER_NP
&& pref != PTHREAD_RWLOCK_DEFAULT_NP)
return EINVAL;
attr->lockkind = pref;
return 0;
}