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Diffstat (limited to 'linuxthreads/oldsemaphore.c')
| -rw-r--r-- | linuxthreads/oldsemaphore.c | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/linuxthreads/oldsemaphore.c b/linuxthreads/oldsemaphore.c deleted file mode 100644 index d35683b98b..0000000000 --- a/linuxthreads/oldsemaphore.c +++ /dev/null @@ -1,241 +0,0 @@ -/* - * This file contains the old semaphore code that we need to - * preserve for glibc-2.0 backwards compatibility. Port to glibc 2.1 - * done by Cristian Gafton. - */ - -/* Linuxthreads - a simple clone()-based implementation of Posix */ -/* threads for Linux. */ -/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */ -/* */ -/* This program 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. */ -/* */ -/* This program 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. */ - -/* Semaphores a la POSIX 1003.1b */ -#include <shlib-compat.h> -#if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1) - -#include <errno.h> -#include "pthread.h" -#include "internals.h" -#include "spinlock.h" -#include "restart.h" -#include "queue.h" - -typedef struct { - long int sem_status; - int sem_spinlock; -} old_sem_t; - -extern int __old_sem_init (old_sem_t *__sem, int __pshared, unsigned int __value); -extern int __old_sem_wait (old_sem_t *__sem); -extern int __old_sem_trywait (old_sem_t *__sem); -extern int __old_sem_post (old_sem_t *__sem); -extern int __old_sem_getvalue (old_sem_t *__sem, int *__sval); -extern int __old_sem_destroy (old_sem_t *__sem); - -static inline int sem_compare_and_swap(old_sem_t *sem, long oldval, long newval) -{ - return compare_and_swap(&sem->sem_status, oldval, newval, &sem->sem_spinlock); -} - -/* The state of a semaphore is represented by a long int encoding - either the semaphore count if >= 0 and no thread is waiting on it, - or the head of the list of threads waiting for the semaphore. - To distinguish the two cases, we encode the semaphore count N - as 2N+1, so that it has the lowest bit set. - - A sequence of sem_wait operations on a semaphore initialized to N - result in the following successive states: - 2N+1, 2N-1, ..., 3, 1, &first_waiting_thread, &second_waiting_thread, ... -*/ - -static void sem_restart_list(pthread_descr waiting); - -int __old_sem_init(old_sem_t *sem, int pshared, unsigned int value) -{ - if (value > SEM_VALUE_MAX) { - errno = EINVAL; - return -1; - } - if (pshared) { - errno = ENOSYS; - return -1; - } - sem->sem_spinlock = __LT_SPINLOCK_INIT; - sem->sem_status = ((long)value << 1) + 1; - return 0; -} - -/* Function called by pthread_cancel to remove the thread from - waiting inside __old_sem_wait. Here we simply unconditionally - indicate that the thread is to be woken, by returning 1. */ - -static int old_sem_extricate_func(void *obj, pthread_descr th) -{ - return 1; -} - -int __old_sem_wait(old_sem_t * sem) -{ - long oldstatus, newstatus; - volatile pthread_descr self = thread_self(); - pthread_descr * th; - pthread_extricate_if extr; - - /* Set up extrication interface */ - extr.pu_object = 0; - extr.pu_extricate_func = old_sem_extricate_func; - - while (1) { - /* Register extrication interface */ - __pthread_set_own_extricate_if(self, &extr); - do { - oldstatus = sem->sem_status; - if ((oldstatus & 1) && (oldstatus != 1)) - newstatus = oldstatus - 2; - else { - newstatus = (long) self; - self->p_nextwaiting = (pthread_descr) oldstatus; - } - } - while (! sem_compare_and_swap(sem, oldstatus, newstatus)); - if (newstatus & 1) { - /* We got the semaphore. */ - __pthread_set_own_extricate_if(self, 0); - self->p_nextwaiting = NULL; - return 0; - } - /* Wait for sem_post or cancellation */ - suspend(self); - __pthread_set_own_extricate_if(self, 0); - - /* This is a cancellation point */ - if (self->p_canceled && self->p_cancelstate == PTHREAD_CANCEL_ENABLE) { - /* Remove ourselves from the waiting list if we're still on it */ - /* First check if we're at the head of the list. */ - do { - oldstatus = sem->sem_status; - if (oldstatus != (long) self) break; - newstatus = (long) self->p_nextwaiting; - } - while (! sem_compare_and_swap(sem, oldstatus, newstatus)); - /* Now, check if we're somewhere in the list. - There's a race condition with sem_post here, but it does not matter: - the net result is that at the time pthread_exit is called, - self is no longer reachable from sem->sem_status. */ - if (oldstatus != (long) self && (oldstatus & 1) == 0) { - for (th = &(((pthread_descr) oldstatus)->p_nextwaiting); - *th != NULL && *th != (pthread_descr) 1; - th = &((*th)->p_nextwaiting)) { - if (*th == self) { - *th = self->p_nextwaiting; - break; - } - } - } - __pthread_do_exit(PTHREAD_CANCELED, CURRENT_STACK_FRAME); - } - } -} - -int __old_sem_trywait(old_sem_t * sem) -{ - long oldstatus, newstatus; - - do { - oldstatus = sem->sem_status; - if ((oldstatus & 1) == 0 || (oldstatus == 1)) { - errno = EAGAIN; - return -1; - } - newstatus = oldstatus - 2; - } - while (! sem_compare_and_swap(sem, oldstatus, newstatus)); - return 0; -} - -int __old_sem_post(old_sem_t * sem) -{ - long oldstatus, newstatus; - - do { - oldstatus = sem->sem_status; - if ((oldstatus & 1) == 0) - newstatus = 3; - else { - if (oldstatus >= SEM_VALUE_MAX) { - /* Overflow */ - errno = ERANGE; - return -1; - } - newstatus = oldstatus + 2; - } - } - while (! sem_compare_and_swap(sem, oldstatus, newstatus)); - if ((oldstatus & 1) == 0) - sem_restart_list((pthread_descr) oldstatus); - return 0; -} - -int __old_sem_getvalue(old_sem_t * sem, int * sval) -{ - long status = sem->sem_status; - if (status & 1) - *sval = (int)((unsigned long) status >> 1); - else - *sval = 0; - return 0; -} - -int __old_sem_destroy(old_sem_t * sem) -{ - if ((sem->sem_status & 1) == 0) { - errno = EBUSY; - return -1; - } - return 0; -} - -/* Auxiliary function for restarting all threads on a waiting list, - in priority order. */ - -static void sem_restart_list(pthread_descr waiting) -{ - pthread_descr th, towake, *p; - - /* Sort list of waiting threads by decreasing priority (insertion sort) */ - towake = NULL; - while (waiting != (pthread_descr) 1) { - th = waiting; - waiting = waiting->p_nextwaiting; - p = &towake; - while (*p != NULL && th->p_priority < (*p)->p_priority) - p = &((*p)->p_nextwaiting); - th->p_nextwaiting = *p; - *p = th; - } - /* Wake up threads in priority order */ - while (towake != NULL) { - th = towake; - towake = towake->p_nextwaiting; - th->p_nextwaiting = NULL; - restart(th); - } -} - -compat_symbol (libpthread, __old_sem_init, sem_init, GLIBC_2_0); -compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0); -compat_symbol (libpthread, __old_sem_trywait, sem_trywait, GLIBC_2_0); -compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0); -compat_symbol (libpthread, __old_sem_getvalue, sem_getvalue, GLIBC_2_0); -compat_symbol (libpthread, __old_sem_destroy, sem_destroy, GLIBC_2_0); - -#endif |