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/*
* David Leonard <d@openbsd.org>, 1999. Public domain.
* $FreeBSD$
*/
#include <sys/errno.h>
#include <pthread.h>
#include <stdlib.h>
#include "thr_private.h"
/*
* Static prototypes
*/
static void testcancel(void);
__weak_reference(_pthread_cancel, pthread_cancel);
__weak_reference(_pthread_setcancelstate, pthread_setcancelstate);
__weak_reference(_pthread_setcanceltype, pthread_setcanceltype);
__weak_reference(_pthread_testcancel, pthread_testcancel);
int
_pthread_cancel(pthread_t pthread)
{
int ret;
pthread_t joined;
/*
* When canceling a thread that has joined another thread, this
* routine breaks the normal lock order of locking first the
* joined and then the joiner. Therefore, it is necessary that
* if it can't obtain the second lock, that it release the first
* one and restart from the top.
*/
retry:
if ((ret = _find_thread(pthread)) != 0)
/* The thread is not on the list of active threads */
goto out;
_thread_critical_enter(pthread);
if (pthread->state == PS_DEAD || pthread->state == PS_DEADLOCK
|| (pthread->flags & PTHREAD_EXITING) != 0) {
/*
* The thread is in the process of (or has already) exited
* or is deadlocked.
*/
_thread_critical_exit(pthread);
ret = 0;
goto out;
}
/*
* The thread is on the active thread list and is not in the process
* of exiting.
*/
if (((pthread->cancelflags & PTHREAD_CANCEL_DISABLE) != 0) ||
(((pthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) == 0) &&
((pthread->cancelflags & PTHREAD_AT_CANCEL_POINT) == 0)))
/* Just mark it for cancellation: */
pthread->cancelflags |= PTHREAD_CANCELLING;
else {
/*
* Check if we need to kick it back into the
* run queue:
*/
switch (pthread->state) {
case PS_RUNNING:
/* No need to resume: */
pthread->cancelflags |= PTHREAD_CANCELLING;
break;
case PS_SLEEP_WAIT:
case PS_WAIT_WAIT:
pthread->cancelflags |= PTHREAD_CANCELLING;
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
break;
case PS_JOIN:
/*
* Disconnect the thread from the joinee:
*/
if ((joined = pthread->join_status.thread) != NULL) {
UMTX_TRYLOCK(&joined->lock, ret);
if (ret == EBUSY) {
_thread_critical_exit(pthread);
goto retry;
}
pthread->join_status.thread->joiner = NULL;
UMTX_UNLOCK(&joined->lock);
joined = pthread->join_status.thread = NULL;
}
pthread->cancelflags |= PTHREAD_CANCELLING;
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
break;
case PS_BARRIER_WAIT:
case PS_MUTEX_WAIT:
case PS_COND_WAIT:
/*
* Threads in these states may be in queues.
* In order to preserve queue integrity, the
* cancelled thread must remove itself from the
* queue. When the thread resumes, it will
* remove itself from the queue and call the
* cancellation routine.
*/
pthread->cancelflags |= PTHREAD_CANCELLING;
PTHREAD_NEW_STATE(pthread, PS_RUNNING);
break;
case PS_DEAD:
case PS_DEADLOCK:
case PS_STATE_MAX:
/* Ignore - only here to silence -Wall: */
break;
}
}
/* Unprotect the scheduling queues: */
_thread_critical_exit(pthread);
ret = 0;
out:
return (ret);
}
int
_pthread_setcancelstate(int state, int *oldstate)
{
int ostate, ret;
ret = 0;
_thread_critical_enter(curthread);
ostate = curthread->cancelflags & PTHREAD_CANCEL_DISABLE;
switch (state) {
case PTHREAD_CANCEL_ENABLE:
if (oldstate != NULL)
*oldstate = ostate;
curthread->cancelflags &= ~PTHREAD_CANCEL_DISABLE;
if ((curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS) == 0)
break;
testcancel();
break;
case PTHREAD_CANCEL_DISABLE:
if (oldstate != NULL)
*oldstate = ostate;
curthread->cancelflags |= PTHREAD_CANCEL_DISABLE;
break;
default:
ret = EINVAL;
}
_thread_critical_exit(curthread);
return (ret);
}
int
_pthread_setcanceltype(int type, int *oldtype)
{
int otype;
_thread_critical_enter(curthread);
otype = curthread->cancelflags & PTHREAD_CANCEL_ASYNCHRONOUS;
switch (type) {
case PTHREAD_CANCEL_ASYNCHRONOUS:
if (oldtype != NULL)
*oldtype = otype;
curthread->cancelflags |= PTHREAD_CANCEL_ASYNCHRONOUS;
testcancel();
break;
case PTHREAD_CANCEL_DEFERRED:
if (oldtype != NULL)
*oldtype = otype;
curthread->cancelflags &= ~PTHREAD_CANCEL_ASYNCHRONOUS;
break;
default:
return (EINVAL);
}
_thread_critical_exit(curthread);
return (0);
}
void
_pthread_testcancel(void)
{
_thread_critical_enter(curthread);
testcancel();
_thread_critical_exit(curthread);
}
static void
testcancel()
{
/*
* This pthread should already be locked by the caller.
*/
if (((curthread->cancelflags & PTHREAD_CANCEL_DISABLE) == 0) &&
((curthread->cancelflags & PTHREAD_CANCELLING) != 0) &&
((curthread->flags & PTHREAD_EXITING) == 0)) {
/*
* It is possible for this thread to be swapped out
* while performing cancellation; do not allow it
* to be cancelled again.
*/
curthread->cancelflags &= ~PTHREAD_CANCELLING;
_thread_critical_exit(curthread);
_thread_exit_cleanup();
pthread_exit(PTHREAD_CANCELED);
PANIC("cancel");
}
}
void
_thread_enter_cancellation_point(void)
{
_thread_critical_enter(curthread);
testcancel();
curthread->cancelflags |= PTHREAD_AT_CANCEL_POINT;
_thread_critical_exit(curthread);
}
void
_thread_leave_cancellation_point(void)
{
_thread_critical_enter(curthread);
curthread->cancelflags &= ~PTHREAD_AT_CANCEL_POINT;
testcancel();
_thread_critical_exit(curthread);
}
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