cancel.c revision 7257d1b4d25bfac0c802847390e98a464fd787ac
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
#include "lint.h"
#include "thr_uberdata.h"
/*
* pthread_cancel: tries to cancel the targeted thread.
* If the target thread has already exited no action is taken.
* Else send SIGCANCEL to request the other thread to cancel itself.
*/
int
{
int error = 0;
return (ESRCH);
if (ulwp->ul_cancel_pending) {
/*
* Don't send SIGCANCEL more than once.
*/
/*
* Unlock self before cancelling.
*/
if (self->ul_sigdefer == 0)
do_sigcancel();
else {
}
} else if (ulwp->ul_cancel_disabled) {
/*
* Don't send SIGCANCEL if cancellation is disabled;
* just set the thread's ulwp->ul_cancel_pending flag.
* This avoids a potential EINTR for the target thread.
* We don't call set_cancel_pending_flag() here because
* we cannot modify another thread's schedctl data.
*/
} else {
/*
* Request the other thread to cancel itself.
*/
}
return (error);
}
/*
* pthread_setcancelstate: sets the state ENABLED or DISABLED.
* If the state is already ENABLED or is being set to ENABLED,
* the type of cancellation is ASYNCHRONOUS, and a cancel request
* is pending, then the thread is cancelled right here.
* Otherwise, pthread_setcancelstate() is not a cancellation point.
*/
int
{
int was_disabled;
/*
* Grab ulwp_lock(self) to protect the setting of ul_cancel_disabled
* since it is tested under this lock by pthread_cancel(), above.
* This has the side-effect of calling enter_critical() and this
* defers SIGCANCEL until ulwp_unlock(self) when exit_critical()
* is called. (self->ul_cancel_pending is set in the SIGCANCEL
* handler and we must be async-signal safe here.)
*/
switch (state) {
case PTHREAD_CANCEL_ENABLE:
self->ul_cancel_disabled = 0;
break;
case PTHREAD_CANCEL_DISABLE:
break;
default:
return (EINVAL);
}
/*
* If this thread has been requested to be canceled and
* is in async mode and is or was enabled, then exit.
*/
}
if (was_disabled)
else
}
return (0);
}
/*
* pthread_setcanceltype: sets the type DEFERRED or ASYNCHRONOUS
* If the type is being set as ASYNC, then it becomes
* a cancellation point if there is a cancellation pending.
*/
int
{
int was_async;
/*
* Call enter_critical() to defer SIGCANCEL until exit_critical().
* We do this because curthread->ul_cancel_pending is set in the
* SIGCANCEL handler and we must be async-signal safe here.
*/
switch (type) {
break;
case PTHREAD_CANCEL_DEFERRED:
self->ul_cancel_async = 0;
break;
default:
return (EINVAL);
}
/*
* If this thread has been requested to be canceled and
* is in enabled mode and is or was in async mode, exit.
*/
}
if (was_async)
else
}
return (0);
}
/*
* pthread_testcancel: tests for any cancellation pending
* if the cancellation is enabled and is pending, act on
* it by calling thr_exit. thr_exit takes care of calling
* cleanup handlers.
*/
void
pthread_testcancel(void)
{
}
/*
* For deferred mode, this routine makes a thread cancelable.
* It is called from the functions which want to be cancellation
* points and are about to block, such as cond_wait().
*/
void
{
if (!self->ul_cancel_disabled) {
self->ul_cancelable++;
if (self->ul_cancel_pending)
}
}
/*
* This routine turns cancelability off and possible calls pthread_exit().
* It is called from functions which are cancellation points, like cond_wait().
*/
void
{
if (!self->ul_cancel_disabled) {
if (self->ul_cancel_pending)
self->ul_cancelable--;
}
}
/*
* Same as _canceloff() but don't actually cancel the thread.
* This is used by cond_wait() and sema_wait() when they don't get EINTR.
*/
void
{
if (!self->ul_cancel_disabled) {
self->ul_cancelable--;
}
}
/*
* __pthread_cleanup_push: called by macro in pthread.h which defines
* POSIX.1c pthread_cleanup_push(). Macro in pthread.h allocates the
* cleanup struct and calls this routine to push the handler off the
* curthread's struct.
*/
void
__pthread_cleanup_push(void (*routine)(void *),
{
}
/*
* __pthread_cleanup_pop: called by macro in pthread.h which defines
* POSIX.1c pthread_cleanup_pop(). It calls this routine to pop the
* handler off the curthread's struct and execute it if necessary.
*/
/* ARGSUSED1 */
void
{
if (ex)
}
/*
* Called when either self->ul_cancel_disabled or self->ul_cancel_pending
* is modified. Setting SC_CANCEL_FLG informs the kernel that we have
* a pending cancellation and we do not have cancellation disabled.
* In this situation, we will not go to sleep on any system call but
* will instead return EINTR immediately on any attempt to sleep,
* with SC_EINTR_FLG set in sc_flgs. Clearing SC_CANCEL_FLG rescinds
* this condition, but SC_EINTR_FLG never goes away until the thread
* terminates (indicated by clear_flags != 0).
*/
void
{
volatile sc_shared_t *scp;
return;
if (clear_flags)
else
}
}
/*
* Called from the PROLOGUE macro in scalls.c to inform subsequent
* code that a cancellation point has been called and that the
* current thread should cancel itself as soon as all of its locks
* have been dropped (see safe_mutex_unlock()).
*/
void
{
volatile sc_shared_t *scp;
return;
}
/*
* Calling set_parking_flag(curthread, 1) informs the kernel that we are
* calling __lwp_park or ___lwp_cond_wait(). If we take a signal in
* the unprotected (from signals) interval before reaching the kernel,
* sigacthandler() will call set_parking_flag(curthread, 0) to inform
* the kernel to return immediately from these system calls, giving us
* a spurious wakeup but not a deadlock.
*/
void
{
volatile sc_shared_t *scp;
if (park) {
/*
* We are parking; allow the __lwp_park() call to
* block even if we have a pending cancellation.
*/
} else {
/*
* We are no longer parking; restore the
* pending cancellation flag if necessary.
*/
if (self->ul_cancel_pending &&
}
} else if (park == 0) { /* schedctl failed, do it the long way */
}
}
/*
* Test if the current thread is due to exit because of cancellation.
*/
int
cancel_active(void)
{
volatile sc_shared_t *scp;
int exit_soon;
/*
* If there is a pending cancellation and cancellation
* is not disabled (SC_CANCEL_FLG) and we received
* EINTR from a recent system call (SC_EINTR_FLG),
* then we will soon be exiting.
*/
(SC_CANCEL_FLG | SC_EINTR_FLG));
return (exit_soon);
}