1 /* ---------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2006
5 * Asynchronous exceptions
7 * --------------------------------------------------------------------------*/
9 #include "PosixSource.h"
12 #include "sm/Storage.h"
15 #include "RaiseAsync.h"
19 #include "sm/Sanity.h"
20 #include "Profiling.h"
22 #if defined(mingw32_HOST_OS)
23 #include "win32/IOManager.h"
26 static void raiseAsync (Capability *cap,
28 StgClosure *exception,
29 rtsBool stop_at_atomically,
30 StgUpdateFrame *stop_here);
32 static void removeFromQueues(Capability *cap, StgTSO *tso);
34 static void removeFromMVarBlockedQueue (StgTSO *tso);
36 static void blockedThrowTo (Capability *cap,
37 StgTSO *target, MessageThrowTo *msg);
39 static void throwToSendMsg (Capability *cap USED_IF_THREADS,
40 Capability *target_cap USED_IF_THREADS,
41 MessageThrowTo *msg USED_IF_THREADS);
43 /* -----------------------------------------------------------------------------
46 This version of throwTo is safe to use if and only if one of the
51 - all the other threads in the system are stopped (eg. during GC).
53 - we surely own the target TSO (eg. we just took it from the
54 run queue of the current capability, or we are running it).
56 It doesn't cater for blocking the source thread until the exception
58 -------------------------------------------------------------------------- */
61 throwToSingleThreaded(Capability *cap, StgTSO *tso, StgClosure *exception)
63 throwToSingleThreaded_(cap, tso, exception, rtsFalse);
67 throwToSingleThreaded_(Capability *cap, StgTSO *tso, StgClosure *exception,
68 rtsBool stop_at_atomically)
72 // Thread already dead?
73 if (tso->what_next == ThreadComplete || tso->what_next == ThreadKilled) {
77 // Remove it from any blocking queues
78 removeFromQueues(cap,tso);
80 raiseAsync(cap, tso, exception, stop_at_atomically, NULL);
84 suspendComputation(Capability *cap, StgTSO *tso, StgUpdateFrame *stop_here)
88 // Thread already dead?
89 if (tso->what_next == ThreadComplete || tso->what_next == ThreadKilled) {
93 // Remove it from any blocking queues
94 removeFromQueues(cap,tso);
96 raiseAsync(cap, tso, NULL, rtsFalse, stop_here);
99 /* -----------------------------------------------------------------------------
102 This function may be used to throw an exception from one thread to
103 another, during the course of normal execution. This is a tricky
104 task: the target thread might be running on another CPU, or it
105 may be blocked and could be woken up at any point by another CPU.
106 We have some delicate synchronisation to do.
108 The underlying scheme when multiple Capabilities are in use is
109 message passing: when the target of a throwTo is on another
110 Capability, we send a message (a MessageThrowTo closure) to that
113 If the throwTo needs to block because the target TSO is masking
114 exceptions (the TSO_BLOCKEX flag), then the message is placed on
115 the blocked_exceptions queue attached to the target TSO. When the
116 target TSO enters the unmasked state again, it must check the
117 queue. The blocked_exceptions queue is not locked; only the
118 Capability owning the TSO may modify it.
120 To make things simpler for throwTo, we always create the message
121 first before deciding what to do. The message may get sent, or it
122 may get attached to a TSO's blocked_exceptions queue, or the
123 exception may get thrown immediately and the message dropped,
124 depending on the current state of the target.
126 Currently we send a message if the target belongs to another
127 Capability, and it is
129 - NotBlocked, BlockedOnMsgThrowTo,
132 - or it is masking exceptions (TSO_BLOCKEX)
134 Currently, if the target is BlockedOnMVar, BlockedOnSTM, or
135 BlockedOnBlackHole then we acquire ownership of the TSO by locking
136 its parent container (e.g. the MVar) and then raise the exception.
137 We might change these cases to be more message-passing-like in the
142 NULL exception was raised, ok to continue
144 MessageThrowTo * exception was not raised; the source TSO
145 should now put itself in the state
146 BlockedOnMsgThrowTo, and when it is ready
147 it should unlock the mssage using
148 unlockClosure(msg, &stg_MSG_THROWTO_info);
149 If it decides not to raise the exception after
150 all, it can revoke it safely with
151 unlockClosure(msg, &stg_MSG_NULL_info);
153 -------------------------------------------------------------------------- */
156 throwTo (Capability *cap, // the Capability we hold
157 StgTSO *source, // the TSO sending the exception (or NULL)
158 StgTSO *target, // the TSO receiving the exception
159 StgClosure *exception) // the exception closure
163 msg = (MessageThrowTo *) allocate(cap, sizeofW(MessageThrowTo));
164 // message starts locked; the caller has to unlock it when it is
166 SET_HDR(msg, &stg_WHITEHOLE_info, CCS_SYSTEM);
167 msg->source = source;
168 msg->target = target;
169 msg->exception = exception;
171 switch (throwToMsg(cap, msg))
173 case THROWTO_SUCCESS:
175 case THROWTO_BLOCKED:
183 throwToMsg (Capability *cap, MessageThrowTo *msg)
186 StgTSO *target = msg->target;
187 Capability *target_cap;
193 debugTrace(DEBUG_sched, "throwTo: retrying...");
196 ASSERT(target != END_TSO_QUEUE);
198 // follow ThreadRelocated links in the target first
199 target = deRefTSO(target);
201 // Thread already dead?
202 if (target->what_next == ThreadComplete
203 || target->what_next == ThreadKilled) {
204 return THROWTO_SUCCESS;
207 debugTraceCap(DEBUG_sched, cap,
208 "throwTo: from thread %lu to thread %lu",
209 (unsigned long)msg->source->id,
210 (unsigned long)msg->target->id);
213 traceThreadStatus(DEBUG_sched, target);
216 target_cap = target->cap;
217 if (target->cap != cap) {
218 throwToSendMsg(cap, target_cap, msg);
219 return THROWTO_BLOCKED;
222 status = target->why_blocked;
227 if ((target->flags & TSO_BLOCKEX) == 0) {
228 // It's on our run queue and not blocking exceptions
229 raiseAsync(cap, target, msg->exception, rtsFalse, NULL);
230 return THROWTO_SUCCESS;
232 blockedThrowTo(cap,target,msg);
233 return THROWTO_BLOCKED;
237 case BlockedOnMsgThrowTo:
239 const StgInfoTable *i;
242 m = target->block_info.throwto;
244 // target is local to this cap, but has sent a throwto
245 // message to another cap.
247 // The source message is locked. We need to revoke the
248 // target's message so that we can raise the exception, so
249 // we attempt to lock it.
251 // There's a possibility of a deadlock if two threads are both
252 // trying to throwTo each other (or more generally, a cycle of
253 // threads). To break the symmetry we compare the addresses
254 // of the MessageThrowTo objects, and the one for which m <
255 // msg gets to spin, while the other can only try to lock
256 // once, but must then back off and unlock both before trying
259 i = lockClosure((StgClosure *)m);
261 i = tryLockClosure((StgClosure *)m);
263 // debugBelch("collision\n");
264 throwToSendMsg(cap, target->cap, msg);
265 return THROWTO_BLOCKED;
269 if (i == &stg_MSG_NULL_info) {
270 // we know there's a MSG_TRY_WAKEUP on the way, so we
271 // might as well just do it now. The message will
272 // be a no-op when it arrives.
273 unlockClosure((StgClosure*)m, i);
274 tryWakeupThread_(cap, target);
278 if (i != &stg_MSG_THROWTO_info) {
279 // if it's a MSG_NULL, this TSO has been woken up by another Cap
280 unlockClosure((StgClosure*)m, i);
284 if ((target->flags & TSO_BLOCKEX) &&
285 ((target->flags & TSO_INTERRUPTIBLE) == 0)) {
286 unlockClosure((StgClosure*)m, i);
287 blockedThrowTo(cap,target,msg);
288 return THROWTO_BLOCKED;
291 // nobody else can wake up this TSO after we claim the message
292 unlockClosure((StgClosure*)m, &stg_MSG_NULL_info);
294 raiseAsync(cap, target, msg->exception, rtsFalse, NULL);
295 return THROWTO_SUCCESS;
301 To establish ownership of this TSO, we need to acquire a
302 lock on the MVar that it is blocked on.
305 StgInfoTable *info USED_IF_THREADS;
307 mvar = (StgMVar *)target->block_info.closure;
309 // ASSUMPTION: tso->block_info must always point to a
310 // closure. In the threaded RTS it does.
311 switch (get_itbl(mvar)->type) {
319 info = lockClosure((StgClosure *)mvar);
321 if (target->what_next == ThreadRelocated) {
322 target = target->_link;
323 unlockClosure((StgClosure *)mvar,info);
326 // we have the MVar, let's check whether the thread
327 // is still blocked on the same MVar.
328 if (target->why_blocked != BlockedOnMVar
329 || (StgMVar *)target->block_info.closure != mvar) {
330 unlockClosure((StgClosure *)mvar, info);
334 if (target->_link == END_TSO_QUEUE) {
335 // the MVar operation has already completed. There is a
336 // MSG_TRY_WAKEUP on the way, but we can just wake up the
337 // thread now anyway and ignore the message when it
339 unlockClosure((StgClosure *)mvar, info);
340 tryWakeupThread_(cap, target);
344 if ((target->flags & TSO_BLOCKEX) &&
345 ((target->flags & TSO_INTERRUPTIBLE) == 0)) {
346 blockedThrowTo(cap,target,msg);
347 unlockClosure((StgClosure *)mvar, info);
348 return THROWTO_BLOCKED;
350 // revoke the MVar operation
351 removeFromMVarBlockedQueue(target);
352 raiseAsync(cap, target, msg->exception, rtsFalse, NULL);
353 unlockClosure((StgClosure *)mvar, info);
354 return THROWTO_SUCCESS;
358 case BlockedOnBlackHole:
360 // Revoke the message by replacing it with IND. We're not
361 // locking anything here, so we might still get a TRY_WAKEUP
362 // message from the owner of the blackhole some time in the
363 // future, but that doesn't matter.
364 ASSERT(target->block_info.bh->header.info == &stg_MSG_BLACKHOLE_info);
365 OVERWRITE_INFO(target->block_info.bh, &stg_IND_info);
366 raiseAsync(cap, target, msg->exception, rtsFalse, NULL);
367 return THROWTO_SUCCESS;
372 // Unblocking BlockedOnSTM threads requires the TSO to be
373 // locked; see STM.c:unpark_tso().
374 if (target->why_blocked != BlockedOnSTM) {
378 if ((target->flags & TSO_BLOCKEX) &&
379 ((target->flags & TSO_INTERRUPTIBLE) == 0)) {
380 blockedThrowTo(cap,target,msg);
382 return THROWTO_BLOCKED;
384 raiseAsync(cap, target, msg->exception, rtsFalse, NULL);
386 return THROWTO_SUCCESS;
390 case BlockedOnCCall_NoUnblockExc:
391 blockedThrowTo(cap,target,msg);
392 return THROWTO_BLOCKED;
394 #ifndef THREADEDED_RTS
398 #if defined(mingw32_HOST_OS)
399 case BlockedOnDoProc:
401 if ((target->flags & TSO_BLOCKEX) &&
402 ((target->flags & TSO_INTERRUPTIBLE) == 0)) {
403 blockedThrowTo(cap,target,msg);
404 return THROWTO_BLOCKED;
406 removeFromQueues(cap,target);
407 raiseAsync(cap, target, msg->exception, rtsFalse, NULL);
408 return THROWTO_SUCCESS;
413 barf("throwTo: unrecognised why_blocked value");
419 throwToSendMsg (Capability *cap STG_UNUSED,
420 Capability *target_cap USED_IF_THREADS,
421 MessageThrowTo *msg USED_IF_THREADS)
425 debugTraceCap(DEBUG_sched, cap, "throwTo: sending a throwto message to cap %lu", (unsigned long)target_cap->no);
427 sendMessage(cap, target_cap, (Message*)msg);
431 // Block a throwTo message on the target TSO's blocked_exceptions
432 // queue. The current Capability must own the target TSO in order to
433 // modify the blocked_exceptions queue.
435 blockedThrowTo (Capability *cap, StgTSO *target, MessageThrowTo *msg)
437 debugTraceCap(DEBUG_sched, cap, "throwTo: blocking on thread %lu",
438 (unsigned long)target->id);
440 ASSERT(target->cap == cap);
442 msg->link = target->blocked_exceptions;
443 target->blocked_exceptions = msg;
444 dirty_TSO(cap,target); // we modified the blocked_exceptions queue
447 /* -----------------------------------------------------------------------------
448 Waking up threads blocked in throwTo
450 There are two ways to do this: maybePerformBlockedException() will
451 perform the throwTo() for the thread at the head of the queue
452 immediately, and leave the other threads on the queue.
453 maybePerformBlockedException() also checks the TSO_BLOCKEX flag
454 before raising an exception.
456 awakenBlockedExceptionQueue() will wake up all the threads in the
457 queue, but not perform any throwTo() immediately. This might be
458 more appropriate when the target thread is the one actually running
461 Returns: non-zero if an exception was raised, zero otherwise.
462 -------------------------------------------------------------------------- */
465 maybePerformBlockedException (Capability *cap, StgTSO *tso)
468 const StgInfoTable *i;
470 if (tso->what_next == ThreadComplete || tso->what_next == ThreadFinished) {
471 if (tso->blocked_exceptions != END_BLOCKED_EXCEPTIONS_QUEUE) {
472 awakenBlockedExceptionQueue(cap,tso);
479 if (tso->blocked_exceptions != END_BLOCKED_EXCEPTIONS_QUEUE &&
480 (tso->flags & TSO_BLOCKEX) != 0) {
481 debugTraceCap(DEBUG_sched, cap, "throwTo: thread %lu has blocked exceptions but is inside block", (unsigned long)tso->id);
484 if (tso->blocked_exceptions != END_BLOCKED_EXCEPTIONS_QUEUE
485 && ((tso->flags & TSO_BLOCKEX) == 0
486 || ((tso->flags & TSO_INTERRUPTIBLE) && interruptible(tso)))) {
488 // We unblock just the first thread on the queue, and perform
489 // its throw immediately.
491 msg = tso->blocked_exceptions;
492 if (msg == END_BLOCKED_EXCEPTIONS_QUEUE) return 0;
493 i = lockClosure((StgClosure*)msg);
494 tso->blocked_exceptions = (MessageThrowTo*)msg->link;
495 if (i == &stg_MSG_NULL_info) {
496 unlockClosure((StgClosure*)msg,i);
500 throwToSingleThreaded(cap, msg->target, msg->exception);
501 unlockClosure((StgClosure*)msg,&stg_MSG_NULL_info);
502 tryWakeupThread(cap, msg->source);
508 // awakenBlockedExceptionQueue(): Just wake up the whole queue of
509 // blocked exceptions.
512 awakenBlockedExceptionQueue (Capability *cap, StgTSO *tso)
515 const StgInfoTable *i;
517 for (msg = tso->blocked_exceptions; msg != END_BLOCKED_EXCEPTIONS_QUEUE;
518 msg = (MessageThrowTo*)msg->link) {
519 i = lockClosure((StgClosure *)msg);
520 if (i != &stg_MSG_NULL_info) {
521 unlockClosure((StgClosure *)msg,&stg_MSG_NULL_info);
522 tryWakeupThread(cap, msg->source);
524 unlockClosure((StgClosure *)msg,i);
527 tso->blocked_exceptions = END_BLOCKED_EXCEPTIONS_QUEUE;
530 /* -----------------------------------------------------------------------------
531 Remove a thread from blocking queues.
533 This is for use when we raise an exception in another thread, which
536 Precondition: we have exclusive access to the TSO, via the same set
537 of conditions as throwToSingleThreaded() (c.f.).
538 -------------------------------------------------------------------------- */
541 removeFromMVarBlockedQueue (StgTSO *tso)
543 StgMVar *mvar = (StgMVar*)tso->block_info.closure;
544 StgMVarTSOQueue *q = (StgMVarTSOQueue*)tso->_link;
546 if (q == (StgMVarTSOQueue*)END_TSO_QUEUE) {
547 // already removed from this MVar
551 // Assume the MVar is locked. (not assertable; sometimes it isn't
552 // actually WHITEHOLE'd).
554 // We want to remove the MVAR_TSO_QUEUE object from the queue. It
555 // isn't doubly-linked so we can't actually remove it; instead we
556 // just overwrite it with an IND if possible and let the GC short
557 // it out. However, we have to be careful to maintain the deque
560 if (mvar->head == q) {
561 mvar->head = q->link;
562 q->header.info = &stg_IND_info;
563 if (mvar->tail == q) {
564 mvar->tail = (StgMVarTSOQueue*)END_TSO_QUEUE;
567 else if (mvar->tail == q) {
568 // we can't replace it with an IND in this case, because then
569 // we lose the tail pointer when the GC shorts out the IND.
570 // So we use MSG_NULL as a kind of non-dupable indirection;
571 // these are ignored by takeMVar/putMVar.
572 q->header.info = &stg_MSG_NULL_info;
575 q->header.info = &stg_IND_info;
578 // revoke the MVar operation
579 tso->_link = END_TSO_QUEUE;
583 removeFromQueues(Capability *cap, StgTSO *tso)
585 switch (tso->why_blocked) {
588 case ThreadMigrating:
592 // Be careful: nothing to do here! We tell the scheduler that the
593 // thread is runnable and we leave it to the stack-walking code to
594 // abort the transaction while unwinding the stack. We should
595 // perhaps have a debugging test to make sure that this really
596 // happens and that the 'zombie' transaction does not get
601 removeFromMVarBlockedQueue(tso);
604 case BlockedOnBlackHole:
608 case BlockedOnMsgThrowTo:
610 MessageThrowTo *m = tso->block_info.throwto;
611 // The message is locked by us, unless we got here via
612 // deleteAllThreads(), in which case we own all the
614 // ASSERT(m->header.info == &stg_WHITEHOLE_info);
616 // unlock and revoke it at the same time
617 unlockClosure((StgClosure*)m,&stg_MSG_NULL_info);
621 #if !defined(THREADED_RTS)
624 #if defined(mingw32_HOST_OS)
625 case BlockedOnDoProc:
627 removeThreadFromDeQueue(cap, &blocked_queue_hd, &blocked_queue_tl, tso);
628 #if defined(mingw32_HOST_OS)
629 /* (Cooperatively) signal that the worker thread should abort
632 abandonWorkRequest(tso->block_info.async_result->reqID);
637 removeThreadFromQueue(cap, &sleeping_queue, tso);
642 barf("removeFromQueues: %d", tso->why_blocked);
646 tso->why_blocked = NotBlocked;
647 appendToRunQueue(cap, tso);
650 /* -----------------------------------------------------------------------------
653 * The following function implements the magic for raising an
654 * asynchronous exception in an existing thread.
656 * We first remove the thread from any queue on which it might be
657 * blocked. The possible blockages are MVARs, BLOCKING_QUEUESs, and
658 * TSO blocked_exception queues.
660 * We strip the stack down to the innermost CATCH_FRAME, building
661 * thunks in the heap for all the active computations, so they can
662 * be restarted if necessary. When we reach a CATCH_FRAME, we build
663 * an application of the handler to the exception, and push it on
664 * the top of the stack.
666 * How exactly do we save all the active computations? We create an
667 * AP_STACK for every UpdateFrame on the stack. Entering one of these
668 * AP_STACKs pushes everything from the corresponding update frame
669 * upwards onto the stack. (Actually, it pushes everything up to the
670 * next update frame plus a pointer to the next AP_STACK object.
671 * Entering the next AP_STACK object pushes more onto the stack until we
672 * reach the last AP_STACK object - at which point the stack should look
673 * exactly as it did when we killed the TSO and we can continue
674 * execution by entering the closure on top of the stack.
676 * We can also kill a thread entirely - this happens if either (a) the
677 * exception passed to raiseAsync is NULL, or (b) there's no
678 * CATCH_FRAME on the stack. In either case, we strip the entire
679 * stack and replace the thread with a zombie.
681 * ToDo: in THREADED_RTS mode, this function is only safe if either
682 * (a) we hold all the Capabilities (eg. in GC, or if there is only
683 * one Capability), or (b) we own the Capability that the TSO is
684 * currently blocked on or on the run queue of.
686 * -------------------------------------------------------------------------- */
689 raiseAsync(Capability *cap, StgTSO *tso, StgClosure *exception,
690 rtsBool stop_at_atomically, StgUpdateFrame *stop_here)
692 StgRetInfoTable *info;
697 debugTraceCap(DEBUG_sched, cap,
698 "raising exception in thread %ld.", (long)tso->id);
700 #if defined(PROFILING)
702 * Debugging tool: on raising an exception, show where we are.
703 * See also Exception.cmm:stg_raisezh.
704 * This wasn't done for asynchronous exceptions originally; see #1450
706 if (RtsFlags.ProfFlags.showCCSOnException)
708 fprintCCS_stderr(tso->prof.CCCS);
711 // ASSUMES: the thread is not already complete or dead, or
712 // ThreadRelocated. Upper layers should deal with that.
713 ASSERT(tso->what_next != ThreadComplete &&
714 tso->what_next != ThreadKilled &&
715 tso->what_next != ThreadRelocated);
717 // only if we own this TSO (except that deleteThread() calls this
718 ASSERT(tso->cap == cap);
721 if (tso->why_blocked != NotBlocked) {
722 tso->why_blocked = NotBlocked;
723 appendToRunQueue(cap,tso);
726 // mark it dirty; we're about to change its stack.
731 if (stop_here != NULL) {
732 updatee = stop_here->updatee;
737 // The stack freezing code assumes there's a closure pointer on
738 // the top of the stack, so we have to arrange that this is the case...
740 if (sp[0] == (W_)&stg_enter_info) {
744 sp[0] = (W_)&stg_dummy_ret_closure;
748 while (stop_here == NULL || frame < (StgPtr)stop_here) {
750 // 1. Let the top of the stack be the "current closure"
752 // 2. Walk up the stack until we find either an UPDATE_FRAME or a
755 // 3. If it's an UPDATE_FRAME, then make an AP_STACK containing the
756 // current closure applied to the chunk of stack up to (but not
757 // including) the update frame. This closure becomes the "current
758 // closure". Go back to step 2.
760 // 4. If it's a CATCH_FRAME, then leave the exception handler on
761 // top of the stack applied to the exception.
763 // 5. If it's a STOP_FRAME, then kill the thread.
765 // NB: if we pass an ATOMICALLY_FRAME then abort the associated
768 info = get_ret_itbl((StgClosure *)frame);
770 switch (info->i.type) {
777 // First build an AP_STACK consisting of the stack chunk above the
778 // current update frame, with the top word on the stack as the
781 words = frame - sp - 1;
782 ap = (StgAP_STACK *)allocate(cap,AP_STACK_sizeW(words));
785 ap->fun = (StgClosure *)sp[0];
787 for(i=0; i < (nat)words; ++i) {
788 ap->payload[i] = (StgClosure *)*sp++;
791 SET_HDR(ap,&stg_AP_STACK_info,
792 ((StgClosure *)frame)->header.prof.ccs /* ToDo */);
793 TICK_ALLOC_UP_THK(words+1,0);
795 //IF_DEBUG(scheduler,
796 // debugBelch("sched: Updating ");
797 // printPtr((P_)((StgUpdateFrame *)frame)->updatee);
798 // debugBelch(" with ");
799 // printObj((StgClosure *)ap);
802 if (((StgUpdateFrame *)frame)->updatee == updatee) {
803 // If this update frame points to the same closure as
804 // the update frame further down the stack
805 // (stop_here), then don't perform the update. We
806 // want to keep the blackhole in this case, so we can
807 // detect and report the loop (#2783).
808 ap = (StgAP_STACK*)updatee;
810 // Perform the update
811 // TODO: this may waste some work, if the thunk has
812 // already been updated by another thread.
813 updateThunk(cap, tso,
814 ((StgUpdateFrame *)frame)->updatee, (StgClosure *)ap);
817 sp += sizeofW(StgUpdateFrame) - 1;
818 sp[0] = (W_)ap; // push onto stack
820 continue; //no need to bump frame
825 // We've stripped the entire stack, the thread is now dead.
826 tso->what_next = ThreadKilled;
827 tso->sp = frame + sizeofW(StgStopFrame);
832 // If we find a CATCH_FRAME, and we've got an exception to raise,
833 // then build the THUNK raise(exception), and leave it on
834 // top of the CATCH_FRAME ready to enter.
838 StgCatchFrame *cf = (StgCatchFrame *)frame;
842 if (exception == NULL) break;
844 // we've got an exception to raise, so let's pass it to the
845 // handler in this frame.
847 raise = (StgThunk *)allocate(cap,sizeofW(StgThunk)+1);
848 TICK_ALLOC_SE_THK(1,0);
849 SET_HDR(raise,&stg_raise_info,cf->header.prof.ccs);
850 raise->payload[0] = exception;
852 // throw away the stack from Sp up to the CATCH_FRAME.
856 /* Ensure that async excpetions are blocked now, so we don't get
857 * a surprise exception before we get around to executing the
860 tso->flags |= TSO_BLOCKEX | TSO_INTERRUPTIBLE;
862 /* Put the newly-built THUNK on top of the stack, ready to execute
863 * when the thread restarts.
866 sp[-1] = (W_)&stg_enter_info;
868 tso->what_next = ThreadRunGHC;
869 IF_DEBUG(sanity, checkTSO(tso));
873 case ATOMICALLY_FRAME:
874 if (stop_at_atomically) {
875 ASSERT(tso->trec->enclosing_trec == NO_TREC);
876 stmCondemnTransaction(cap, tso -> trec);
878 // The ATOMICALLY_FRAME expects to be returned a
879 // result from the transaction, which it stores in the
880 // stack frame. Hence we arrange to return a dummy
881 // result, so that the GC doesn't get upset (#3578).
882 // Perhaps a better way would be to have a different
883 // ATOMICALLY_FRAME instance for condemned
884 // transactions, but I don't fully understand the
885 // interaction with STM invariants.
886 tso->sp[1] = (W_)&stg_NO_TREC_closure;
887 tso->sp[0] = (W_)&stg_gc_unpt_r1_info;
888 tso->what_next = ThreadRunGHC;
891 // Not stop_at_atomically... fall through and abort the
894 case CATCH_STM_FRAME:
895 case CATCH_RETRY_FRAME:
896 // IF we find an ATOMICALLY_FRAME then we abort the
897 // current transaction and propagate the exception. In
898 // this case (unlike ordinary exceptions) we do not care
899 // whether the transaction is valid or not because its
900 // possible validity cannot have caused the exception
901 // and will not be visible after the abort.
904 StgTRecHeader *trec = tso -> trec;
905 StgTRecHeader *outer = trec -> enclosing_trec;
906 debugTraceCap(DEBUG_stm, cap,
907 "found atomically block delivering async exception");
908 stmAbortTransaction(cap, trec);
909 stmFreeAbortedTRec(cap, trec);
918 // move on to the next stack frame
919 frame += stack_frame_sizeW((StgClosure *)frame);
922 // if we got here, then we stopped at stop_here
923 ASSERT(stop_here != NULL);