X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FException.cmm;h=f35a9c7d1e32c5d4c80f710a797c3eb1bb121872;hb=85f3db842ae9bd547b3b21c18754b4987335fd38;hp=6192f6d77637b4882d14b522427421de3ca399f1;hpb=03d63424f3034c34d61fe0f654e05d20c9eded89;p=ghc-hetmet.git

diff --git a/ghc/rts/Exception.cmm b/ghc/rts/Exception.cmm
index 6192f6d..f35a9c7 100644
--- a/ghc/rts/Exception.cmm
+++ b/ghc/rts/Exception.cmm
@@ -35,12 +35,25 @@
    it.  The action of unblocking exceptions in a thread will release all
    the threads waiting to deliver exceptions to that thread.
 
+   NB. there's a bug in here.  If a thread is inside an
+   unsafePerformIO, and inside blockAsyncExceptions# (there is an
+   unblockAsyncExceptions_ret on the stack), and it is blocked in an
+   interruptible operation, and it receives an exception, then the
+   unsafePerformIO thunk will be updated with a stack object
+   containing the unblockAsyncExceptions_ret frame.  Later, when
+   someone else evaluates this thunk, the blocked exception state is
+   not restored, and the result is that unblockAsyncExceptions_ret
+   will attempt to unblock exceptions in the current thread, but it'll
+   find that the CurrentTSO->blocked_exceptions is NULL.  Hence, we
+   work around this by checking for NULL in awakenBlockedQueue().
+
    -------------------------------------------------------------------------- */
 
 INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
  		0/*framesize*/, 0/*bitmap*/, RET_SMALL )
 {
-    ASSERT(StgTSO_blocked_exceptions(CurrentTSO) != NULL);
+    // Not true: see comments above
+    // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) != NULL);
 #if defined(GRAN) || defined(PAR)
     foreign "C" awakenBlockedQueue(StgTSO_blocked_exceptions(CurrentTSO) "ptr", 
 				   NULL "ptr"); 
@@ -61,7 +74,8 @@ INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
 INFO_TABLE_RET( stg_blockAsyncExceptionszh_ret,
   		0/*framesize*/, 0/*bitmap*/, RET_SMALL )
 {
-    ASSERT(StgTSO_blocked_exceptions(CurrentTSO) == NULL);
+    // Not true: see comments above
+    // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) == NULL);
     StgTSO_blocked_exceptions(CurrentTSO) = END_TSO_QUEUE;
 #ifdef REG_R1
     Sp_adj(1);
@@ -345,7 +359,7 @@ retry_pop_stack:
       W_ trec;
       W_ r;
       trec = StgTSO_trec(CurrentTSO);
-      r = foreign "C" stmValidateTransaction(trec "ptr");
+      r = foreign "C" stmValidateNestOfTransactions(trec "ptr");
       foreign "C" stmAbortTransaction(trec "ptr");
       StgTSO_trec(CurrentTSO) = NO_TREC;
       if (r) {
@@ -355,7 +369,7 @@ retry_pop_stack:
       } else {
         // Transaction was not valid: we retry the exception (otherwise continue
         // with a further call to raiseExceptionHelper)
-        "ptr" trec = foreign "C" stmStartTransaction(NO_TREC "ptr");
+        "ptr" trec = foreign "C" stmStartTransaction(BaseReg "ptr", NO_TREC "ptr");
         StgTSO_trec(CurrentTSO) = trec;
         R1 = StgAtomicallyFrame_code(Sp);
         Sp_adj(-1);