[project @ 2003-01-25 15:54:48 by wolfgang]

[ghc-hetmet.git] / ghc / rts / Interpreter.c

diff --git a/ghc/rts/Interpreter.c b/ghc/rts/Interpreter.c
index d39becb..270feb0 100644 (file)
--- a/ghc/rts/Interpreter.c
+++ b/ghc/rts/Interpreter.c
@@ -1157,6 +1157,7 @@ run_BCO:
            int stk_offset            = BCO_NEXT;
            int o_itbl                = BCO_NEXT;
            void(*marshall_fn)(void*) = (void (*)(void*))BCO_LIT(o_itbl);
+           StgTSO *tso               = cap->r.rCurrentTSO;
 
            // There are a bunch of non-ptr words on the stack (the
            // ccall args, the ccall fun address and space for the
@@ -1175,12 +1176,17 @@ run_BCO:
            SAVE_STACK_POINTERS;
            tok = suspendThread(&cap->r,rtsFalse);
 
-           // Careful: suspendThread might have shifted the stack
+           // Careful:
+           // suspendThread might have shifted the stack
            // around (stack squeezing), so we have to grab the real
-           // Sp out of the TSO to find the ccall args again:
-           marshall_fn ( (void*)(cap->r.rCurrentTSO->sp + RET_DYN_SIZE
-               + sizeofW(StgRetDyn)) );
-
+           // Sp out of the TSO to find the ccall args again.
+           // We don't own the capability anymore, so we mustn't use it.
+           // Instead, we have to save the TSO ptr beforehand.
+           // Also note that GC may strike at any time now (from another thread).
+           // FIXME - DANGER!! Can GC move our TSO?
+           // If so, we have to copy the args elsewhere!
+           marshall_fn ( (void*)(tso->sp + RET_DYN_SIZE + sizeofW(StgRetDyn)) );
+                   
            // And restart the thread again, popping the RET_DYN frame.
            cap = (Capability *)((void *)resumeThread(tok,rtsFalse) - sizeof(StgFunTable));
            LOAD_STACK_POINTERS;