Fix #3429: a tricky race condition

[ghc-hetmet.git] / rts / Exception.cmm

diff --git a/rts/Exception.cmm b/rts/Exception.cmm
index 16b5d92..cd3f2bc 100644 (file)
--- a/rts/Exception.cmm
+++ b/rts/Exception.cmm
@@ -49,6 +49,8 @@ import ghczmprim_GHCziBool_True_closure;
 
    -------------------------------------------------------------------------- */
 
+STRING(stg_unblockAsync_err_str, "unblockAsyncExceptions#_ret")
+
 INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret, RET_SMALL )
 {
     CInt r;
@@ -81,6 +83,14 @@ INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret, RET_SMALL )
                 jump %ENTRY_CODE(Sp(0));
             }
         }
+        else {
+            /*
+               the thread might have been removed from the
+               blocked_exception list by someone else in the meantime.
+               Just restore the stack pointer and continue.  
+            */   
+            Sp_adj(2);
+        }
     }
 
     Sp_adj(1);