Install toplevel handler inside fork.

When rts is forked it doesn't update toplevel handler, so UserInterrupt
exception is sent to Thread1 that doesn't exist in forked process.

We install toplevel handler when fork so signal will be delivered to the
new main thread.

Fixes #12903

Reviewers: simonmar, austin, erikd, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2770

GHC Trac Issues: #12903

(cherry picked from commit 895a131f6e56847d9ebca2e9bfe19a3189e49d72)

9 files changed, 55 insertions, 1 deletions

diff --git a/includes/RtsAPI.h b/includes/RtsAPI.h
index 4748060dee..0e29c63b54 100644
--- a/includes/RtsAPI.h
+++ b/includes/RtsAPI.h
@@ -245,6 +245,10 @@ void rts_evalIO (/* inout */ Capability **,
                  /* in    */ HaskellObj p,
                  /* out */   HaskellObj *ret);
 
+void rts_evalStableIOMain (/* inout */ Capability **,
+                           /* in    */ HsStablePtr s,
+                           /* out */   HsStablePtr *ret);
+
 void rts_evalStableIO (/* inout */ Capability **,
                        /* in    */ HsStablePtr s,
                        /* out */   HsStablePtr *ret);
diff --git a/rts/Prelude.h b/rts/Prelude.h
index ae1e9cb266..444aa469ab 100644
--- a/rts/Prelude.h
+++ b/rts/Prelude.h
@@ -51,6 +51,7 @@ PRELUDE_CLOSURE(base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure);
 PRELUDE_CLOSURE(base_GHCziConcziSignal_runHandlersPtr_closure);
 
 PRELUDE_CLOSURE(base_GHCziTopHandler_flushStdHandles_closure);
+PRELUDE_CLOSURE(base_GHCziTopHandler_runMainIO_closure);
 
 PRELUDE_INFO(ghczmprim_GHCziTypes_Czh_static_info);
 PRELUDE_INFO(ghczmprim_GHCziTypes_Izh_static_info);
@@ -99,6 +100,7 @@ PRELUDE_INFO(base_GHCziStable_StablePtr_con_info);
 #define runHandlersPtr_closure       DLL_IMPORT_DATA_REF(base_GHCziConcziSignal_runHandlersPtr_closure)
 
 #define flushStdHandles_closure   DLL_IMPORT_DATA_REF(base_GHCziTopHandler_flushStdHandles_closure)
+#define runMainIO_closure   DLL_IMPORT_DATA_REF(base_GHCziTopHandler_runMainIO_closure)
 
 #define stackOverflow_closure     DLL_IMPORT_DATA_REF(base_GHCziIOziException_stackOverflow_closure)
 #define heapOverflow_closure      DLL_IMPORT_DATA_REF(base_GHCziIOziException_heapOverflow_closure)
diff --git a/rts/RtsAPI.c b/rts/RtsAPI.c
index c64d8af2e4..47f6c93942 100644
--- a/rts/RtsAPI.c
+++ b/rts/RtsAPI.c
@@ -460,6 +460,35 @@ void rts_evalIO (/* inout */ Capability **cap,
 }
 
 /*
+ * rts_evalStableIOMain() is suitable for calling main Haskell thread
+ * stored in (StablePtr (IO a)) it calls rts_evalStableIO but wraps
+ * function in GHC.TopHandler.runMainIO that installs top_handlers.
+ * See Trac #12903.
+ */
+void rts_evalStableIOMain(/* inout */ Capability **cap,
+                          /* in    */ HsStablePtr s,
+                          /* out   */ HsStablePtr *ret)
+{
+    StgTSO* tso;
+    StgClosure *p, *r, *w;
+    SchedulerStatus stat;
+
+    p = (StgClosure *)deRefStablePtr(s);
+    w = rts_apply(*cap, &base_GHCziTopHandler_runMainIO_closure, p);
+    tso = createStrictIOThread(*cap, RtsFlags.GcFlags.initialStkSize, w);
+    // async exceptions are always blocked by default in the created
+    // thread.  See #1048.
+    tso->flags |= TSO_BLOCKEX | TSO_INTERRUPTIBLE;
+    scheduleWaitThread(tso,&r,cap);
+    stat = rts_getSchedStatus(*cap);
+
+    if (stat == Success && ret != NULL) {
+        ASSERT(r != NULL);
+        *ret = getStablePtr((StgPtr)r);
+    }
+}
+
+/*
  * rts_evalStableIO() is suitable for calling from Haskell.  It
  * evaluates a value of the form (StablePtr (IO a)), forcing the
  * action's result to WHNF before returning.  The result is returned
diff --git a/rts/RtsSymbols.c b/rts/RtsSymbols.c
index fec5cfc056..44b6591c35 100644
--- a/rts/RtsSymbols.c
+++ b/rts/RtsSymbols.c
@@ -647,6 +647,7 @@
       SymI_HasProto(rts_eval)                                           \
       SymI_HasProto(rts_evalIO)                                         \
       SymI_HasProto(rts_evalLazyIO)                                     \
+      SymI_HasProto(rts_evalStableIOMain)                               \
       SymI_HasProto(rts_evalStableIO)                                   \
       SymI_HasProto(rts_eval_)                                          \
       SymI_HasProto(rts_getBool)                                        \
diff --git a/rts/Schedule.c b/rts/Schedule.c
index 1f42e42417..33599d0abb 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -2078,7 +2078,10 @@ forkProcess(HsStablePtr *entry
         ioManagerStartCap(&cap);
 #endif
 
-        rts_evalStableIO(&cap, entry, NULL);  // run the action
+        // Install toplevel exception handlers, so interruption
+        // signal will be sent to the main thread.
+        // See Trac #12903
+        rts_evalStableIOMain(&cap, entry, NULL);  // run the action
         rts_checkSchedStatus("forkProcess",cap);
 
         rts_unlock(cap);
diff --git a/rts/package.conf.in b/rts/package.conf.in
index c0256bb028..e328be7b61 100644
--- a/rts/package.conf.in
+++ b/rts/package.conf.in
@@ -106,6 +106,7 @@ ld-options:
          , "-Wl,-u,_base_GHCziTopHandler_flushStdHandles_closure"
          , "-Wl,-u,_base_GHCziTopHandler_runIO_closure"
          , "-Wl,-u,_base_GHCziTopHandler_runNonIO_closure"
+         , "-Wl,-u,_base_GHCziTopHandler_runMainIO_closure"
          , "-Wl,-u,_base_GHCziConcziIO_ensureIOManagerIsRunning_closure"
          , "-Wl,-u,_base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure"
          , "-Wl,-u,_base_GHCziConcziSync_runSparks_closure"
@@ -148,6 +149,7 @@ ld-options:
          , "-Wl,-u,base_GHCziTopHandler_flushStdHandles_closure"
          , "-Wl,-u,base_GHCziTopHandler_runIO_closure"
          , "-Wl,-u,base_GHCziTopHandler_runNonIO_closure"
+         , "-Wl,-u,base_GHCziTopHandler_runMainIO_closure"
          , "-Wl,-u,base_GHCziConcziIO_ensureIOManagerIsRunning_closure"
          , "-Wl,-u,base_GHCziConcziIO_ioManagerCapabilitiesChanged_closure"
          , "-Wl,-u,base_GHCziConcziSync_runSparks_closure"
diff --git a/testsuite/tests/rts/T12903.hs b/testsuite/tests/rts/T12903.hs
new file mode 100644
index 0000000000..ddaf8b97e8
--- /dev/null
+++ b/testsuite/tests/rts/T12903.hs
@@ -0,0 +1,10 @@
+import Control.Concurrent
+import Control.Exception
+import System.Posix
+
+main = do
+  pid <- forkProcess $ do
+           handle (\UserInterrupt{} -> putStrLn "caught")
+                  $ threadDelay 2000000
+  signalProcess sigINT pid
+  threadDelay 2000000
diff --git a/testsuite/tests/rts/T12903.stdout b/testsuite/tests/rts/T12903.stdout
new file mode 100644
index 0000000000..cad99e1222
--- /dev/null
+++ b/testsuite/tests/rts/T12903.stdout
@@ -0,0 +1 @@
+caught
diff --git a/testsuite/tests/rts/all.T b/testsuite/tests/rts/all.T
index f7d518c311..d889276f1e 100644
--- a/testsuite/tests/rts/all.T
+++ b/testsuite/tests/rts/all.T
@@ -345,3 +345,5 @@ test('T10296b', [only_ways('threaded2')], compile_and_run, [''])
 test('T12497', [ unless(opsys('mingw32'), skip)
                ],
                run_command, ['$MAKE -s --no-print-directory T12497'])
+test('T12903', [ when(opsys('mingw32'), skip)], compile_and_run, [''])
+