From: Simon Marlow <simonmar@microsoft.com>
Date: Mon, 16 Oct 2006 11:17:41 +0000 (+0000)
Subject: Fix deadlock on second call to newSession
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=449b0be44b3bf53c7d817231df3e754278968440

Fix deadlock on second call to newSession
Tracked down by Krasimir Angelov
---

diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index 6295d7d..eabcafc 100644
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -333,7 +333,7 @@ newSession :: GhcMode -> Maybe FilePath -> IO Session
 newSession mode mb_top_dir = do
   -- catch ^C
   main_thread <- myThreadId
-  putMVar interruptTargetThread [main_thread]
+  modifyMVar_ interruptTargetThread (return . (main_thread :))
   installSignalHandlers
 
   dflags0 <- initSysTools mb_top_dir defaultDynFlags
diff --git a/compiler/utils/Panic.lhs b/compiler/utils/Panic.lhs
index 42bf8b5..eb3ce78 100644
--- a/compiler/utils/Panic.lhs
+++ b/compiler/utils/Panic.lhs
@@ -40,7 +40,7 @@ import GHC.ConsoleHandler
 #endif
 
 import Control.Exception hiding (try)
-import Control.Concurrent ( myThreadId, MVar, ThreadId, withMVar, newEmptyMVar )
+import Control.Concurrent ( myThreadId, MVar, ThreadId, withMVar, newMVar )
 import Data.Dynamic
 import qualified Control.Exception as Exception
 import Debug.Trace	( trace )
@@ -237,5 +237,5 @@ installSignalHandlers = do
 
 {-# NOINLINE interruptTargetThread #-}
 interruptTargetThread :: MVar [ThreadId]
-interruptTargetThread = unsafePerformIO newEmptyMVar
+interruptTargetThread = unsafePerformIO (newMVar [])
 \end{code}