2005-07-05 Ben Maurer <bmaurer@ximian.com>

	* pthread_stop_world.c (pthread_start_world, _GC_suspend_handler):
	Make sure that all threads have been started before releasing the
	GC_lock. Otherwise, the thread table can be corrupt in the restart
	handler, causing deadlocks and segfaults.

svn path=/trunk/mono/; revision=46962

diff --git a/ChangeLog b/ChangeLog
index 3393ebea2beb6b150456260f50dc0a095daf439b..80702c4ecb58573e2264ee6506b3bb680511a62b 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2005-07-05  Ben Maurer  <bmaurer@ximian.com>
+
+       * pthread_stop_world.c (pthread_start_world, _GC_suspend_handler):
+       Make sure that all threads have been started before releasing the
+       GC_lock. Otherwise, the thread table can be corrupt in the restart
+       handler, causing deadlocks and segfaults.
+
 2005-06-22  Zoltan Varga  <vargaz@freemail.hu>
 
        * include/private/gcconfig.h: Fix amd64 build.

diff --git a/pthread_stop_world.c b/pthread_stop_world.c
index 60a63d5d8ac0b75b3dda3a158cd9ba2ca292d4ca..68f1dce4306dbd5be23b66c688b45cc8320a766c 100644 (file)
--- a/pthread_stop_world.c
+++ b/pthread_stop_world.c
@@ -163,6 +163,12 @@ static void _GC_suspend_handler(int sig)
     /* to accidentally leave a RESTART signal pending, thus causing us to   */
     /* continue prematurely in a future round.                             */ 
 
+    /* Tell the thread that wants to start the world that this  */
+    /* thread has been started.  Note that sem_post() is       */
+    /* the only async-signal-safe primitive in LinuxThreads.    */
+    sem_post(&GC_suspend_ack_sem);
+
+
 #if DEBUG_THREADS
     GC_printf1("Continuing 0x%lx\n", my_thread);
 #endif
@@ -421,6 +427,7 @@ static void pthread_start_world()
     register GC_thread p;
     register int n_live_threads = 0;
     register int result;
+    int code;
 
 #   if DEBUG_THREADS
       GC_printf0("World starting\n");
@@ -450,6 +457,20 @@ static void pthread_start_world()
         }
       }
     }
+
+    #if DEBUG_THREADS
+    GC_printf0 ("All threads signaled");
+    #endif
+
+    for (i = 0; i < n_live_threads; i++) {
+       while (0 != (code = sem_wait(&GC_suspend_ack_sem))) {
+           if (errno != EINTR) {
+               GC_err_printf1("Sem_wait returned %ld\n", (unsigned long)code);
+               ABORT("sem_wait for handler failed");
+           }
+       }
+    }
+  
     #if DEBUG_THREADS
       GC_printf0("World started\n");
     #endif