re PR gcov-profile/49484 (gcov crash if two(or more) forks happen at the same time)

2012-03-12  Richard Guenther  <rguenther@suse.de>

	* gthr.h (__GTHREAD_MUTEX_INIT_FUNCTION): Adjust specification.
	* gthr-posix.h (__GTHREAD_MUTEX_INIT_FUNCTION): Define.
	(__gthread_mutex_init_function): New function.
	* gthr-single.h (__GTHREAD_MUTEX_INIT_FUNCTION): Define.

	PR gcov/49484
	* libgcov.c: Include gthr.h.
	(__gcov_flush_mx): New global variable.
	(init_mx, init_mx_once): New functions.
	(__gcov_flush): Protect self with a mutex.
	(__gcov_fork): Re-initialize mutex after forking.
	* unwind-dw2-fde.c: Change condition under which to use
	__GTHREAD_MUTEX_INIT_FUNCTION.

From-SVN: r185231

libgcc/ChangeLog

@@ -1,3 +1,19 @@
+2012-03-12  Richard Guenther  <rguenther@suse.de>
+
+	* gthr.h (__GTHREAD_MUTEX_INIT_FUNCTION): Adjust specification.
+	* gthr-posix.h (__GTHREAD_MUTEX_INIT_FUNCTION): Define.
+	(__gthread_mutex_init_function): New function.
+	* gthr-single.h (__GTHREAD_MUTEX_INIT_FUNCTION): Define.
+
+	PR gcov/49484
+	* libgcov.c: Include gthr.h.
+	(__gcov_flush_mx): New global variable.
+	(init_mx, init_mx_once): New functions.
+	(__gcov_flush): Protect self with a mutex.
+	(__gcov_fork): Re-initialize mutex after forking.
+	* unwind-dw2-fde.c: Change condition under which to use
+	__GTHREAD_MUTEX_INIT_FUNCTION.
+
 2012-03-12  Tristan Gingold  <gingold@adacore.com>
 
 	* config/alpha/t-vms: Define HOST_LIBGCC2_CFLAGS.

libgcc/gthr-posix.h

@@ -63,6 +63,7 @@ typedef struct timespec __gthread_time_t;
 #define __GTHREAD_HAS_COND	1
 
 #define __GTHREAD_MUTEX_INIT PTHREAD_MUTEX_INITIALIZER
+#define __GTHREAD_MUTEX_INIT_FUNCTION __gthread_mutex_init_function
 #define __GTHREAD_ONCE_INIT PTHREAD_ONCE_INIT
 #if defined(PTHREAD_RECURSIVE_MUTEX_INITIALIZER)
 #define __GTHREAD_RECURSIVE_MUTEX_INIT PTHREAD_RECURSIVE_MUTEX_INITIALIZER
@@ -753,6 +754,14 @@ __gthread_mutex_init_function (__gthread_mutex_t *__mutex)
 }
 #endif
 
+static inline int
+__gthread_mutex_init_function (__gthread_mutex_t *__mutex)
+{
+  if (__gthread_active_p ())
+    return __gthrw_(pthread_mutex_init) (__mutex, NULL);
+  return 0;
+}
+
 static inline int
 __gthread_mutex_destroy (__gthread_mutex_t *__mutex)
 {

libgcc/gthr-single.h

@@ -36,6 +36,7 @@ typedef int __gthread_recursive_mutex_t;
 
 #define __GTHREAD_ONCE_INIT 0
 #define __GTHREAD_MUTEX_INIT 0
+#define __GTHREAD_MUTEX_INIT_FUNCTION (mx)
 #define __GTHREAD_RECURSIVE_MUTEX_INIT 0
 
 #define UNUSED __attribute__((unused))

libgcc/gthr.h

@@ -52,11 +52,12 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      		to initialize __gthread_mutex_t to get a fast
 		non-recursive mutex.
      __GTHREAD_MUTEX_INIT_FUNCTION
-     		some systems can't initialize a mutex without a
-		function call.  On such systems, define this to a
-		function which looks like this:
+		to initialize __gthread_mutex_t to get a fast
+		non-recursive mutex.
+		Define this to a function which looks like this:
 		  void __GTHREAD_MUTEX_INIT_FUNCTION (__gthread_mutex_t *)
-		Don't define __GTHREAD_MUTEX_INIT in this case
+     		Some systems can't initialize a mutex without a
+		function call.  Don't define __GTHREAD_MUTEX_INIT in this case.
      __GTHREAD_RECURSIVE_MUTEX_INIT
      __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
      		as above, but for a recursive mutex.

libgcc/libgcov.c

@@ -30,6 +30,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #include "coretypes.h"
 #include "tm.h"
 #include "libgcc_tm.h"
+#include "gthr.h"
 
 #if defined(inhibit_libc)
 #define IN_LIBGCOV (-1)
@@ -705,6 +706,25 @@ __gcov_init (struct gcov_info *info)
   info->version = 0;
 }
 
+#ifdef __GTHREAD_MUTEX_INIT
+ATTRIBUTE_HIDDEN __gthread_mutex_t __gcov_flush_mx = __GTHREAD_MUTEX_INIT;
+#define init_mx_once()
+#else
+__gthread_mutex_t __gcov_flush_mx ATTRIBUTE_HIDDEN;
+
+static void
+init_mx (void)
+{
+  __GTHREAD_MUTEX_INIT_FUNCTION (&mx);
+}
+static void
+init_mx_once (void)
+{
+  static __gthread_once_t once = __GTHREAD_ONCE_INIT;
+  __gthread_once (&once, init_mx);
+}
+#endif
+
 /* Called before fork or exec - write out profile information gathered so
    far and reset it to zero.  This avoids duplication or loss of the
    profile information gathered so far.  */
@@ -714,6 +734,9 @@ __gcov_flush (void)
 {
   const struct gcov_info *gi_ptr;
 
+  init_mx_once ();
+  __gthread_mutex_lock (&__gcov_flush_mx);
+
   gcov_exit ();
   for (gi_ptr = gcov_list; gi_ptr; gi_ptr = gi_ptr->next)
     {
@@ -737,6 +760,8 @@ __gcov_flush (void)
 	    }
 	}
     }
+
+  __gthread_mutex_unlock (&__gcov_flush_mx);
 }
 
 #endif /* L_gcov */
@@ -975,8 +1000,13 @@ __gcov_ior_profiler (gcov_type *counters, gcov_type value)
 pid_t
 __gcov_fork (void)
 {
+  pid_t pid;
+  extern __gthread_mutex_t __gcov_flush_mx;
   __gcov_flush ();
-  return fork ();
+  pid = fork ();
+  if (pid == 0)
+    __GTHREAD_MUTEX_INIT_FUNCTION (&__gcov_flush_mx);
+  return pid;
 }
 #endif
 

libgcc/unwind-dw2-fde.c

@@ -47,11 +47,10 @@ static struct object *seen_objects;
 
 #ifdef __GTHREAD_MUTEX_INIT
 static __gthread_mutex_t object_mutex = __GTHREAD_MUTEX_INIT;
+#define init_object_mutex_once()
 #else
 static __gthread_mutex_t object_mutex;
-#endif
 
-#ifdef __GTHREAD_MUTEX_INIT_FUNCTION
 static void
 init_object_mutex (void)
 {
@@ -64,8 +63,6 @@ init_object_mutex_once (void)
   static __gthread_once_t once = __GTHREAD_ONCE_INIT;
   __gthread_once (&once, init_object_mutex);
 }
-#else
-#define init_object_mutex_once()
 #endif
 
 /* Called from crtbegin.o to register the unwind info for an object.  */