Re: [libgomp] Add Unix95 mutex support

[Eric Botcazou <ebotcazou at libertysurf dot fr>]

> > 	* configure.tgt: Pass -DLIBGOMP_UNIX95 to the compiler
> > 	and -lposix4 to the linker on Solaris 2.5.1 and 2.6.
>
> Style nit: Can use AC_DEFINE instead?
>
> In general I don't like this kind of configure checks.  Could it be
> possible to use AC_SEARCH_LIBS to look for pthread_mutex_init in -lposix4?

I thought configure.tgt was precisely aimed at getting rid of the configure 
mess?

> Second, I see that pthread_mutexattr_t is used unconditionally:
>
>     pthread_mutexattr_t attr;
>
> +#ifdef LIBGOMP_UNIX95
> +  pthread_mutex_init (&lock->lock, NULL);
> +#else
>     pthread_mutexattr_init (&attr);
>     pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
>     pthread_mutex_init (&lock->lock, &attr);
> -  lock->count = 0;
>     pthread_mutexattr_destroy (&attr);
> +#endif

You're right.  A more annoying problem is that lock->owner is not initialized.
I've attached a revised patch, retested on SPARC/Solaris 2.5.1.

> So, first this is going to give an uninitialized warning, and second we
> could make the code conditional on the existence of
> PTHREAD_MUTEX_RECURSIVE, or something like this:

Is PTHREAD_MUTEX_RECURSIVE guaranteed to be a macro?

> Finally, does it harm to define _XOPEN_SOURCE unconditionally for
> Solaris 2.5.1/2.6?

I think you cannot reasonably define _XOPEN_SOURCE to 500 for Unix95.

-- 
Eric Botcazou

Index: configure.tgt
===================================================================
--- configure.tgt	(revision 111111)
+++ configure.tgt	(working copy)
@@ -91,7 +91,9 @@ case "${target}" in
 	XLDFLAGS="${XLDFLAGS} -lrt"
 	;;
 
-  *)
+  *-*-solaris2.[56]*)
+	XCFLAGS="$(XCFLAGS) -DLIBGOMP_UNIX95"
+	XLDFLAGS="${XLDFLAGS} -lposix4"
 	;;
 
 esac
Index: config/posix/omp-lock.h
===================================================================
--- config/posix/omp-lock.h	(revision 111111)
+++ config/posix/omp-lock.h	(working copy)
@@ -8,4 +8,12 @@
 #include <pthread.h>
 
 typedef pthread_mutex_t omp_lock_t;
-typedef struct { pthread_mutex_t lock; int count; } omp_nest_lock_t;
+
+typedef struct
+{
+  pthread_mutex_t lock;
+#ifdef LIBGOMP_UNIX95
+  pthread_t owner;
+#endif
+  int count;
+} omp_nest_lock_t;
Index: config/posix/lock.c
===================================================================
--- config/posix/lock.c	(revision 111111)
+++ config/posix/lock.c	(working copy)
@@ -33,8 +33,10 @@
    to do better and streamline the locking as well as reduce the size
    of the types exported.  */
 
+#ifndef LIBGOMP_UNIX95
 /* We need Unix98 extensions to get recursive locks.  */
 #define _XOPEN_SOURCE 500
+#endif
 
 #include "libgomp.h"
 
@@ -72,13 +74,19 @@ omp_test_lock (omp_lock_t *lock)
 void
 omp_init_nest_lock (omp_nest_lock_t *lock)
 {
+#ifdef LIBGOMP_UNIX95
+  pthread_mutex_init (&lock->lock, NULL);
+  lock->owner = (pthread_t) 0;
+#else
   pthread_mutexattr_t attr;
 
   pthread_mutexattr_init (&attr);
   pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
   pthread_mutex_init (&lock->lock, &attr);
-  lock->count = 0;
   pthread_mutexattr_destroy (&attr);
+#endif
+
+  lock->count = 0;
 }
 
 void
@@ -90,7 +98,18 @@ omp_destroy_nest_lock (omp_nest_lock_t *
 void
 omp_set_nest_lock (omp_nest_lock_t *lock)
 {
+#ifdef LIBGOMP_UNIX95
+  pthread_t me = pthread_self ();
+
+  if (lock->owner != me)
+    {
+      pthread_mutex_lock (&lock->lock);
+      lock->owner = me;
+    }
+#else
   pthread_mutex_lock (&lock->lock);
+#endif
+
   lock->count++;
 }
 
@@ -98,15 +117,36 @@ void
 omp_unset_nest_lock (omp_nest_lock_t *lock)
 {
   lock->count--;
+
+#ifdef LIBGOMP_UNIX95
+  if (lock->count == 0)
+    {
+      lock->owner = (pthread_t) 0;
+      pthread_mutex_unlock (&lock->lock);
+    }
+#else
   pthread_mutex_unlock (&lock->lock);
+#endif
 }
 
 int
 omp_test_nest_lock (omp_nest_lock_t *lock)
 {
+#ifdef LIBGOMP_UNIX95
+  pthread_t me = pthread_self ();
+
+  if (lock->owner != me)
+    {
+      if (pthread_mutex_trylock (&lock->lock) != 0)
+	return 0;
+      lock->owner = me;
+    }
+  return ++lock->count;
+#else
   if (pthread_mutex_trylock (&lock->lock) == 0)
     return ++lock->count;
   return 0;
+#endif
 }
 
 ialias (omp_init_lock)