Introduce gsync-based locks to glibc.

From: Agustina Arzille <avarzille@riseup.net>

* hurd/Makefile: Add hurdlock.
* hurd/Versions: Added new entry to export the above interface.
* hurd/hurdlock.c: New file.
* hurd/hurdlock.h: New file.
* hurd/hurdpid.c: Include <lowlevellock.h>
  (_S_msg_proc_newids): Use lll_wait to synchronize.
* hurd/hurdsig.c: (reauth_proc): Use __mutex_lock and __mutex_unlock.
* hurd/setauth.c: Include <hurdlock.h>, use integer for synchronization.
* hurd/sysvshm.c: Include <hurdlock.h>, use integer for synchronization.
* mach/Makefile: Remove unneeded file
* mach/lock-intern.h: Use lll to implement spinlocks.
* mach/lowlevellock.h: New file
* mach/mutex-init.c: Rewrite mutex initialization.
* sysdeps/mach/Makefile: Add libmachuser as dependencies for some libs.
* sysdeps/mach/bits/libc-lock.h: Reimplemented libc internal locks
  with lll, cleanup routines now use gcc's cleanup attribute
* sysdeps/mach/hurd/bits/errno.h: New errno values.
* sysdeps/mach/hurd/bits/libc-lock.h: Removed file.
* sysdeps/mach/hurd/malloc-machine.h: Reimplemented malloc locks.
* sysdeps/mach/hurd/setpgid.c: (setpgid): Use gsync for synchronization.
* sysdeps/mach/hurd/setsid.c: (setsid): Likewise.

4 files changed, 134 insertions, 39 deletions

diff --git a/mach/Makefile b/mach/Makefile
index 51ba0765be..d76f751cc0 100644
--- a/mach/Makefile
+++ b/mach/Makefile
@@ -23,7 +23,7 @@ headers = mach_init.h mach.h mach_error.h mach-shortcuts.h mach/mach_traps.h \
 	  $(interface-headers) mach/mach.h mach/mig_support.h mach/error.h \
 	  $(lock-headers) machine-sp.h
 lock = spin-solid spin-lock mutex-init mutex-solid
-lock-headers = lock-intern.h machine-lock.h spin-lock.h
+lock-headers = lock-intern.h spin-lock.h
 routines = $(mach-syscalls) $(mach-shortcuts) \
 	   mach_init mig_strncpy msg \
 	   mig-alloc mig-dealloc mig-reply \
diff --git a/mach/lock-intern.h b/mach/lock-intern.h
index df3d1c4e2f..c69a7ed425 100644
--- a/mach/lock-intern.h
+++ b/mach/lock-intern.h
@@ -19,73 +19,92 @@
 #define	_LOCK_INTERN_H
 
 #include <sys/cdefs.h>
-#include <machine-lock.h>
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+#include <lowlevellock.h>
+#endif
 
 #ifndef _EXTERN_INLINE
 #define _EXTERN_INLINE __extern_inline
 #endif
 
+/* The type of a spin lock variable. */
+typedef unsigned int __spin_lock_t;
+
+/* Static initializer for spinlocks. */
+#define __SPIN_LOCK_INITIALIZER   0
 
 /* Initialize LOCK.  */
 
 void __spin_lock_init (__spin_lock_t *__lock);
 
-#ifdef __USE_EXTERN_INLINES
+#if defined __USE_EXTERN_INLINES && defined _LIBC
 _EXTERN_INLINE void
 __spin_lock_init (__spin_lock_t *__lock)
 {
-  *__lock = __SPIN_LOCK_INITIALIZER;
+  *__lock = LLL_INITIALIZER;
 }
 #endif
 
 
-/* Lock LOCK, blocking if we can't get it.  */
-extern void __spin_lock_solid (__spin_lock_t *__lock);
-
 /* Lock the spin lock LOCK.  */
 
 void __spin_lock (__spin_lock_t *__lock);
 
-#ifdef __USE_EXTERN_INLINES
+#if defined __USE_EXTERN_INLINES && defined _LIBC
 _EXTERN_INLINE void
 __spin_lock (__spin_lock_t *__lock)
 {
-  if (! __spin_try_lock (__lock))
-    __spin_lock_solid (__lock);
+  lll_lock (__lock, 0);
 }
 #endif
-
-/* Name space-clean internal interface to mutex locks.
 
-   Code internal to the C library uses these functions to lock and unlock
-   mutex locks.  These locks are of type `struct mutex', defined in
-   <cthreads.h>.  The functions here are name space-clean.  If the program
-   is linked with the cthreads library, `__mutex_lock_solid' and
-   `__mutex_unlock_solid' will invoke the corresponding cthreads functions
-   to implement real mutex locks.  If not, simple stub versions just use
-   spin locks.  */
+/* Unlock LOCK. */
+void __spin_unlock (__spin_lock_t *__lock);
 
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+_EXTERN_INLINE void
+__spin_unlock (__spin_lock_t *__lock)
+{
+  lll_unlock (__lock, 0);
+}
+#endif
 
-/* Initialize the newly allocated mutex lock LOCK for further use.  */
-extern void __mutex_init (void *__lock);
+/* Try to lock LOCK; return nonzero if we locked it, zero if another has. */
+int __spin_try_lock (__spin_lock_t *__lock);
 
-/* Lock LOCK, blocking if we can't get it.  */
-extern void __mutex_lock_solid (void *__lock);
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+_EXTERN_INLINE int
+__spin_try_lock (__spin_lock_t *__lock)
+{
+  return (lll_trylock (__lock) == 0);
+}
+#endif
+
+/* Return nonzero if LOCK is locked. */
+int __spin_lock_locked (__spin_lock_t *__lock);
 
-/* Finish unlocking LOCK, after the spin lock LOCK->held has already been
-   unlocked.  This function will wake up any thread waiting on LOCK.  */
-extern void __mutex_unlock_solid (void *__lock);
+#if defined __USE_EXTERN_INLINES && defined _LIBC
+_EXTERN_INLINE int
+__spin_lock_locked (__spin_lock_t *__lock)
+{
+  return (*(volatile __spin_lock_t *)__lock != 0);
+}
+#endif
+
+/* Name space-clean internal interface to mutex locks. */
+
+/* Initialize the newly allocated mutex lock LOCK for further use.  */
+extern void __mutex_init (void *__lock);
 
 /* Lock the mutex lock LOCK.  */
 
 void __mutex_lock (void *__lock);
 
-#ifdef __USE_EXTERN_INLINES
+#if defined __USE_EXTERN_INLINES && defined _LIBC
 _EXTERN_INLINE void
 __mutex_lock (void *__lock)
 {
-  if (! __spin_try_lock ((__spin_lock_t *) __lock))
-    __mutex_lock_solid (__lock);
+  __spin_lock ((__spin_lock_t *)__lock);
 }
 #endif
 
@@ -93,23 +112,22 @@ __mutex_lock (void *__lock)
 
 void __mutex_unlock (void *__lock);
 
-#ifdef __USE_EXTERN_INLINES
+#if defined __USE_EXTERN_INLINES && defined _LIBC
 _EXTERN_INLINE void
 __mutex_unlock (void *__lock)
 {
-  __spin_unlock ((__spin_lock_t *) __lock);
-  __mutex_unlock_solid (__lock);
+  __spin_unlock ((__spin_lock_t *)__lock);
 }
 #endif
 
 
 int __mutex_trylock (void *__lock);
 
-#ifdef __USE_EXTERN_INLINES
+#if defined __USE_EXTERN_INLINES && defined _LIBC
 _EXTERN_INLINE int
 __mutex_trylock (void *__lock)
 {
-  return __spin_try_lock ((__spin_lock_t *) __lock);
+  return (__spin_try_lock ((__spin_lock_t *)__lock));
 }
 #endif
 
diff --git a/mach/lowlevellock.h b/mach/lowlevellock.h
new file mode 100644
index 0000000000..b6ce93927b
--- /dev/null
+++ b/mach/lowlevellock.h
@@ -0,0 +1,80 @@
+/* Copyright (C) 1994-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef __MACH_LOWLEVELLOCK_H__
+#define __MACH_LOWLEVELLOCK_H__   1
+
+#include <mach/gnumach.h>
+#include <atomic.h>
+
+/* Gsync flags. */
+#ifndef GSYNC_SHARED
+  #define GSYNC_SHARED      0x01
+  #define GSYNC_QUAD        0x02
+  #define GSYNC_TIMED       0x04
+  #define GSYNC_BROADCAST   0x08
+  #define GSYNC_MUTATE      0x10
+#endif
+
+/* Static initializer for low-level locks. */
+#define LLL_INITIALIZER   0
+
+/* Wait on address PTR, without blocking if its contents
+ * are different from VAL. */
+#define lll_wait(ptr, val, flags)   \
+  __gsync_wait (__mach_task_self (),   \
+    (vm_offset_t)(ptr), (val), 0, 0, (flags))
+
+/* Wake one or more threads waiting on address PTR. */
+#define lll_wake(ptr, flags)   \
+  __gsync_wake (__mach_task_self (), (vm_offset_t)(ptr), 0, (flags))
+
+/* Acquire the lock at PTR. */
+#define lll_lock(ptr, flags)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     int __flags = (flags);   \
+     if (*__iptr != 0 ||   \
+         atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) != 0)   \
+       while (1)   \
+         {   \
+           if (atomic_exchange_acq (__iptr, 2) == 0)   \
+             break;   \
+           lll_wait (__iptr, 2, __flags);   \
+         }   \
+     (void)0;   \
+   })
+
+/* Try to acquire the lock at PTR, without blocking.
+ * Evaluates to zero on success. */
+#define lll_trylock(ptr)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     *__iptr == 0 &&   \
+       atomic_compare_and_exchange_bool_acq (__iptr, 1, 0) == 0 ? 0 : -1;   \
+   })
+
+/* Release the lock at PTR. */
+#define lll_unlock(ptr, flags)   \
+  ({   \
+     int *__iptr = (int *)(ptr);   \
+     if (atomic_exchange_rel (__iptr, 0) == 2)   \
+       lll_wake (__iptr, (flags));   \
+     (void)0;   \
+   })
+
+#endif
diff --git a/mach/mutex-init.c b/mach/mutex-init.c
index c68320d1dd..cb9ba0e33c 100644
--- a/mach/mutex-init.c
+++ b/mach/mutex-init.c
@@ -17,13 +17,10 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <lock-intern.h>
-#include <cthreads.h>
+#include <lowlevellock.h>
 
 void
 __mutex_init (void *lock)
 {
-  /* This happens to be name space-safe because it is a macro.
-     It invokes only spin_lock_init, which is a macro for __spin_lock_init;
-     and cthread_queue_init, which is a macro for some simple code.  */
-  mutex_init ((struct mutex *) lock);
+  *(int *)lock = LLL_INITIALIZER;
 }