Properly interpose libc spinlocks, was missed in r276630. In

particular, stdio locking was affected.

Reported and tested by:	"Matthew D. Fuller" <fullermd@over-yonder.net>
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days

lib/libc/gen/_spinlock_stub.c

@@ -33,51 +33,48 @@ __FBSDID("$FreeBSD$");
 #include <stdio.h>
 
 #include "spinlock.h"
+#include "libc_private.h"
 
 long _atomic_lock_stub(volatile long *);
 void _spinlock_stub(spinlock_t *);
 void _spinunlock_stub(spinlock_t *);
 void _spinlock_debug_stub(spinlock_t *, char *, int);
 
-/*
- * Declare weak definitions in case the application is not linked
- * with libpthread.
- */
 __weak_reference(_atomic_lock_stub, _atomic_lock);
-__weak_reference(_spinlock_stub, _spinlock);
-__weak_reference(_spinunlock_stub, _spinunlock);
-__weak_reference(_spinlock_debug_stub, _spinlock_debug);
 
-/*
- * This function is a stub for the _atomic_lock function in libpthread.
- */
 long
 _atomic_lock_stub(volatile long *lck __unused)
 {
 	return (0L);
 }
 
-
-/*
- * This function is a stub for the spinlock function in libpthread.
- */
+__weak_reference(_spinlock, _spinlock_debug);
+#pragma weak _spinlock
 void
-_spinlock_stub(spinlock_t *lck __unused)
+_spinlock(spinlock_t *lck)
+{
+
+	((void (*)(spinlock_t *lck))__libc_interposing[INTERPOS_spinlock])
+	    (lck);
+
+}
+
+#pragma weak _spinlock
+void
+_spinunlock(spinlock_t *lck)
+{
+
+	((void (*)(spinlock_t *lck))__libc_interposing[INTERPOS_spinunlock])
+	    (lck);
+
+}
+
+void
+__libc_spinlock_stub(spinlock_t *lck __unused)
 {
 }
 
-/*
- * This function is a stub for the spinunlock function in libpthread.
- */
 void
-_spinunlock_stub(spinlock_t *lck __unused)
-{
-}
-
-/*
- * This function is a stub for the debug spinlock function in libpthread.
- */
-void
-_spinlock_debug_stub(spinlock_t *lck __unused, char *fname __unused, int lineno __unused)
+__libc_spinunlock_stub(spinlock_t *lck __unused)
 {
 }

lib/libc/include/libc_private.h

@@ -95,6 +95,9 @@ do {							\
 		_SPINUNLOCK(&__stdio_thread_lock);	\
 } while (0)
 
+void		__libc_spinlock_stub(struct _spinlock *);
+void		__libc_spinunlock_stub(struct _spinlock *);
+
 /*
  * Indexes into the pthread jump table.
  *
@@ -216,6 +219,8 @@ enum {
 	INTERPOS_write,
 	INTERPOS_writev,
 	INTERPOS__pthread_mutex_init_calloc_cb,
+	INTERPOS_spinlock,
+	INTERPOS_spinunlock,
 	INTERPOS_MAX
 };
 

lib/libc/sys/interposing_table.c

@@ -73,6 +73,8 @@ interpos_func_t __libc_interposing[INTERPOS_MAX] = {
 	SLOT(write, __sys_write),
 	SLOT(writev, __sys_writev),
 	SLOT(_pthread_mutex_init_calloc_cb, _pthread_mutex_init_calloc_cb_stub),
+	SLOT(spinlock, __libc_spinlock_stub),
+	SLOT(spinunlock, __libc_spinunlock_stub),
 };
 #undef SLOT
 

lib/libthr/thread/thr_private.h

@@ -928,6 +928,10 @@ int __thr_sigwait(const sigset_t *set, int *sig);
 int __thr_sigwaitinfo(const sigset_t *set, siginfo_t *info);
 int __thr_swapcontext(ucontext_t *oucp, const ucontext_t *ucp);
 
+struct _spinlock;
+void __thr_spinunlock(struct _spinlock *lck);
+void __thr_spinlock(struct _spinlock *lck);
+
 struct tcb *_tcb_ctor(struct pthread *, int);
 void	_tcb_dtor(struct tcb *);
 

lib/libthr/thread/thr_spinlock.c

@@ -61,7 +61,7 @@ static void	init_spinlock(spinlock_t *lck);
  */
 
 void
-_spinunlock(spinlock_t *lck)
+__thr_spinunlock(spinlock_t *lck)
 {
 	struct spinlock_extra	*_extra;
 
@@ -70,7 +70,7 @@ _spinunlock(spinlock_t *lck)
 }
 
 void
-_spinlock(spinlock_t *lck)
+__thr_spinlock(spinlock_t *lck)
 {
 	struct spinlock_extra *_extra;
 
@@ -84,12 +84,6 @@ _spinlock(spinlock_t *lck)
 	THR_UMUTEX_LOCK(_get_curthread(), &_extra->lock);
 }
 
-void
-_spinlock_debug(spinlock_t *lck, char *fname __unused, int lineno __unused)
-{
-	_spinlock(lck);
-}
-
 static void
 init_spinlock(spinlock_t *lck)
 {

lib/libthr/thread/thr_syscalls.c

@@ -597,6 +597,8 @@ __thr_interpose_libc(void)
 	SLOT(wait4);
 	SLOT(write);
 	SLOT(writev);
+	SLOT(spinlock);
+	SLOT(spinunlock);
 #undef SLOT
 	*(__libc_interposing_slot(
 	    INTERPOS__pthread_mutex_init_calloc_cb)) =