Add _NEW flag to mtx(9), sx(9), rmlock(9) and rwlock(9).

A _NEW flag passed to _init_flags() to avoid check for double-init.

Differential Revision:	https://reviews.freebsd.org/D1208
Reviewed by:	jhb, wblock
MFC after:	1 Month

10 files changed, 25 insertions, 8 deletions

diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c
index d21be50..ea6f7a6 100644
--- a/sys/kern/kern_mutex.c
+++ b/sys/kern/kern_mutex.c
@@ -881,7 +881,7 @@ _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
 	m = mtxlock2mtx(c);
 
 	MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
-		MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0);
+	    MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
 	ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
 	    ("%s: mtx_lock not aligned for %s: %p", __func__, name,
 	    &m->mtx_lock));
@@ -907,6 +907,8 @@ _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
 		flags |= LO_DUPOK;
 	if (opts & MTX_NOPROFILE)
 		flags |= LO_NOPROFILE;
+	if (opts & MTX_NEW)
+		flags |= LO_NEW;
 
 	/* Initialize mutex. */
 	lock_init(&m->lock_object, class, name, type, flags);
diff --git a/sys/kern/kern_rmlock.c b/sys/kern/kern_rmlock.c
index d93aa15..b5ea2af 100644
--- a/sys/kern/kern_rmlock.c
+++ b/sys/kern/kern_rmlock.c
@@ -277,22 +277,28 @@ void
 rm_init_flags(struct rmlock *rm, const char *name, int opts)
 {
 	struct lock_class *lc;
-	int liflags;
+	int liflags, xflags;
 
 	liflags = 0;
 	if (!(opts & RM_NOWITNESS))
 		liflags |= LO_WITNESS;
 	if (opts & RM_RECURSE)
 		liflags |= LO_RECURSABLE;
+	if (opts & RM_NEW)
+		liflags |= LO_NEW;
 	rm->rm_writecpus = all_cpus;
 	LIST_INIT(&rm->rm_activeReaders);
 	if (opts & RM_SLEEPABLE) {
 		liflags |= LO_SLEEPABLE;
 		lc = &lock_class_rm_sleepable;
-		sx_init_flags(&rm->rm_lock_sx, "rmlock_sx", SX_NOWITNESS);
+		xflags = (opts & RM_NEW ? SX_NEW : 0);
+		sx_init_flags(&rm->rm_lock_sx, "rmlock_sx",
+		    xflags | SX_NOWITNESS);
 	} else {
 		lc = &lock_class_rm;
-		mtx_init(&rm->rm_lock_mtx, name, "rmlock_mtx", MTX_NOWITNESS);
+		xflags = (opts & RM_NEW ? MTX_NEW : 0);
+		mtx_init(&rm->rm_lock_mtx, name, "rmlock_mtx",
+		    xflags | MTX_NOWITNESS);
 	}
 	lock_init(&rm->lock_object, lc, name, NULL, liflags);
 }
diff --git a/sys/kern/kern_rwlock.c b/sys/kern/kern_rwlock.c
index c0906c0..d3cfbdd 100644
--- a/sys/kern/kern_rwlock.c
+++ b/sys/kern/kern_rwlock.c
@@ -187,7 +187,7 @@ _rw_init_flags(volatile uintptr_t *c, const char *name, int opts)
 	rw = rwlock2rw(c);
 
 	MPASS((opts & ~(RW_DUPOK | RW_NOPROFILE | RW_NOWITNESS | RW_QUIET |
-	    RW_RECURSE)) == 0);
+	    RW_RECURSE | RW_NEW)) == 0);
 	ASSERT_ATOMIC_LOAD_PTR(rw->rw_lock,
 	    ("%s: rw_lock not aligned for %s: %p", __func__, name,
 	    &rw->rw_lock));
@@ -203,6 +203,8 @@ _rw_init_flags(volatile uintptr_t *c, const char *name, int opts)
 		flags |= LO_RECURSABLE;
 	if (opts & RW_QUIET)
 		flags |= LO_QUIET;
+	if (opts & RW_NEW)
+		flags |= LO_NEW;
 
 	lock_init(&rw->lock_object, &lock_class_rw, name, NULL, flags);
 	rw->rw_lock = RW_UNLOCKED;
diff --git a/sys/kern/kern_sx.c b/sys/kern/kern_sx.c
index 6bd2760..a986590 100644
--- a/sys/kern/kern_sx.c
+++ b/sys/kern/kern_sx.c
@@ -209,7 +209,7 @@ sx_init_flags(struct sx *sx, const char *description, int opts)
 	int flags;
 
 	MPASS((opts & ~(SX_QUIET | SX_RECURSE | SX_NOWITNESS | SX_DUPOK |
-	    SX_NOPROFILE | SX_NOADAPTIVE)) == 0);
+	    SX_NOPROFILE | SX_NOADAPTIVE | SX_NEW)) == 0);
 	ASSERT_ATOMIC_LOAD_PTR(sx->sx_lock,
 	    ("%s: sx_lock not aligned for %s: %p", __func__, description,
 	    &sx->sx_lock));
@@ -225,6 +225,8 @@ sx_init_flags(struct sx *sx, const char *description, int opts)
 		flags |= LO_RECURSABLE;
 	if (opts & SX_QUIET)
 		flags |= LO_QUIET;
+	if (opts & SX_NEW)
+		flags |= LO_NEW;
 
 	flags |= opts & SX_NOADAPTIVE;
 	lock_init(&sx->lock_object, &lock_class_sx, description, NULL, flags);
diff --git a/sys/kern/subr_lock.c b/sys/kern/subr_lock.c
index ef13aee..e78d5a9 100644
--- a/sys/kern/subr_lock.c
+++ b/sys/kern/subr_lock.c
@@ -75,8 +75,8 @@ lock_init(struct lock_object *lock, struct lock_class *class, const char *name,
 	int i;
 
 	/* Check for double-init and zero object. */
-	KASSERT(!lock_initialized(lock), ("lock \"%s\" %p already initialized",
-	    name, lock));
+	KASSERT(flags & LO_NEW || !lock_initialized(lock),
+	    ("lock \"%s\" %p already initialized", name, lock));
 
 	/* Look up lock class to find its index. */
 	for (i = 0; i < LOCK_CLASS_MAX; i++)
diff --git a/sys/sys/lock.h b/sys/sys/lock.h
index e4b573a..8d7a068 100644
--- a/sys/sys/lock.h
+++ b/sys/sys/lock.h
@@ -84,6 +84,7 @@ struct lock_class {
 #define	LO_IS_VNODE	0x00800000	/* Tell WITNESS about a VNODE lock */
 #define	LO_CLASSMASK	0x0f000000	/* Class index bitmask. */
 #define LO_NOPROFILE    0x10000000      /* Don't profile this lock */
+#define	LO_NEW		0x20000000	/* Don't check for double-init */
 
 /*
  * Lock classes are statically assigned an index into the gobal lock_classes
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h
index 4678600..ec0c241 100644
--- a/sys/sys/mutex.h
+++ b/sys/sys/mutex.h
@@ -52,6 +52,7 @@
 #define MTX_RECURSE	0x00000004	/* Option: lock allowed to recurse */
 #define	MTX_NOWITNESS	0x00000008	/* Don't do any witness checking. */
 #define MTX_NOPROFILE   0x00000020	/* Don't profile this lock */
+#define	MTX_NEW		0x00000040	/* Don't check for double-init */
 
 /*
  * Option flags passed to certain lock/unlock routines, through the use
diff --git a/sys/sys/rmlock.h b/sys/sys/rmlock.h
index ed6110a..891fff1 100644
--- a/sys/sys/rmlock.h
+++ b/sys/sys/rmlock.h
@@ -45,6 +45,7 @@
 #define	RM_NOWITNESS	0x00000001
 #define	RM_RECURSE	0x00000002
 #define	RM_SLEEPABLE	0x00000004
+#define	RM_NEW		0x00000008
 
 void	rm_init(struct rmlock *rm, const char *name);
 void	rm_init_flags(struct rmlock *rm, const char *name, int opts);
diff --git a/sys/sys/rwlock.h b/sys/sys/rwlock.h
index a1fcb86..b638d3e 100644
--- a/sys/sys/rwlock.h
+++ b/sys/sys/rwlock.h
@@ -258,6 +258,7 @@ struct rw_args_flags {
 #define	RW_NOWITNESS	0x04
 #define	RW_QUIET	0x08
 #define	RW_RECURSE	0x10
+#define	RW_NEW		0x20
 
 /*
  * The INVARIANTS-enabled rw_assert() functionality.
diff --git a/sys/sys/sx.h b/sys/sys/sx.h
index 8e4a644..1da4356 100644
--- a/sys/sys/sx.h
+++ b/sys/sys/sx.h
@@ -292,6 +292,7 @@ __sx_sunlock(struct sx *sx, const char *file, int line)
 #define	SX_QUIET		0x08
 #define	SX_NOADAPTIVE		0x10
 #define	SX_RECURSE		0x20
+#define	SX_NEW			0x40
 
 /*
  * Options passed to sx_*lock_hard().