track lock class name in a way that doesn't break WITNESS

sys/kern/kern_lock.c

@@ -62,8 +62,19 @@ __FBSDID("$FreeBSD$");
 
 #ifdef DDB
 #include <ddb/ddb.h>
+static void	db_show_lockmgr(struct lock_object *lock);
 #endif
 
+
+struct lock_class lock_class_lockmgr = {
+	"lockmgr",
+	LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE | LC_UPGRADABLE,
+#ifdef DDB
+	db_show_lockmgr
+#endif
+};
+
+
 /*
  * Locking primitives implementation.
  * Locks provide shared/exclusive sychronization.
@@ -166,8 +177,6 @@ _lockmgr(struct lock *lkp, int flags, struct mtx *interlkp,
 		thr = td;
 
 	lock_profile_waitstart(&waitstart);
-
-	lkp->lk_object.lo_type = "lockmgr";
 	if ((flags & LK_INTERNAL) == 0)
 		mtx_lock(lkp->lk_interlock);
 	CTR6(KTR_LOCK,
@@ -523,7 +532,7 @@ lockinit(lkp, prio, wmesg, timo, flags)
 #ifdef DEBUG_LOCKS
 	stack_zero(&lkp->lk_stack);
 #endif
-	lock_profile_object_init(&lkp->lk_object, wmesg);
+	lock_profile_object_init(&lkp->lk_object, &lock_class_lockmgr, wmesg);
 }
 
 /*
@@ -648,14 +657,13 @@ lockmgr_chain(struct thread *td, struct thread **ownerp)
 	return (1);
 }
 
-DB_SHOW_COMMAND(lockmgr, db_show_lockmgr)
+void
+db_show_lockmgr(struct lock_object *lock)
 {
 	struct thread *td;
 	struct lock *lkp;
 
-	if (!have_addr)
-		return;
-	lkp = (struct lock *)addr;
+	lkp = (struct lock *)lock;
 
 	db_printf("lock type: %s\n", lkp->lk_wmesg);
 	db_printf("state: ");

sys/kern/kern_mutex.c

@@ -656,7 +656,7 @@ mtx_init(struct mtx *m, const char *name, const char *type, int opts)
 	m->mtx_lock = MTX_UNOWNED;
 	m->mtx_recurse = 0;
 
-	lock_profile_object_init(&m->mtx_object, name);
+	lock_profile_object_init(&m->mtx_object, class, name);
 	lock_init(&m->mtx_object, class, name, type, flags);
 }
 

sys/kern/kern_rwlock.c

@@ -86,7 +86,7 @@ rw_init(struct rwlock *rw, const char *name)
 
 	rw->rw_lock = RW_UNLOCKED;
 
-	lock_profile_object_init(&rw->rw_object, name);
+	lock_profile_object_init(&rw->rw_object, &lock_class_rw, name);
 	lock_init(&rw->rw_object, &lock_class_rw, name, NULL, LO_WITNESS |
 	    LO_RECURSABLE | LO_UPGRADABLE);
 }

sys/kern/kern_sx.c

@@ -86,7 +86,7 @@ sx_init(struct sx *sx, const char *description)
 	cv_init(&sx->sx_excl_cv, description);
 	sx->sx_excl_wcnt = 0;
 	sx->sx_xholder = NULL;
-	lock_profile_object_init(&sx->sx_object, description);
+	lock_profile_object_init(&sx->sx_object, &lock_class_sx, description);
 	lock_init(&sx->sx_object, &lock_class_sx, description, NULL,
 	    LO_WITNESS | LO_RECURSABLE | LO_SLEEPABLE | LO_UPGRADABLE);
 }

sys/kern/subr_lock.c

@@ -58,6 +58,7 @@ struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = {
 	&lock_class_mtx_sleep,
 	&lock_class_sx,
 	&lock_class_rw,
+	&lock_class_lockmgr,
 };
 
 #ifdef LOCK_PROFILING
@@ -305,9 +306,9 @@ void _lock_profile_update_wait(struct lock_object *lo, uint64_t waitstart)
                         }
 			mpp->file = p;
 			mpp->line = l->lpo_lineno;
-			mpp->name = lo->lo_name;
-			mpp->type = lo->lo_type;
 			mpp->namehash = l->lpo_namehash;
+			mpp->type = l->lpo_type;
+			mpp->name = lo->lo_name;
 			if (collision)
 				++lock_prof_collisions;
                         /* We might have raced someone else but who cares, they'll try again next time */
@@ -368,7 +369,7 @@ void _lock_profile_release_lock(struct lock_object *lo)
 			mpp->file = p;
 			mpp->line = l->lpo_lineno;
 			mpp->namehash = l->lpo_namehash;
-			mpp->type = lo->lo_type;
+			mpp->type = l->lpo_type;
 			mpp->name = lo->lo_name;
 
 			if (collision)

sys/sys/_lock.h

@@ -36,11 +36,12 @@ struct lock_profile_object {
          * This does not result in variant structure sizes because
          * MUTEX_PROFILING is in opt_global.h
          */
-        u_int64_t               lpo_acqtime;
-        u_int64_t               lpo_waittime;
-        const char              *lpo_filename;
-        u_int                   lpo_namehash;
-        int                     lpo_lineno;
+	u_int64_t               lpo_acqtime;
+	u_int64_t               lpo_waittime;
+	const char              *lpo_filename;
+	u_int                   lpo_namehash;
+	int                     lpo_lineno;
+	const char              *lpo_type;
         /*
          * Fields relating to measuring contention on mutexes.
          * holding must be accessed atomically since it's

sys/sys/lock.h

@@ -213,6 +213,7 @@ extern struct lock_class lock_class_mtx_sleep;
 extern struct lock_class lock_class_mtx_spin;
 extern struct lock_class lock_class_sx;
 extern struct lock_class lock_class_rw;
+extern struct lock_class lock_class_lockmgr;
 
 extern struct lock_class *lock_classes[];
 

sys/sys/lock_profile.h

@@ -91,7 +91,7 @@ static inline void lock_profile_init(void)
         }
 }
 
-static inline void lock_profile_object_init(struct lock_object *lo, const char *name) {
+static inline void lock_profile_object_init(struct lock_object *lo, struct lock_class *class, const char *name) {
 	const char *p;
 	u_int hash = 0;
 	struct lock_profile_object *l = &lo->lo_profile_obj;
@@ -104,6 +104,7 @@ static inline void lock_profile_object_init(struct lock_object *lo, const char *
 	l->lpo_lineno = 0;
 	l->lpo_contest_holding = 0;
 	l->lpo_contest_locking = 0;
+	l->lpo_type = class->lc_name;
 
 	/* Hash the mutex name to an int so we don't have to strcmp() it repeatedly */
 	for (p = name; *p != '\0'; p++)
@@ -170,7 +171,7 @@ static inline void lock_profile_obtain_lock_failed(struct lock_object *lo, int *
 static inline void lock_profile_obtain_lock_success(struct lock_object *lo, uint64_t waittime,  
 						    const char *file, int line) {;}
 static inline void lock_profile_object_destroy(struct lock_object *lo) {;}
-static inline void lock_profile_object_init(struct lock_object *lo, const char *name) {;}
+static inline void lock_profile_object_init(struct lock_object *lo, struct lock_class *class, const char *name) {;}
 
 #endif  /* !LOCK_PROFILING */