Split the WITNESS and MUTEX_DEBUG options apart so that WITNESS does not

depend on MUTEX_DEBUG.  The MUTEX_DEBUG option turns on extra assertions
and checks to verify that mutexes themselves are implemented properly.
The WITNESS option uses extra checks and diagnostics to verify that other
code is using mutexes properly.

4 files changed, 42 insertions, 36 deletions

diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c
index 14d4ce5..5290d90 100644
--- a/sys/kern/kern_mutex.c
+++ b/sys/kern/kern_mutex.c
@@ -85,17 +85,17 @@
  * Machine independent bits of the mutex implementation
  */
 /* All mutexes in system (used for debug/panic) */
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0,
 	"All mutexes queue head" };
 static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, &all_mtx_debug,
 	TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
 	{ NULL, NULL }, &all_mtx, &all_mtx };
-#else	/* MUTEX_DEBUG */
+#else	/* WITNESS */
 static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, "All mutexes queue head",
 	TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
 	{ NULL, NULL }, &all_mtx, &all_mtx };
-#endif	/* MUTEX_DEBUG */
+#endif	/* WITNESS */
 
 static int	mtx_cur_cnt;
 static int	mtx_max_cnt;
@@ -578,7 +578,7 @@ mtx_validate(struct mtx *m, int when)
 void
 mtx_init(struct mtx *m, const char *t, int flag)
 {
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	struct mtx_debug *debug;
 #endif
 
@@ -586,6 +586,8 @@ mtx_init(struct mtx *m, const char *t, int flag)
 #ifdef MUTEX_DEBUG
 	if (mtx_validate(m, MV_INIT))	/* diagnostic and error correction */
 		return;
+#endif
+#ifdef WITNESS
 	if (flag & MTX_COLD)
 		debug = m->mtx_debug;
 	else
@@ -604,7 +606,7 @@ mtx_init(struct mtx *m, const char *t, int flag)
 #endif
 	bzero((void *)m, sizeof *m);
 	TAILQ_INIT(&m->mtx_blocked);
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	m->mtx_debug = debug;
 #endif
 	m->mtx_description = t;
@@ -650,6 +652,8 @@ mtx_destroy(struct mtx *m)
 	m->mtx_prev->mtx_next = m->mtx_next;
 #ifdef MUTEX_DEBUG
 	m->mtx_next = m->mtx_prev = NULL;
+#endif
+#ifdef WITNESS
 	free(m->mtx_debug, M_DEVBUF);
 	m->mtx_debug = NULL;
 #endif
@@ -659,10 +663,9 @@ mtx_destroy(struct mtx *m)
 
 /*
  * The non-inlined versions of the mtx_*() functions are always built (above),
- * but the witness code depends on the MUTEX_DEBUG and WITNESS kernel options
- * being specified.
+ * but the witness code depends on the WITNESS kernel option being specified.
  */
-#if (defined(MUTEX_DEBUG) && defined(WITNESS))
+#ifdef WITNESS
 
 #define WITNESS_COUNT 200
 #define	WITNESS_NCHILDREN 2
@@ -1377,4 +1380,4 @@ witness_restore(struct mtx *m, const char *file, int line)
 	m->mtx_witness->w_line = line;
 }
 
-#endif	/* (defined(MUTEX_DEBUG) && defined(WITNESS)) */
+#endif	/* WITNESS */
diff --git a/sys/kern/subr_turnstile.c b/sys/kern/subr_turnstile.c
index 14d4ce5..5290d90 100644
--- a/sys/kern/subr_turnstile.c
+++ b/sys/kern/subr_turnstile.c
@@ -85,17 +85,17 @@
  * Machine independent bits of the mutex implementation
  */
 /* All mutexes in system (used for debug/panic) */
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0,
 	"All mutexes queue head" };
 static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, &all_mtx_debug,
 	TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
 	{ NULL, NULL }, &all_mtx, &all_mtx };
-#else	/* MUTEX_DEBUG */
+#else	/* WITNESS */
 static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, "All mutexes queue head",
 	TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
 	{ NULL, NULL }, &all_mtx, &all_mtx };
-#endif	/* MUTEX_DEBUG */
+#endif	/* WITNESS */
 
 static int	mtx_cur_cnt;
 static int	mtx_max_cnt;
@@ -578,7 +578,7 @@ mtx_validate(struct mtx *m, int when)
 void
 mtx_init(struct mtx *m, const char *t, int flag)
 {
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	struct mtx_debug *debug;
 #endif
 
@@ -586,6 +586,8 @@ mtx_init(struct mtx *m, const char *t, int flag)
 #ifdef MUTEX_DEBUG
 	if (mtx_validate(m, MV_INIT))	/* diagnostic and error correction */
 		return;
+#endif
+#ifdef WITNESS
 	if (flag & MTX_COLD)
 		debug = m->mtx_debug;
 	else
@@ -604,7 +606,7 @@ mtx_init(struct mtx *m, const char *t, int flag)
 #endif
 	bzero((void *)m, sizeof *m);
 	TAILQ_INIT(&m->mtx_blocked);
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	m->mtx_debug = debug;
 #endif
 	m->mtx_description = t;
@@ -650,6 +652,8 @@ mtx_destroy(struct mtx *m)
 	m->mtx_prev->mtx_next = m->mtx_next;
 #ifdef MUTEX_DEBUG
 	m->mtx_next = m->mtx_prev = NULL;
+#endif
+#ifdef WITNESS
 	free(m->mtx_debug, M_DEVBUF);
 	m->mtx_debug = NULL;
 #endif
@@ -659,10 +663,9 @@ mtx_destroy(struct mtx *m)
 
 /*
  * The non-inlined versions of the mtx_*() functions are always built (above),
- * but the witness code depends on the MUTEX_DEBUG and WITNESS kernel options
- * being specified.
+ * but the witness code depends on the WITNESS kernel option being specified.
  */
-#if (defined(MUTEX_DEBUG) && defined(WITNESS))
+#ifdef WITNESS
 
 #define WITNESS_COUNT 200
 #define	WITNESS_NCHILDREN 2
@@ -1377,4 +1380,4 @@ witness_restore(struct mtx *m, const char *file, int line)
 	m->mtx_witness->w_line = line;
 }
 
-#endif	/* (defined(MUTEX_DEBUG) && defined(WITNESS)) */
+#endif	/* WITNESS */
diff --git a/sys/kern/subr_witness.c b/sys/kern/subr_witness.c
index 14d4ce5..5290d90 100644
--- a/sys/kern/subr_witness.c
+++ b/sys/kern/subr_witness.c
@@ -85,17 +85,17 @@
  * Machine independent bits of the mutex implementation
  */
 /* All mutexes in system (used for debug/panic) */
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0,
 	"All mutexes queue head" };
 static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, &all_mtx_debug,
 	TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
 	{ NULL, NULL }, &all_mtx, &all_mtx };
-#else	/* MUTEX_DEBUG */
+#else	/* WITNESS */
 static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, "All mutexes queue head",
 	TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked),
 	{ NULL, NULL }, &all_mtx, &all_mtx };
-#endif	/* MUTEX_DEBUG */
+#endif	/* WITNESS */
 
 static int	mtx_cur_cnt;
 static int	mtx_max_cnt;
@@ -578,7 +578,7 @@ mtx_validate(struct mtx *m, int when)
 void
 mtx_init(struct mtx *m, const char *t, int flag)
 {
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	struct mtx_debug *debug;
 #endif
 
@@ -586,6 +586,8 @@ mtx_init(struct mtx *m, const char *t, int flag)
 #ifdef MUTEX_DEBUG
 	if (mtx_validate(m, MV_INIT))	/* diagnostic and error correction */
 		return;
+#endif
+#ifdef WITNESS
 	if (flag & MTX_COLD)
 		debug = m->mtx_debug;
 	else
@@ -604,7 +606,7 @@ mtx_init(struct mtx *m, const char *t, int flag)
 #endif
 	bzero((void *)m, sizeof *m);
 	TAILQ_INIT(&m->mtx_blocked);
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	m->mtx_debug = debug;
 #endif
 	m->mtx_description = t;
@@ -650,6 +652,8 @@ mtx_destroy(struct mtx *m)
 	m->mtx_prev->mtx_next = m->mtx_next;
 #ifdef MUTEX_DEBUG
 	m->mtx_next = m->mtx_prev = NULL;
+#endif
+#ifdef WITNESS
 	free(m->mtx_debug, M_DEVBUF);
 	m->mtx_debug = NULL;
 #endif
@@ -659,10 +663,9 @@ mtx_destroy(struct mtx *m)
 
 /*
  * The non-inlined versions of the mtx_*() functions are always built (above),
- * but the witness code depends on the MUTEX_DEBUG and WITNESS kernel options
- * being specified.
+ * but the witness code depends on the WITNESS kernel option being specified.
  */
-#if (defined(MUTEX_DEBUG) && defined(WITNESS))
+#ifdef WITNESS
 
 #define WITNESS_COUNT 200
 #define	WITNESS_NCHILDREN 2
@@ -1377,4 +1380,4 @@ witness_restore(struct mtx *m, const char *file, int line)
 	m->mtx_witness->w_line = line;
 }
 
-#endif	/* (defined(MUTEX_DEBUG) && defined(WITNESS)) */
+#endif	/* WITNESS */
diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h
index 53bc878..3532e99 100644
--- a/sys/sys/mutex.h
+++ b/sys/sys/mutex.h
@@ -86,7 +86,7 @@
 
 #endif	/* _KERNEL */
 
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 struct mtx_debug {
 	/* If you add anything here, adjust the mtxf_t definition below */
 	struct witness	*mtxd_witness;
@@ -101,7 +101,7 @@ struct mtx_debug {
 #define	mtx_line	mtx_debug->mtxd_line
 #define	mtx_file	mtx_debug->mtxd_file
 #define	mtx_witness	mtx_debug->mtxd_witness
-#endif
+#endif	/* WITNESS */
 
 /*
  * Sleep/spin mutex
@@ -110,7 +110,7 @@ struct mtx {
 	volatile uintptr_t mtx_lock;	/* lock owner/gate/flags */
 	volatile u_int	mtx_recurse;	/* number of recursive holds */
 	u_int		mtx_saveintr;	/* saved flags (for spin locks) */
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	struct mtx_debug *mtx_debug;
 #else
 	const char	*mtx_description;
@@ -121,7 +121,7 @@ struct mtx {
 	struct mtx	*mtx_prev;
 };
 
-#ifdef	MUTEX_DEBUG
+#ifdef	WITNESS
 #define	MUTEX_DECLARE(modifiers, name)					\
 	static struct mtx_debug __mtx_debug_##name;			\
 	modifiers struct mtx name = { 0, 0, 0, &__mtx_debug_##name }
@@ -262,9 +262,6 @@ do {									\
 #endif	/* MUTEX_DEBUG */
 
 #ifdef	WITNESS
-#ifndef	MUTEX_DEBUG
-#error	WITNESS requires MUTEX_DEBUG
-#endif	/* MUTEX_DEBUG */
 #define WITNESS_ENTER(m, t, f, l)					\
 	if ((m)->mtx_witness != NULL)					\
 		witness_enter((m), (t), (f), (l))
@@ -550,12 +547,12 @@ _mtx_try_enter(struct mtx *mtxp, int type, const char *file, int line)
 	int	rval;
 
 	rval = _obtain_lock(mpp, CURTHD);
-#ifdef MUTEX_DEBUG
+#ifdef WITNESS
 	if (rval && mpp->mtx_witness != NULL) {
 		MPASS(mpp->mtx_recurse == 0);
 		witness_try_enter(mpp, type, file, line);
 	}
-#endif
+#endif	/* WITNESS */
 	CTR5(KTR_LOCK, STR_mtx_try_enter_fmt,
 	    mpp->mtx_description, mpp, rval, file, line);