Add mutex_enter_nested() which maps to mutex_lock_nested()

Also add support for the "name" parameter in mutex_init().  The name
allows for better diagnostics, namely in /proc/lock_stats when
lock debugging is enabled.  Nested mutexes are necessary to support
CONFIG_PROVE_LOCKING. ZoL can use mutex_enter_nested()'s "class" argument
to to convey the locking hierarchy.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes #439

diff --git a/include/sys/mutex.h b/include/sys/mutex.h
index 5e2b2508a9d8d675c18be6915e71669a50ed486d..6355782c0592e97d4f0c40c3f63d58328f2959bf 100644 (file)
--- a/include/sys/mutex.h
+++ b/include/sys/mutex.h
@@ -67,7 +67,7 @@ typedef struct {
            (type == MUTEX_ADAPTIVE) ||                         \
            (type == MUTEX_FSTRANS));                           \
                                                                \
-       __mutex_init(MUTEX(mp), #mp, &__key);                   \
+       __mutex_init(MUTEX(mp), (name) ? (#name) : (#mp), &__key); \
        spin_lock_init(&(mp)->m_lock);                          \
        (mp)->m_type = type;                                    \
        (mp)->m_owner = NULL;                                   \
@@ -95,7 +95,19 @@ typedef struct {
        _rc_;                                                   \
 })
 
-#define        mutex_enter(mp)                                         \
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define        mutex_enter_nested(mp, subclass)                        \
+{                                                              \
+       ASSERT3P(mutex_owner(mp), !=, current);                 \
+       mutex_lock_nested(MUTEX(mp), (subclass));               \
+       (mp)->m_owner = current;                                \
+       if ((mp)->m_type == MUTEX_FSTRANS) {                    \
+               (mp)->m_saved_flags = current->flags;           \
+               current->flags |= PF_FSTRANS;                   \
+       }                                                       \
+}
+#else /* CONFIG_DEBUG_LOCK_ALLOC */
+#define        mutex_enter_nested(mp, subclass)                        \
 {                                                              \
        ASSERT3P(mutex_owner(mp), !=, current);                 \
        mutex_lock(MUTEX(mp));                                  \
@@ -105,6 +117,9 @@ typedef struct {
                current->flags |= PF_FSTRANS;                   \
        }                                                       \
 }
+#endif /*  CONFIG_DEBUG_LOCK_ALLOC */
+
+#define        mutex_enter(mp) mutex_enter_nested((mp), 0)
 
 /*
  * The reason for the spinlock: