Add two new function pointers 'lc_lock' and 'lc_unlock' to lock classes.

These functions are intended to be used to drop a lock and then reacquire
it when doing an sleep such as msleep(9).  Both functions accept a
'struct lock_object *' as their first parameter.  The 'lc_unlock' function
returns an integer that is then passed as the second paramter to the
subsequent 'lc_lock' function.  This can be used to communicate state.
For example, sx locks and rwlocks use this to indicate if the lock was
share/read locked vs exclusive/write locked.

Currently, spin mutexes and lockmgr locks do not provide working lc_lock
and lc_unlock functions.

1 files changed, 40 insertions, 0 deletions

diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c
index 0fd5d7e..b327ef8 100644
--- a/sys/kern/kern_mutex.c
+++ b/sys/kern/kern_mutex.c
@@ -91,6 +91,10 @@ __FBSDID("$FreeBSD$");
 #ifdef DDB
 static void	db_show_mtx(struct lock_object *lock);
 #endif
+static void	lock_mtx(struct lock_object *lock, int how);
+static void	lock_spin(struct lock_object *lock, int how);
+static int	unlock_mtx(struct lock_object *lock);
+static int	unlock_spin(struct lock_object *lock);
 
 /*
  * Lock classes for sleep and spin mutexes.
@@ -101,6 +105,8 @@ struct lock_class lock_class_mtx_sleep = {
 #ifdef DDB
 	.lc_ddb_show = db_show_mtx,
 #endif
+	.lc_lock = lock_mtx,
+	.lc_unlock = unlock_mtx,
 };
 struct lock_class lock_class_mtx_spin = {
 	.lc_name = "spin mutex",
@@ -108,6 +114,8 @@ struct lock_class lock_class_mtx_spin = {
 #ifdef DDB
 	.lc_ddb_show = db_show_mtx,
 #endif
+	.lc_lock = lock_spin,
+	.lc_unlock = unlock_spin,
 };
 
 /*
@@ -130,6 +138,38 @@ static inline void lock_profile_init(void)
 static inline void lock_profile_init(void) {;}
 #endif
 
+void
+lock_mtx(struct lock_object *lock, int how)
+{
+
+	mtx_lock((struct mtx *)lock);
+}
+
+void
+lock_spin(struct lock_object *lock, int how)
+{
+
+	panic("spin locks can only use msleep_spin");
+}
+
+int
+unlock_mtx(struct lock_object *lock)
+{
+	struct mtx *m;
+
+	m = (struct mtx *)lock;
+	mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
+	mtx_unlock(m);
+	return (0);
+}
+
+int
+unlock_spin(struct lock_object *lock)
+{
+
+	panic("spin locks can only use msleep_spin");
+}
+
 /*
  * Function versions of the inlined __mtx_* macros.  These are used by
  * modules and can also be called from assembly language if needed.