Rename tsleep to msleep and add a mutex argument, which is

released before sleeping and re-acquired before msleep
returns.  A compatibility cpp macro has been provided for
tsleep to avoid changing all occurences of it in the kernel.

Remove an assertion that the Giant mutex be held before
calling tsleep or asleep.

This is intended to serve the same purpose as condition
variables, but does not preclude their addition in the
future.

Approved by:	jasone
Obtained from:	BSD/OS

1 files changed, 19 insertions, 4 deletions

diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index 6c53f8f..cd41140 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -408,10 +408,15 @@ sleepinit(void)
  * signal needs to be delivered, ERESTART is returned if the current system
  * call should be restarted if possible, and EINTR is returned if the system
  * call should be interrupted by the signal (return EINTR).
+ *
+ * The mutex argument is exited before the caller is suspended, and
+ * entered before msleep returns.  If priority includes the PDROP
+ * flag the mutex is not entered before returning.
  */
 int
-tsleep(ident, priority, wmesg, timo)
+msleep(ident, mtx, priority, wmesg, timo)
 	void *ident;
+	mtx_t *mtx;
 	int priority, timo;
 	const char *wmesg;
 {
@@ -419,14 +424,22 @@ tsleep(ident, priority, wmesg, timo)
 	int s, sig, catch = priority & PCATCH;
 	struct callout_handle thandle;
 	int rval = 0;
+	WITNESS_SAVE_DECL(mtx);
 
 #ifdef KTRACE
 	if (p && KTRPOINT(p, KTR_CSW))
 		ktrcsw(p->p_tracep, 1, 0);
 #endif
-	mtx_assert(&Giant, MA_OWNED);
+	WITNESS_SLEEP(0, mtx);
 	mtx_enter(&sched_lock, MTX_SPIN);
 
+	if (mtx != NULL) {
+		WITNESS_SAVE(mtx, mtx);
+		mtx_exit(mtx, MTX_DEF | MTX_NOSWITCH);
+		if (priority & PDROP)
+			mtx = NULL;
+	}
+
 	s = splhigh();
 	if (cold || panicstr) {
 		/*
@@ -527,7 +540,10 @@ out:
 	if (KTRPOINT(p, KTR_CSW))
 		ktrcsw(p->p_tracep, 0, 0);
 #endif
-
+	if (mtx != NULL) {
+		mtx_enter(mtx, MTX_DEF);
+		WITNESS_RESTORE(mtx, mtx);
+	}
 	return (rval);
 }
 
@@ -600,7 +616,6 @@ await(int priority, int timo)
 	int rval = 0;
 	int s;
 
-	mtx_assert(&Giant, MA_OWNED);
 	mtx_enter(&sched_lock, MTX_SPIN);
 
 	s = splhigh();