Clean up the root mount and mount wait code. No mutexes are needed here

since a spurious wakeup() is the only possible outcome and this is fine in
the BSD programming model.

1 files changed, 10 insertions, 15 deletions

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
index b7dec78..c6ddedb 100644
--- a/sys/kern/vfs_mount.c
+++ b/sys/kern/vfs_mount.c
@@ -1312,7 +1312,7 @@ struct root_hold_token {
 static LIST_HEAD(, root_hold_token)	root_holds =
     LIST_HEAD_INITIALIZER(&root_holds);
 
-static int root_mount_complete = 0;
+static int root_mount_complete;
 
 /*
  * Hold root mount.
@@ -1377,24 +1377,23 @@ static void
 root_mount_done(void)
 {
 
-	mtx_lock(&mountlist_mtx);
+	/*
+	 * No mutex is acquired here because int stores are atomic.  If a
+	 * thread is polling root_mount_complete, it may get a spurious
+	 * wakeup() but that is fine in the tsleep()/wakeup() model.
+	 */
 	root_mount_complete = 1;
 	wakeup(&root_mount_complete);
-	mtx_unlock(&mountlist_mtx);
 }
 
- /*
+/*
  * Return true if root is already mounted.
  */
 int
 root_mounted(void)
 {
-	int mounted;
 
-	mtx_lock(&mountlist_mtx);
-	mounted = root_mount_complete;
-	mtx_unlock(&mountlist_mtx);
-	return (mounted);
+	return (root_mount_complete);
 }
 
 /*
@@ -1410,12 +1409,8 @@ root_mount_wait(void)
 	 */
 	KASSERT(curthread->td_proc->p_pid != 0,
 	    ("root_mount_wait: cannot be called from the swapper thread"));
-	mtx_lock(&mountlist_mtx);
-	while (!root_mount_complete) {
-		msleep(&root_mount_complete, &mountlist_mtx, PZERO, "rootwait",
-		    hz);
-	}
-	mtx_unlock(&mountlist_mtx);
+	while (!root_mount_complete)
+		tsleep(&root_mount_complete, PZERO, "rootwait", hz);
 }
 
 static void