gsync: Fix assertion failure with MACH_LDEBUG

vm_map_lock_read calls check_simple_locks(), so we need to lock hbp
after taking the vm_map read lock.

* kern/gsync.c (gsync_wait): Call vm_map_lock_read before locking
&hbp->lock.
(gsync_wake): Likewise.

1 files changed, 5 insertions, 5 deletions

diff --git a/kern/gsync.c b/kern/gsync.c
index 68b3d0b0..d0f609fb 100644
--- a/kern/gsync.c
+++ b/kern/gsync.c
@@ -191,14 +191,14 @@ kern_return_t gsync_wait (task_t task, vm_offset_t addr,
   if (unlikely (bucket < 0))
     return (KERN_INVALID_ADDRESS);
 
-  struct gsync_hbucket *hbp = gsync_buckets + bucket;
-  simple_lock (&hbp->lock);
-
-  /* Now test that the address is actually valid for the
+  /* Test that the address is actually valid for the
    * given task. Do so with the read-lock held in order
    * to prevent memory deallocations. */
   vm_map_lock_read (task->map);
 
+  struct gsync_hbucket *hbp = gsync_buckets + bucket;
+  simple_lock (&hbp->lock);
+
   if (unlikely (!valid_access_p (task->map, addr, flags)))
     {
       simple_unlock (&hbp->lock);
@@ -285,9 +285,9 @@ kern_return_t gsync_wake (task_t task,
 
   kern_return_t ret = KERN_INVALID_ARGUMENT;
 
+  vm_map_lock_read (task->map);
   struct gsync_hbucket *hbp = gsync_buckets + bucket;
   simple_lock (&hbp->lock);
-  vm_map_lock_read (task->map);
 
   if (unlikely (!valid_access_p (task->map, addr, flags)))
     {