OS-7753 THREAD_KPRI_RELEASE does nothing of the sort
Reviewed by: Bryan Cantrill <bryan@joyent.com>
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>

@@ -19,10 +19,11 @@
  * CDDL HEADER END
  */
 
 /*
  * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #include <sys/param.h>
 #include <sys/vmparam.h>
 #include <sys/types.h>

@@ -1024,11 +1025,10 @@
 
         /*
          * Try to autoload the system call if necessary.
          */
         module_lock = lock_syscall(se, code);
-        THREAD_KPRI_RELEASE();  /* drop priority given by rw_enter */
 
         /*
          * we've locked either the loaded syscall or nosys
          */
         if (callp->sy_flags & SE_ARGC) {

@@ -1038,11 +1038,10 @@
                 rval = (*sy_call)(a0, a1, a2, a3, a4, a5);
         } else {
                 rval = syscall_ap();
         }
 
-        THREAD_KPRI_REQUEST();  /* regain priority from read lock */
         rw_exit(module_lock);
         return (rval);
 }
 
 /*