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>

@@ -18,10 +18,11 @@
  *
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 
 /*
  * VM - page locking primitives

@@ -362,11 +363,10 @@
                          * writer that wants exclusive access, return failure
                          */
                         retval = 0;
                 } else if ((pp->p_selock & ~SE_EWANTED) == 0) {
                         /* no reader/writer lock held */
-                        THREAD_KPRI_REQUEST();
                         /* this clears our setting of the SE_EWANTED bit */
                         pp->p_selock = SE_WRITER;
                         retval = 1;
                 } else {
                         /* page is locked */

@@ -549,11 +549,10 @@
          * SE_EXCL_WANTED.
          */
         if (!(old & SE_EWANTED) || (es & SE_EXCL_WANTED)) {
                 if ((old & ~SE_EWANTED) == 0) {
                         /* no reader/writer lock held */
-                        THREAD_KPRI_REQUEST();
                         /* this clears out our setting of the SE_EWANTED bit */
                         pp->p_selock = SE_WRITER;
                         mutex_exit(pse);
                         return (1);
                 }

@@ -588,11 +587,10 @@
                 return (0);
         }
 
         if (se == SE_EXCL) {
                 if (pp->p_selock == 0) {
-                        THREAD_KPRI_REQUEST();
                         pp->p_selock = SE_WRITER;
                         mutex_exit(pse);
                         return (1);
                 }
         } else {

@@ -626,11 +624,10 @@
                 if (CV_HAS_WAITERS(&pp->p_cv))
                         cv_broadcast(&pp->p_cv);
         } else if ((old & ~SE_EWANTED) == SE_DELETED) {
                 panic("page_unlock_nocapture: page %p is deleted", (void *)pp);
         } else if (old < 0) {
-                THREAD_KPRI_RELEASE();
                 pp->p_selock &= SE_EWANTED;
                 if (CV_HAS_WAITERS(&pp->p_cv))
                         cv_broadcast(&pp->p_cv);
         } else if ((old & ~SE_EWANTED) > SE_READER) {
                 pp->p_selock = old - SE_READER;

@@ -660,11 +657,10 @@
                 if (CV_HAS_WAITERS(&pp->p_cv))
                         cv_broadcast(&pp->p_cv);
         } else if ((old & ~SE_EWANTED) == SE_DELETED) {
                 panic("page_unlock: page %p is deleted", (void *)pp);
         } else if (old < 0) {
-                THREAD_KPRI_RELEASE();
                 pp->p_selock &= SE_EWANTED;
                 if (CV_HAS_WAITERS(&pp->p_cv))
                         cv_broadcast(&pp->p_cv);
         } else if ((old & ~SE_EWANTED) > SE_READER) {
                 pp->p_selock = old - SE_READER;

@@ -680,11 +676,10 @@
                  * relatively long time in the kernel making no progress.
                  */
                 if ((pp->p_toxic & PR_CAPTURE) &&
                     !(curthread->t_flag & T_CAPTURING) &&
                     !PP_RETIRED(pp)) {
-                        THREAD_KPRI_REQUEST();
                         pp->p_selock = SE_WRITER;
                         mutex_exit(pse);
                         page_unlock_capture(pp);
                 } else {
                         mutex_exit(pse);

@@ -710,11 +705,10 @@
 
         mutex_enter(pse);
         if (!(pp->p_selock & SE_EWANTED)) {
                 /* no threads want exclusive access, try upgrade */
                 if (pp->p_selock == SE_READER) {
-                        THREAD_KPRI_REQUEST();
                         /* convert to exclusive lock */
                         pp->p_selock = SE_WRITER;
                         mutex_exit(pse);
                         return (1);
                 }

@@ -736,11 +730,10 @@
         ASSERT((pp->p_selock & ~SE_EWANTED) != SE_DELETED);
         ASSERT(PAGE_EXCL(pp));
 
         mutex_enter(pse);
         excl_waiting =  pp->p_selock & SE_EWANTED;
-        THREAD_KPRI_RELEASE();
         pp->p_selock = SE_READER | excl_waiting;
         if (CV_HAS_WAITERS(&pp->p_cv))
                 cv_broadcast(&pp->p_cv);
         mutex_exit(pse);
 }

@@ -754,11 +747,10 @@
         ASSERT(pp->p_vnode == NULL);
         ASSERT(pp->p_offset == (u_offset_t)-1);
         ASSERT(!PP_ISFREE(pp));
 
         mutex_enter(pse);
-        THREAD_KPRI_RELEASE();
         pp->p_selock = SE_DELETED;
         if (CV_HAS_WAITERS(&pp->p_cv))
                 cv_broadcast(&pp->p_cv);
         mutex_exit(pse);
 }