From bcc894b69d0d9a1a6f14ad7bd613808cc9f22ef7 Mon Sep 17 00:00:00 2001
From: Richard Braun <rbraun@sceen.net>
Date: Sun, 11 Dec 2016 16:11:42 +0100
Subject: VM: make vm_wire more POSIX-friendly

* doc/mach.texi: Update return codes.
* vm/vm_map.c (vm_map_pageable_common): Return KERN_NO_SPACE instead
of KERN_FAILURE if some of the specified address range does not
correspond to mapped pages. Skip unwired entries instead of failing
when unwiring.
---
 doc/mach.texi |  6 ++----
 vm/vm_map.c   | 25 +++++++++++++++----------
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/doc/mach.texi b/doc/mach.texi
index 99ee8548..d2b88d1f 100644
--- a/doc/mach.texi
+++ b/doc/mach.texi
@@ -3261,10 +3261,8 @@ The function returns @code{KERN_SUCCESS} if the call succeeded,
 @code{KERN_INVALID_HOST} if @var{host} was not a valid host
 port, @code{KERN_INVALID_TASK} if @var{task} was not a valid task,
 @code{KERN_INVALID_VALUE} if @var{access} specified an invalid access
-mode, @code{KERN_FAILURE} if some memory in the specified range is not
-present or has an inappropriate protection value, and
-@code{KERN_INVALID_ARGUMENT} if unwiring (@var{access} is
-@code{VM_PROT_NONE}) and the memory is not already wired.
+mode, and @code{KERN_NO_SPACE} if some memory in the specified range
+is not present or has an inappropriate protection value.
 
 The @code{vm_wire} call is actually an RPC to @var{host}, normally
 a send right for a privileged host port, but potentially any send right.
diff --git a/vm/vm_map.c b/vm/vm_map.c
index 003694dd..7db9ceda 100644
--- a/vm/vm_map.c
+++ b/vm/vm_map.c
@@ -1477,7 +1477,7 @@ kern_return_t vm_map_pageable_common(
 		 *	Start address is not in map; this is fatal.
 		 */
 		vm_map_unlock(map);
-		return(KERN_FAILURE);
+		return(KERN_NO_SPACE);
 	}
 
 	/*
@@ -1490,19 +1490,17 @@ kern_return_t vm_map_pageable_common(
 		vm_map_clip_start(map, entry, start);
 
 		/*
-		 *	Unwiring.  First ensure that the range to be
-		 *	unwired is really wired down.
+		 *	Unwiring.  First ensure that there are no holes
+		 *	in the specified range.
 		 */
 		while ((entry != vm_map_to_entry(map)) &&
 		       (entry->vme_start < end)) {
 
-		    if ((entry->wired_count == 0) ||
-		    	((entry->vme_end < end) &&
-			 ((entry->vme_next == vm_map_to_entry(map)) ||
-			  (entry->vme_next->vme_start > entry->vme_end))) ||
-			(user_wire && (entry->user_wired_count == 0))) {
+		    if ((entry->vme_end < end) &&
+			((entry->vme_next == vm_map_to_entry(map)) ||
+			 (entry->vme_next->vme_start > entry->vme_end))) {
 			    vm_map_unlock(map);
-			    return(KERN_INVALID_ARGUMENT);
+			    return(KERN_NO_SPACE);
 		    }
 		    entry = entry->vme_next;
 		}
@@ -1517,6 +1515,13 @@ kern_return_t vm_map_pageable_common(
 		       (entry->vme_start < end)) {
 		    vm_map_clip_end(map, entry, end);
 
+		    /* Skip unwired entries */
+		    if (entry->wired_count == 0) {
+			assert(entry->user_wired_count == 0);
+			entry = entry->vme_next;
+			continue;
+		    }
+
 		    if (user_wire) {
 			if (--(entry->user_wired_count) == 0)
 			{
@@ -1641,7 +1646,7 @@ kern_return_t vm_map_pageable_common(
 			    }
 
 			    vm_map_unlock(map);
-			    return(KERN_FAILURE);
+			    return(KERN_NO_SPACE);
 		    }
 		    entry = entry->vme_next;
 		}
-- 
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