svn commit: r286277 - head/sys/kern

[Ed Schouten]

Author: ed
Date: Tue Aug  4 06:01:13 2015
New Revision: 286277
URL: https://svnweb.freebsd.org/changeset/base/286277

Log:
  Fix bad arithmetic in umtx_key_get() to compute object offset.
  
  It looks like umtx_key_get() has the addition and subtraction the wrong
  way around, meaning that it fails to match in certain cases. This causes
  the cloudlibc unit tests to deadlock in certain cases.
  
  Reviewed by:	kib
  Differential Revision:	https://reviews.freebsd.org/D3287

Modified:
  head/sys/kern/kern_umtx.c

Modified: head/sys/kern/kern_umtx.c
==============================================================================
--- head/sys/kern/kern_umtx.c	Tue Aug  4 05:18:24 2015	(r286276)
+++ head/sys/kern/kern_umtx.c	Tue Aug  4 06:01:13 2015	(r286277)
@@ -820,8 +820,8 @@ umtx_key_get(const void *addr, int type,
 		    (share == AUTO_SHARE &&
 		     VM_INHERIT_SHARE == entry->inheritance)) {
 			key->shared = 1;
-			key->info.shared.offset = entry->offset + entry->start -
-				(vm_offset_t)addr;
+			key->info.shared.offset = (vm_offset_t)addr -
+			    entry->start + entry->offset;
 			vm_object_reference(key->info.shared.object);
 		} else {
 			key->shared = 0;