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vm_pager_object_lookup: small performance optimization

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do not needlessly lock an object if its handle doesn't match

Reviewed by:	kib, alc
MFC after:	1 week
This commit is contained in:
Andriy Gapon 2012-05-23 12:51:49 +00:00
parent 807aad636f
commit b6062382be
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=235829
1 changed files with 7 additions and 6 deletions
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13
sys/vm/vm_pager.c
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@ -271,14 +271,15 @@ vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
vm_object_t object;
TAILQ_FOREACH(object, pg_list, pager_object_list) {
VM_OBJECT_LOCK(object);
if (object->handle == handle &&
(object->flags & OBJ_DEAD) == 0) {
vm_object_reference_locked(object);
if (object->handle == handle) {
VM_OBJECT_LOCK(object);
if ((object->flags & OBJ_DEAD) == 0) {
vm_object_reference_locked(object);
VM_OBJECT_UNLOCK(object);
break;
}
VM_OBJECT_UNLOCK(object);
break;
}
VM_OBJECT_UNLOCK(object);
}
return (object);
}