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- Simplify vm_object_collapse()'s collapse case, reducing the number

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of lock acquires and releases performed.
 - Move an assertion from vm_object_collapse() to vm_object_zdtor()
   because it applies to all cases of object destruction.
This commit is contained in:
Alan Cox 2003-10-26 06:29:26 +00:00
parent 87931aff11
commit 43186e53ae
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=121562
1 changed files with 9 additions and 14 deletions
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23
sys/vm/vm_object.c
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@ -160,6 +160,9 @@ vm_object_zdtor(void *mem, int size, void *arg)
vm_object_t object;
object = (vm_object_t)mem;
KASSERT(TAILQ_EMPTY(&object->memq),
("object %p has resident pages",
object));
KASSERT(object->paging_in_progress == 0,
("object %p paging_in_progress = %d",
object, object->paging_in_progress));
@ -1585,23 +1588,16 @@ vm_object_collapse(vm_object_t object)
if (backing_object->backing_object) {
VM_OBJECT_LOCK(backing_object->backing_object);
LIST_REMOVE(backing_object, shadow_list);
backing_object->backing_object->shadow_count--;
LIST_INSERT_HEAD(
&backing_object->backing_object->shadow_head,
object, shadow_list);
/*
* The shadow_count has not changed.
*/
backing_object->backing_object->generation++;
VM_OBJECT_UNLOCK(backing_object->backing_object);
}
object->backing_object = backing_object->backing_object;
if (object->backing_object) {
VM_OBJECT_LOCK(object->backing_object);
LIST_INSERT_HEAD(
&object->backing_object->shadow_head,
object,
shadow_list
);
object->backing_object->shadow_count++;
object->backing_object->generation++;
VM_OBJECT_UNLOCK(object->backing_object);
}
object->backing_object_offset +=
backing_object->backing_object_offset;
/* XXX */ VM_OBJECT_UNLOCK(object);
@ -1614,7 +1610,6 @@ vm_object_collapse(vm_object_t object)
* necessary is to dispose of it.
*/
KASSERT(backing_object->ref_count == 1, ("backing_object %p was somehow re-referenced during collapse!", backing_object));
KASSERT(TAILQ_FIRST(&backing_object->memq) == NULL, ("backing_object %p somehow has left over pages during collapse!", backing_object));
VM_OBJECT_UNLOCK(backing_object);
mtx_lock(&vm_object_list_mtx);