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- Introduce and use vm_object_reference_locked(). Unlike

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vm_object_reference(), this function must not be used to reanimate dead
   vm objects.  This restriction simplifies locking.

Reviewed by:	tegge
This commit is contained in:
Alan Cox 2003-11-02 21:30:10 +00:00
parent 8b99b80de6
commit b921a12b3b
3 changed files with 26 additions and 3 deletions
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2
sys/vm/vm_map.c
View File

@ -2369,8 +2369,8 @@ vm_map_copy_entry(
}
}
vm_object_reference(src_object);
VM_OBJECT_LOCK(src_object);
vm_object_reference_locked(src_object);
vm_object_clear_flag(src_object, OBJ_ONEMAPPING);
VM_OBJECT_UNLOCK(src_object);
dst_entry->object.vm_object = src_object;

26
sys/vm/vm_object.c
View File

@ -376,6 +376,28 @@ vm_object_reference(vm_object_t object)
VM_OBJECT_UNLOCK(object);
}
/*
* vm_object_reference_locked:
*
* Gets another reference to the given object.
*
* The object must be locked.
*/
void
vm_object_reference_locked(vm_object_t object)
{
struct vnode *vp;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
KASSERT((object->flags & OBJ_DEAD) == 0,
("vm_object_reference_locked: dead object referenced"));
object->ref_count++;
if (object->type == OBJT_VNODE) {
vp = object->handle;
vref(vp);
}
}
/*
* Handle deallocating an object of type OBJT_VNODE.
*/
@ -1184,12 +1206,12 @@ vm_object_split(vm_map_entry_t entry)
source = orig_object->backing_object;
if (source != NULL) {
vm_object_reference(source); /* Referenced by new_object */
VM_OBJECT_LOCK(source);
LIST_INSERT_HEAD(&source->shadow_head,
new_object, shadow_list);
source->shadow_count++;
source->generation++;
vm_object_reference_locked(source); /* for new_object */
vm_object_clear_flag(source, OBJ_ONEMAPPING);
VM_OBJECT_UNLOCK(source);
new_object->backing_object_offset =
@ -1623,7 +1645,6 @@ vm_object_collapse(vm_object_t object)
new_backing_object = backing_object->backing_object;
if ((object->backing_object = new_backing_object) != NULL) {
vm_object_reference(new_backing_object);
VM_OBJECT_LOCK(new_backing_object);
LIST_INSERT_HEAD(
&new_backing_object->shadow_head,
@ -1632,6 +1653,7 @@ vm_object_collapse(vm_object_t object)
);
new_backing_object->shadow_count++;
new_backing_object->generation++;
vm_object_reference_locked(new_backing_object);
VM_OBJECT_UNLOCK(new_backing_object);
object->backing_object_offset +=
backing_object->backing_object_offset;

1
sys/vm/vm_object.h
View File

@ -213,6 +213,7 @@ void vm_object_init (void);
void vm_object_page_clean (vm_object_t, vm_pindex_t, vm_pindex_t, boolean_t);
void vm_object_page_remove (vm_object_t, vm_pindex_t, vm_pindex_t, boolean_t);
void vm_object_reference (vm_object_t);
void vm_object_reference_locked(vm_object_t);
void vm_object_shadow (vm_object_t *, vm_ooffset_t *, vm_size_t);
void vm_object_split(vm_map_entry_t);
void vm_object_madvise (vm_object_t, vm_pindex_t, int, int);