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Make sure that the object being collapsed doesn't go away on us...by

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gaining extra references to it.

Submitted by:	John Dyson
Obtained from:
This commit is contained in:
David Greenman 1995-01-05 04:30:40 +00:00
parent f81dd52383
commit 010cf3b9e3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=5404
1 changed files with 13 additions and 3 deletions
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16
sys/vm/vm_object.c
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@ -61,7 +61,7 @@
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*
* $Id: vm_object.c,v 1.12 1994/12/11 01:36:53 davidg Exp $
* $Id: vm_object.c,v 1.13 1994/12/23 05:00:19 davidg Exp $
*/
/*
@ -251,8 +251,13 @@ vm_object_deallocate(object)
*/
vm_object_lock(object);
if (--(object->ref_count) != 0) {
if( object->ref_count == 1)
vm_object_rcollapse(object->reverse_shadow_head.tqh_first, object);
if( object->ref_count == 1) {
if( object->reverse_shadow_head.tqh_first) {
++object->reverse_shadow_head.tqh_first->ref_count;
vm_object_rcollapse(object->reverse_shadow_head.tqh_first, object);
vm_object_deallocate(object->reverse_shadow_head.tqh_first);
}
}
vm_object_unlock(object);
/*
@ -1162,6 +1167,7 @@ vm_object_rcollapse(object, sobject)
if (backing_object->ref_count != 1)
return;
backing_object->ref_count += 2;
s = splbio();
while( backing_object->paging_in_progress) {
tsleep( backing_object, PVM, "rcolow", 0);
@ -1201,6 +1207,7 @@ vm_object_rcollapse(object, sobject)
}
p = next;
}
backing_object->ref_count -= 2;
}
/*
@ -1228,6 +1235,8 @@ vm_object_qcollapse(object)
if (backing_object->ref_count != 1)
return;
backing_object->ref_count += 2;
backing_offset = object->shadow_offset;
size = object->size;
p = backing_object->memq.tqh_first;
@ -1266,6 +1275,7 @@ vm_object_qcollapse(object)
}
p = next;
}
backing_object->ref_count -= 2;
}
boolean_t vm_object_collapse_allowed = TRUE;