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Code Issues Releases Activity

Reduce code duplication in merging vm_entry neighbors.

Browse Source 
Submitted by:	Doug Moore <dougm@rice.edu>
Reviewed by:	markj
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D17610
This commit is contained in:
Konstantin Belousov 2018-10-20 23:08:04 +00:00
parent 05bc9aa78f
commit 074244628b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=339506
1 changed files with 47 additions and 52 deletions
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99
sys/vm/vm_map.c
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@ -1643,6 +1643,49 @@ vm_map_find_min(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
}
}
static bool
vm_map_mergeable_neighbors(vm_map_entry_t prev, vm_map_entry_t entry)
{
vm_size_t prevsize;
prevsize = prev->end - prev->start;
return (prev->end == entry->start &&
prev->object.vm_object == entry->object.vm_object &&
(prev->object.vm_object == NULL ||
prev->offset + prevsize == entry->offset) &&
prev->eflags == entry->eflags &&
prev->protection == entry->protection &&
prev->max_protection == entry->max_protection &&
prev->inheritance == entry->inheritance &&
prev->wired_count == entry->wired_count &&
prev->cred == entry->cred);
}
static void
vm_map_merged_neighbor_dispose(vm_map_t map, vm_map_entry_t entry)
{
/*
* If the backing object is a vnode object,
* vm_object_deallocate() calls vrele().
* However, vrele() does not lock the vnode
* because the vnode has additional
* references. Thus, the map lock can be kept
* without causing a lock-order reversal with
* the vnode lock.
*
* Since we count the number of virtual page
* mappings in object->un_pager.vnp.writemappings,
* the writemappings value should not be adjusted
* when the entry is disposed of.
*/
if (entry->object.vm_object != NULL)
vm_object_deallocate(entry->object.vm_object);
if (entry->cred != NULL)
crfree(entry->cred);
vm_map_entry_dispose(map, entry);
}
/*
* vm_map_simplify_entry:
*
@ -1659,7 +1702,6 @@ void
vm_map_simplify_entry(vm_map_t map, vm_map_entry_t entry)
{
vm_map_entry_t next, prev;
vm_size_t prevsize, esize;
if ((entry->eflags & (MAP_ENTRY_GROWS_DOWN | MAP_ENTRY_GROWS_UP |
MAP_ENTRY_IN_TRANSITION | MAP_ENTRY_IS_SUB_MAP)) != 0)
@ -1667,70 +1709,23 @@ vm_map_simplify_entry(vm_map_t map, vm_map_entry_t entry)
prev = entry->prev;
if (prev != &map->header) {
prevsize = prev->end - prev->start;
if ( (prev->end == entry->start) &&
(prev->object.vm_object == entry->object.vm_object) &&
(!prev->object.vm_object ||
(prev->offset + prevsize == entry->offset)) &&
(prev->eflags == entry->eflags) &&
(prev->protection == entry->protection) &&
(prev->max_protection == entry->max_protection) &&
(prev->inheritance == entry->inheritance) &&
(prev->wired_count == entry->wired_count) &&
(prev->cred == entry->cred)) {
if (vm_map_mergeable_neighbors(prev, entry)) {
vm_map_entry_unlink(map, prev);
entry->start = prev->start;
entry->offset = prev->offset;
if (entry->prev != &map->header)
vm_map_entry_resize_free(map, entry->prev);
/*
* If the backing object is a vnode object,
* vm_object_deallocate() calls vrele().
* However, vrele() does not lock the vnode
* because the vnode has additional
* references. Thus, the map lock can be kept
* without causing a lock-order reversal with
* the vnode lock.
*
* Since we count the number of virtual page
* mappings in object->un_pager.vnp.writemappings,
* the writemappings value should not be adjusted
* when the entry is disposed of.
*/
if (prev->object.vm_object)
vm_object_deallocate(prev->object.vm_object);
if (prev->cred != NULL)
crfree(prev->cred);
vm_map_entry_dispose(map, prev);
vm_map_merged_neighbor_dispose(map, prev);
}
}
next = entry->next;
if (next != &map->header) {
esize = entry->end - entry->start;
if ((entry->end == next->start) &&
(next->object.vm_object == entry->object.vm_object) &&
(!entry->object.vm_object ||
(entry->offset + esize == next->offset)) &&
(next->eflags == entry->eflags) &&
(next->protection == entry->protection) &&
(next->max_protection == entry->max_protection) &&
(next->inheritance == entry->inheritance) &&
(next->wired_count == entry->wired_count) &&
(next->cred == entry->cred)) {
if (vm_map_mergeable_neighbors(entry, next)) {
vm_map_entry_unlink(map, next);
entry->end = next->end;
vm_map_entry_resize_free(map, entry);
/*
* See comment above.
*/
if (next->object.vm_object)
vm_object_deallocate(next->object.vm_object);
if (next->cred != NULL)
crfree(next->cred);
vm_map_entry_dispose(map, next);
vm_map_merged_neighbor_dispose(map, next);
}
}
}