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Various changes to vm_object_shadow(): (1) update the vm_object locking,

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(2) remove a pointless assertion, and (3) make a trivial change to a
comment.
This commit is contained in:
Alan Cox 2003-04-27 05:43:03 +00:00
parent 32660658b8
commit 570a2f4ac5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=114112
1 changed files with 16 additions and 13 deletions
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29
sys/vm/vm_object.c
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@ -1078,26 +1078,29 @@ vm_object_shadow(
vm_object_t source; vm_object_t source;
vm_object_t result; vm_object_t result;
GIANT_REQUIRED;
source = *object; source = *object;
vm_object_lock(source);
/* /*
* Don't create the new object if the old object isn't shared. * Don't create the new object if the old object isn't shared.
*/ */
if (source != NULL && if (source != NULL) {
source->ref_count == 1 && VM_OBJECT_LOCK(source);
source->handle == NULL && if (source->ref_count == 1 &&
(source->type == OBJT_DEFAULT || source->handle == NULL &&
source->type == OBJT_SWAP)) { (source->type == OBJT_DEFAULT ||
vm_object_unlock(source); source->type == OBJT_SWAP)) {
return; VM_OBJECT_UNLOCK(source);
return;
}
VM_OBJECT_UNLOCK(source);
} }
/* /*
* Allocate a new object with the given length * Allocate a new object with the given length.
*/ */
result = vm_object_allocate(OBJT_DEFAULT, length); result = vm_object_allocate(OBJT_DEFAULT, length);
KASSERT(result != NULL, ("vm_object_shadow: no object for shadowing"));
/* /*
* The new object shadows the source object, adding a reference to it. * The new object shadows the source object, adding a reference to it.
@ -1110,7 +1113,8 @@ vm_object_shadow(
* shadowed object. * shadowed object.
*/ */
result->backing_object = source; result->backing_object = source;
if (source) { if (source != NULL) {
VM_OBJECT_LOCK(source);
TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list); TAILQ_INSERT_TAIL(&source->shadow_head, result, shadow_list);
source->shadow_count++; source->shadow_count++;
source->generation++; source->generation++;
@ -1121,6 +1125,7 @@ vm_object_shadow(
length = PQ_L2_SIZE / 3 + PQ_PRIME1; length = PQ_L2_SIZE / 3 + PQ_PRIME1;
result->pg_color = (source->pg_color + result->pg_color = (source->pg_color +
length * source->generation) & PQ_L2_MASK; length * source->generation) & PQ_L2_MASK;
VM_OBJECT_UNLOCK(source);
next_index = (result->pg_color + PQ_L2_SIZE / 3 + PQ_PRIME1) & next_index = (result->pg_color + PQ_L2_SIZE / 3 + PQ_PRIME1) &
PQ_L2_MASK; PQ_L2_MASK;
} }
@ -1136,8 +1141,6 @@ vm_object_shadow(
*/ */
*offset = 0; *offset = 0;
*object = result; *object = result;
vm_object_unlock(source);
} }
/* /*