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Add vm object locking.

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This commit is contained in:
Alan Cox 2003-06-11 06:43:48 +00:00
parent f79c46d3f4
commit c40f7377a4
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=116195
1 changed files with 12 additions and 12 deletions
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24
sys/kern/sys_process.c
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@ -149,7 +149,7 @@ proc_rwmem(struct proc *p, struct uio *uio)
{
struct vmspace *vm;
vm_map_t map;
vm_object_t object = NULL;
vm_object_t backing_object, object = NULL;
vm_offset_t pageno = 0; /* page number */
vm_prot_t reqprot;
vm_offset_t kva;
@ -239,19 +239,19 @@ proc_rwmem(struct proc *p, struct uio *uio)
break;
}
m = vm_page_lookup(object, pindex);
/* Allow fallback to backing objects if we are reading */
while (m == NULL && !writing && object->backing_object) {
VM_OBJECT_LOCK(object);
while ((m = vm_page_lookup(object, pindex)) == NULL &&
!writing &&
(backing_object = object->backing_object) != NULL) {
/*
* Allow fallback to backing objects if we are reading.
*/
VM_OBJECT_LOCK(backing_object);
pindex += OFF_TO_IDX(object->backing_object_offset);
object = object->backing_object;
m = vm_page_lookup(object, pindex);
VM_OBJECT_UNLOCK(object);
object = backing_object;
}
VM_OBJECT_UNLOCK(object);
if (m == NULL) {
error = EFAULT;