Author: mjg
Date: Fri Dec 7 16:22:54 2018
New Revision: 341699
URL: https://svnweb.freebsd.org/changeset/base/341699
Log:
vm: use fcmpset for vmspace reference counting
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/vm/vm_map.c
Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c Fri Dec 7 16:11:45 2018 (r341698)
+++ head/sys/vm/vm_map.c Fri Dec 7 16:22:54 2018 (r341699)
@@ -391,8 +391,8 @@ vmspace_exit(struct thread *td)
p = td->td_proc;
vm = p->p_vmspace;
atomic_add_int(&vmspace0.vm_refcnt, 1);
+ refcnt = vm->vm_refcnt;
do {
- refcnt = vm->vm_refcnt;
if (refcnt > 1 && p->p_vmspace != &vmspace0) {
/* Switch now since other proc might free vmspace */
PROC_VMSPACE_LOCK(p);
@@ -400,7 +400,7 @@ vmspace_exit(struct thread *td)
PROC_VMSPACE_UNLOCK(p);
pmap_activate(td);
}
- } while (!atomic_cmpset_int(&vm->vm_refcnt, refcnt, refcnt - 1));
+ } while (!atomic_fcmpset_int(&vm->vm_refcnt, &refcnt, refcnt - 1));
if (refcnt == 1) {
if (p->p_vmspace != vm) {
/* vmspace not yet freed, switch back */
@@ -437,13 +437,13 @@ vmspace_acquire_ref(struct proc *p)
PROC_VMSPACE_UNLOCK(p);
return (NULL);
}
+ refcnt = vm->vm_refcnt;
do {
- refcnt = vm->vm_refcnt;
if (refcnt <= 0) { /* Avoid 0->1 transition */
PROC_VMSPACE_UNLOCK(p);
return (NULL);
}
- } while (!atomic_cmpset_int(&vm->vm_refcnt, refcnt, refcnt + 1));
+ } while (!atomic_fcmpset_int(&vm->vm_refcnt, &refcnt, refcnt + 1));
if (vm != p->p_vmspace) {
PROC_VMSPACE_UNLOCK(p);
vmspace_free(vm);
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