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vm: use fcmpset for vmspace reference counting

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Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Mateusz Guzik 2018-12-07 16:22:54 +00:00
parent 6ff4688b09
commit 83764b446a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=341699
1 changed files with 4 additions and 4 deletions
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8
sys/vm/vm_map.c
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@ -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);