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Avoid acquiring the object lock if color is already set. It can not be

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unset until the object is recycled so this check is stable.  Now that we
can acquire the ref without a lock it is not necessary to group these
operations and we can avoid it entirely in many cases.

Reviewed by:	kib, markj
Differential Revision:	https://reviews.freebsd.org/D22565
This commit is contained in:
Jeff Roberson 2019-11-29 19:49:20 +00:00
parent 26c4e9831b
commit f2410510db
1 changed files with 6 additions and 4 deletions
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10
sys/vm/vm_mmap.c
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@ -1325,12 +1325,14 @@ vm_mmap_vnode(struct thread *td, vm_size_t objsize,
} else {
KASSERT(obj->type == OBJT_DEFAULT || obj->type == OBJT_SWAP,
("wrong object type"));
VM_OBJECT_WLOCK(obj);
vm_object_reference_locked(obj);
vm_object_reference(obj);
#if VM_NRESERVLEVEL > 0
vm_object_color(obj, 0);
if ((obj->flags & OBJ_COLORED) == 0) {
VM_OBJECT_WLOCK(obj);
vm_object_color(obj, 0);
VM_OBJECT_WUNLOCK(obj);
}
#endif
VM_OBJECT_WUNLOCK(obj);
}
*objp = obj;
*flagsp = flags;