Function crcowget

freebsd/kern/kern_prot.c:1852–1863

* Credential management. * * struct ucred objects are rarely allocated but gain and lose references all * the time (e.g., on struct file alloc/dealloc) turning refcount updates into * a significant source of cache-line ping ponging. Common cases are worked * around by modifying thread-local counter instead if the cred to operate on * matches td_realucred. * * The counter is split into 2 pa

 * accumulated updates.
 */
struct ucred *
crcowget(struct ucred *cr)
{

	mtx_lock(&cr->cr_mtx);
	KASSERT(cr->cr_users > 0, ("%s: users %d not > 0 on cred %p",
	    __func__, cr->cr_users, cr));
	cr->cr_users++;
	cr->cr_ref++;
	mtx_unlock(&cr->cr_mtx);
	return (cr);
}

static struct ucred *
crunuse(struct thread *td)