/*
* Called with a modifying token held, but must still obtain p_spin to
* actually replace p_ucred to handle races against syscall entry from
* other threads which cache p_ucred->td_ucred.
*
* (the threads will only get the spin-lock, and they only need to in
* the case where td_ucred != p_ucred so this is optimal).
*/
struct ucred *
cratom_proc(struct proc *p)
{
struct ucred *oldcr;
struct ucred *newcr;
oldcr = p->p_ucred;
if (oldcr->cr_ref == 1)
return(oldcr);
newcr = crget(); /* this might block */
oldcr = p->p_ucred; /* so re-cache oldcr (do not re-test) */
*newcr = *oldcr;
if (newcr->cr_uidinfo)
uihold(newcr->cr_uidinfo);
if (newcr->cr_ruidinfo)
uihold(newcr->cr_ruidinfo);
if (jailed(newcr))
prison_hold(newcr->cr_prison);
newcr->cr_ref = 1;
spin_lock(&p->p_spin);
p->p_ucred = newcr;
spin_unlock(&p->p_spin);
crfree(oldcr);
return newcr;
}
/*
* Dup cred struct to a new held one.
*/
struct ucred *
crdup(struct ucred *cr)
{
struct ucred *newcr;
newcr = crget();
*newcr = *cr;
if (newcr->cr_uidinfo)
uihold(newcr->cr_uidinfo);
if (newcr->cr_ruidinfo)
uihold(newcr->cr_ruidinfo);
if (jailed(newcr))
prison_hold(newcr->cr_prison);
newcr->cr_ref = 1;
return (newcr);
}
/*
* Copy cred structure to a new one and free the old one.
*
* MPSAFE (*cr must be stable)
*/
struct ucred *
crcopy(struct ucred *cr)
{
struct ucred *newcr;
if (cr->cr_ref == 1)
return (cr);
newcr = crget();
*newcr = *cr;
if (newcr->cr_uidinfo)
uihold(newcr->cr_uidinfo);
if (newcr->cr_ruidinfo)
uihold(newcr->cr_ruidinfo);
if (jailed(newcr))
prison_hold(newcr->cr_prison);
newcr->cr_ref = 1;
crfree(cr);
return (newcr);
}
/*
* Atomize a cred structure so it can be modified without polluting
* other references to it.
*
* MPSAFE (however, *pcr must be stable)
*/
struct ucred *
cratom(struct ucred **pcr)
{
struct ucred *oldcr;
struct ucred *newcr;
oldcr = *pcr;
if (oldcr->cr_ref == 1)
return (oldcr);
newcr = crget();
*newcr = *oldcr;
if (newcr->cr_uidinfo)
uihold(newcr->cr_uidinfo);
if (newcr->cr_ruidinfo)
uihold(newcr->cr_ruidinfo);
if (jailed(newcr))
prison_hold(newcr->cr_prison);
newcr->cr_ref = 1;
crfree(oldcr);
*pcr = newcr;
return (newcr);
}
/*
* Atomize a cred structure so it can be modified without polluting
* other references to it.
*
* MPSAFE (however, *pcr must be stable)
*/
struct ucred *
cratom(struct ucred **pcr)
{
struct ucred *oldcr;
struct ucred *newcr;
oldcr = *pcr;
if (oldcr->cr_ref == 1)
return (oldcr);
newcr = crget(); /* this might block */
oldcr = *pcr; /* re-cache after potentially blocking */
*newcr = *oldcr;
if (newcr->cr_uidinfo)
uihold(newcr->cr_uidinfo);
if (newcr->cr_ruidinfo)
uihold(newcr->cr_ruidinfo);
if (jailed(newcr))
prison_hold(newcr->cr_prison);
newcr->cr_ref = 1;
crfree(oldcr);
*pcr = newcr;
return (newcr);
}
