Split arpresolve() into fast/slow path.
This change isolates the most common case (e.g. successful lookup) from more complicates scenarios. It also (tries to) make code more simple by avoiding retry: cycle. The actual goal is to prepare code to the upcoming change that will allow LL address retrieval without acquiring LLE lock at all. Reviewed by: ae Differential Revision: https://reviews.freebsd.org/D3383
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b3667a140d
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512e30ef9f
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=286825
@ -309,57 +309,37 @@ arprequest(struct ifnet *ifp, const struct in_addr *sip,
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}
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/*
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* Resolve an IP address into an ethernet address.
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* On input:
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* ifp is the interface we use
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* is_gw != if @dst represents gateway to some destination
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* m is the mbuf. May be NULL if we don't have a packet.
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* dst is the next hop,
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* desten is where we want the address.
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* flags returns lle entry flags.
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* Resolve an IP address into an ethernet address - heavy version.
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* Used internally by arpresolve().
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* We have already checked than we can't use existing lle without
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* modification so we have to acquire LLE_EXCLUSIVE lle lock.
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*
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* On success, desten and flags are filled in and the function returns 0;
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* If the packet must be held pending resolution, we return EWOULDBLOCK
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* On other errors, we return the corresponding error code.
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* Note that m_freem() handles NULL.
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*/
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int
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arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
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static int
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arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf *m,
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const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
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{
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struct llentry *la = 0;
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u_int flags = 0;
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struct llentry *la = NULL;
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struct mbuf *curr = NULL;
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struct mbuf *next = NULL;
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int create, error, renew;
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int error, renew;
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if (pflags != NULL)
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*pflags = 0;
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create = 0;
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if (m != NULL) {
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if (m->m_flags & M_BCAST) {
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/* broadcast */
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(void)memcpy(desten,
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ifp->if_broadcastaddr, ifp->if_addrlen);
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return (0);
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}
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if (m->m_flags & M_MCAST) {
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/* multicast */
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ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
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return (0);
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}
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if (create == 0) {
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IF_AFDATA_RLOCK(ifp);
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la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
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IF_AFDATA_RUNLOCK(ifp);
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}
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retry:
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IF_AFDATA_RLOCK(ifp);
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la = lla_lookup(LLTABLE(ifp), flags, dst);
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IF_AFDATA_RUNLOCK(ifp);
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if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
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&& ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
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if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
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create = 1;
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flags |= LLE_EXCLUSIVE;
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IF_AFDATA_WLOCK(ifp);
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la = lla_create(LLTABLE(ifp), flags, dst);
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la = lla_create(LLTABLE(ifp), 0, dst);
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IF_AFDATA_WUNLOCK(ifp);
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}
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if (la == NULL) {
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@ -389,10 +369,7 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
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if (pflags != NULL)
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*pflags = la->la_flags;
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if (flags & LLE_EXCLUSIVE)
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LLE_WUNLOCK(la);
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else
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LLE_RUNLOCK(la);
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LLE_WUNLOCK(la);
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if (renew == 1)
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arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
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@ -400,20 +377,7 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
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return (0);
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}
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if (la->la_flags & LLE_STATIC) { /* should not happen! */
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log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
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inet_ntoa(SIN(dst)->sin_addr));
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m_freem(m);
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error = EINVAL;
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goto done;
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}
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renew = (la->la_asked == 0 || la->la_expire != time_uptime);
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if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
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flags |= LLE_EXCLUSIVE;
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LLE_RUNLOCK(la);
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goto retry;
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}
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/*
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* There is an arptab entry, but no ethernet address
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* response yet. Add the mbuf to the list, dropping
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@ -438,11 +402,6 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
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} else
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la->la_hold = m;
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la->la_numheld++;
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if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
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flags &= ~LLE_EXCLUSIVE;
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LLE_DOWNGRADE(la);
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}
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}
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/*
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* Return EWOULDBLOCK if we have tried less than arp_maxtries. It
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@ -469,14 +428,87 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
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arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
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return (error);
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}
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done:
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if (flags & LLE_EXCLUSIVE)
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LLE_WUNLOCK(la);
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else
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LLE_RUNLOCK(la);
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LLE_WUNLOCK(la);
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return (error);
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}
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/*
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* Resolve an IP address into an ethernet address.
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* On input:
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* ifp is the interface we use
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* is_gw != 0 if @dst represents gateway to some destination
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* m is the mbuf. May be NULL if we don't have a packet.
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* dst is the next hop,
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* desten is the storage to put LL address.
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* flags returns lle entry flags.
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*
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* On success, desten and flags are filled in and the function returns 0;
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* If the packet must be held pending resolution, we return EWOULDBLOCK
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* On other errors, we return the corresponding error code.
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* Note that m_freem() handles NULL.
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*/
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int
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arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
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const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
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{
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struct llentry *la = 0;
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int renew;
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if (pflags != NULL)
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*pflags = 0;
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if (m != NULL) {
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if (m->m_flags & M_BCAST) {
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/* broadcast */
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(void)memcpy(desten,
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ifp->if_broadcastaddr, ifp->if_addrlen);
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return (0);
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}
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if (m->m_flags & M_MCAST) {
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/* multicast */
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ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
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return (0);
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}
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}
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IF_AFDATA_RLOCK(ifp);
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la = lla_lookup(LLTABLE(ifp), 0, dst);
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IF_AFDATA_RUNLOCK(ifp);
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if (la == NULL)
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return (arpresolve_full(ifp, is_gw, 1, m, dst, desten, pflags));
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if ((la->la_flags & LLE_VALID) &&
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((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
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bcopy(&la->ll_addr, desten, ifp->if_addrlen);
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renew = 0;
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/*
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* If entry has an expiry time and it is approaching,
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* see if we need to send an ARP request within this
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* arpt_down interval.
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*/
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if (!(la->la_flags & LLE_STATIC) &&
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time_uptime + la->la_preempt > la->la_expire) {
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renew = 1;
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la->la_preempt--;
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}
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if (pflags != NULL)
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*pflags = la->la_flags;
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LLE_RUNLOCK(la);
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if (renew == 1)
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arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
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return (0);
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}
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LLE_RUNLOCK(la);
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return (arpresolve_full(ifp, is_gw, 0, m, dst, desten, pflags));
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}
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/*
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* Common length and type checks are done here,
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* then the protocol-specific routine is called.
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