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Split arpresolve() into fast/slow path.

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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
This commit is contained in:
melifaro 2015-08-16 12:23:58 +00:00
parent cbebdcf01c
commit bc522110e3
1 changed files with 93 additions and 61 deletions
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154
sys/netinet/if_ether.c
View File

@ -309,57 +309,37 @@ arprequest(struct ifnet *ifp, const struct in_addr *sip,
}
/*
* Resolve an IP address into an ethernet address.
* On input:
* ifp is the interface we use
* is_gw != if @dst represents gateway to some destination
* m is the mbuf. May be NULL if we don't have a packet.
* dst is the next hop,
* desten is where we want the address.
* flags returns lle entry flags.
* Resolve an IP address into an ethernet address - heavy version.
* Used internally by arpresolve().
* We have already checked than we can't use existing lle without
* modification so we have to acquire LLE_EXCLUSIVE lle lock.
*
* On success, desten and flags are filled in and the function returns 0;
* If the packet must be held pending resolution, we return EWOULDBLOCK
* On other errors, we return the corresponding error code.
* Note that m_freem() handles NULL.
*/
int
arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
static int
arpresolve_full(struct ifnet *ifp, int is_gw, int create, struct mbuf *m,
const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
{
struct llentry *la = 0;
u_int flags = 0;
struct llentry *la = NULL;
struct mbuf *curr = NULL;
struct mbuf *next = NULL;
int create, error, renew;
int error, renew;
if (pflags != NULL)
*pflags = 0;
create = 0;
if (m != NULL) {
if (m->m_flags & M_BCAST) {
/* broadcast */
(void)memcpy(desten,
ifp->if_broadcastaddr, ifp->if_addrlen);
return (0);
}
if (m->m_flags & M_MCAST) {
/* multicast */
ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
return (0);
}
if (create == 0) {
IF_AFDATA_RLOCK(ifp);
la = lla_lookup(LLTABLE(ifp), LLE_EXCLUSIVE, dst);
IF_AFDATA_RUNLOCK(ifp);
}
retry:
IF_AFDATA_RLOCK(ifp);
la = lla_lookup(LLTABLE(ifp), flags, dst);
IF_AFDATA_RUNLOCK(ifp);
if ((la == NULL) && ((flags & LLE_EXCLUSIVE) == 0)
&& ((ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0)) {
if (la == NULL && (ifp->if_flags & (IFF_NOARP | IFF_STATICARP)) == 0) {
create = 1;
flags |= LLE_EXCLUSIVE;
IF_AFDATA_WLOCK(ifp);
la = lla_create(LLTABLE(ifp), flags, dst);
la = lla_create(LLTABLE(ifp), 0, dst);
IF_AFDATA_WUNLOCK(ifp);
}
if (la == NULL) {
@ -389,10 +369,7 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
if (pflags != NULL)
*pflags = la->la_flags;
if (flags & LLE_EXCLUSIVE)
LLE_WUNLOCK(la);
else
LLE_RUNLOCK(la);
LLE_WUNLOCK(la);
if (renew == 1)
arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
@ -400,20 +377,7 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
return (0);
}
if (la->la_flags & LLE_STATIC) { /* should not happen! */
log(LOG_DEBUG, "arpresolve: ouch, empty static llinfo for %s\n",
inet_ntoa(SIN(dst)->sin_addr));
m_freem(m);
error = EINVAL;
goto done;
}
renew = (la->la_asked == 0 || la->la_expire != time_uptime);
if ((renew || m != NULL) && (flags & LLE_EXCLUSIVE) == 0) {
flags |= LLE_EXCLUSIVE;
LLE_RUNLOCK(la);
goto retry;
}
/*
* There is an arptab entry, but no ethernet address
* response yet. Add the mbuf to the list, dropping
@ -438,11 +402,6 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
} else
la->la_hold = m;
la->la_numheld++;
if (renew == 0 && (flags & LLE_EXCLUSIVE)) {
flags &= ~LLE_EXCLUSIVE;
LLE_DOWNGRADE(la);
}
}
/*
* Return EWOULDBLOCK if we have tried less than arp_maxtries. It
@ -469,14 +428,87 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
return (error);
}
done:
if (flags & LLE_EXCLUSIVE)
LLE_WUNLOCK(la);
else
LLE_RUNLOCK(la);
LLE_WUNLOCK(la);
return (error);
}
/*
* Resolve an IP address into an ethernet address.
* On input:
* ifp is the interface we use
* is_gw != 0 if @dst represents gateway to some destination
* m is the mbuf. May be NULL if we don't have a packet.
* dst is the next hop,
* desten is the storage to put LL address.
* flags returns lle entry flags.
*
* On success, desten and flags are filled in and the function returns 0;
* If the packet must be held pending resolution, we return EWOULDBLOCK
* On other errors, we return the corresponding error code.
* Note that m_freem() handles NULL.
*/
int
arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
const struct sockaddr *dst, u_char *desten, uint32_t *pflags)
{
struct llentry *la = 0;
int renew;
if (pflags != NULL)
*pflags = 0;
if (m != NULL) {
if (m->m_flags & M_BCAST) {
/* broadcast */
(void)memcpy(desten,
ifp->if_broadcastaddr, ifp->if_addrlen);
return (0);
}
if (m->m_flags & M_MCAST) {
/* multicast */
ETHER_MAP_IP_MULTICAST(&SIN(dst)->sin_addr, desten);
return (0);
}
}
IF_AFDATA_RLOCK(ifp);
la = lla_lookup(LLTABLE(ifp), 0, dst);
IF_AFDATA_RUNLOCK(ifp);
if (la == NULL)
return (arpresolve_full(ifp, is_gw, 1, m, dst, desten, pflags));
if ((la->la_flags & LLE_VALID) &&
((la->la_flags & LLE_STATIC) || la->la_expire > time_uptime)) {
bcopy(&la->ll_addr, desten, ifp->if_addrlen);
renew = 0;
/*
* If entry has an expiry time and it is approaching,
* see if we need to send an ARP request within this
* arpt_down interval.
*/
if (!(la->la_flags & LLE_STATIC) &&
time_uptime + la->la_preempt > la->la_expire) {
renew = 1;
la->la_preempt--;
}
if (pflags != NULL)
*pflags = la->la_flags;
LLE_RUNLOCK(la);
if (renew == 1)
arprequest(ifp, NULL, &SIN(dst)->sin_addr, NULL);
return (0);
}
LLE_RUNLOCK(la);
return (arpresolve_full(ifp, is_gw, 0, m, dst, desten, pflags));
}
/*
* Common length and type checks are done here,
* then the protocol-specific routine is called.