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Fix outgoing TCP/UDP packet drop on arp/ndp entry expiration.

Browse Source 
Current arp/nd code relies on the feedback from the datapath indicating
 that the entry is still used. This mechanism is incorporated into the
 arpresolve()/nd6_resolve() routines. After the inpcb route cache
 introduction, the packet path for the locally-originated packets changed,
 passing cached lle pointer to the ether_output() directly. This resulted
 in the arp/ndp entry expire each time exactly after the configured max_age
 interval. During the small window between the ARP/NDP request and reply
 from the router, most of the packets got lost.

Fix this behaviour by plugging datapath notification code to the packet
 path used by route cache. Unify the notification code by using single
 inlined function with the per-AF callbacks.

Reported by:	sthaug at nethelp.no
Reviewed by:	ae
MFC after:	2 weeks
This commit is contained in:
melifaro 2018-03-17 17:05:48 +00:00
parent bf523f13ef
commit 7bb5ee0db4
5 changed files with 60 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
sys/net/if_ethersubr.c
View File

@ -311,7 +311,13 @@ ether_output(struct ifnet *ifp, struct mbuf *m,
if (lle == NULL) {
/* if we lookup, keep cache */
addref = 1;
}
} else
/*
* Notify LLE code that
* the entry was used
* by datapath.
*/
llentry_mark_used(lle);
}
if (lle != NULL) {
phdr = lle->r_linkdata;

15
sys/net/if_llatbl.h
View File

@ -149,6 +149,7 @@ typedef void (llt_fill_sa_entry_t)(const struct llentry *, struct sockaddr *);
typedef void (llt_free_tbl_t)(struct lltable *);
typedef void (llt_link_entry_t)(struct lltable *, struct llentry *);
typedef void (llt_unlink_entry_t)(struct llentry *);
typedef void (llt_mark_used_t)(struct llentry *);
typedef int (llt_foreach_cb_t)(struct lltable *, struct llentry *, void *);
typedef int (llt_foreach_entry_t)(struct lltable *, llt_foreach_cb_t *, void *);
@ -173,6 +174,7 @@ struct lltable {
llt_unlink_entry_t *llt_unlink_entry;
llt_fill_sa_entry_t *llt_fill_sa_entry;
llt_free_tbl_t *llt_free_tbl;
llt_mark_used_t *llt_mark_used;
};
MALLOC_DECLARE(M_LLTABLE);
@ -247,6 +249,19 @@ lla_lookup(struct lltable *llt, u_int flags, const struct sockaddr *l3addr)
return (llt->llt_lookup(llt, flags, l3addr));
}
/*
* Notify the LLE code that the entry was used by datapath.
*/
static __inline void
llentry_mark_used(struct llentry *lle)
{
if (lle->r_skip_req == 0)
return;
if ((lle->r_flags & RLLE_VALID) != 0)
lle->lle_tbl->llt_mark_used(lle);
}
int lla_rt_output(struct rt_msghdr *, struct rt_addrinfo *);
#include <sys/eventhandler.h>

16
sys/netinet/if_ether.c
View File

@ -504,12 +504,8 @@ arpresolve_full(struct ifnet *ifp, int is_gw, int flags, struct mbuf *m,
}
bcopy(lladdr, desten, ll_len);
/* Check if we have feedback request from arptimer() */
if (la->r_skip_req != 0) {
LLE_REQ_LOCK(la);
la->r_skip_req = 0; /* Notify that entry was used */
LLE_REQ_UNLOCK(la);
}
/* Notify LLE code that the entry was used by datapath */
llentry_mark_used(la);
if (pflags != NULL)
*pflags = la->la_flags & (LLE_VALID|LLE_IFADDR);
if (plle) {
@ -640,12 +636,8 @@ arpresolve(struct ifnet *ifp, int is_gw, struct mbuf *m,
bcopy(la->r_linkdata, desten, la->r_hdrlen);
if (pflags != NULL)
*pflags = LLE_VALID | (la->r_flags & RLLE_IFADDR);
/* Check if we have feedback request from arptimer() */
if (la->r_skip_req != 0) {
LLE_REQ_LOCK(la);
la->r_skip_req = 0; /* Notify that entry was used */
LLE_REQ_UNLOCK(la);
}
/* Notify the LLE handling code that the entry was used. */
llentry_mark_used(la);
if (plle) {
LLE_ADDREF(la);
*plle = la;

14
sys/netinet/in.c
View File

@ -1067,6 +1067,19 @@ in_lltable_destroy_lle_unlocked(struct llentry *lle)
free(lle, M_LLTABLE);
}
/*
* Called by the datapath to indicate that
* the entry was used.
*/
static void
in_lltable_mark_used(struct llentry *lle)
{
LLE_REQ_LOCK(lle);
lle->r_skip_req = 0;
LLE_REQ_UNLOCK(lle);
}
/*
* Called by LLE_FREE_LOCKED when number of references
* drops to zero.
@ -1470,6 +1483,7 @@ in_lltattach(struct ifnet *ifp)
llt->llt_fill_sa_entry = in_lltable_fill_sa_entry;
llt->llt_free_entry = in_lltable_free_entry;
llt->llt_match_prefix = in_lltable_match_prefix;
llt->llt_mark_used = in_lltable_mark_used;
lltable_link(llt);
return (llt);

20
sys/netinet6/in6.c
View File

@ -2148,6 +2148,25 @@ in6_lltable_rtcheck(struct ifnet *ifp,
return 0;
}
/*
* Called by the datapath to indicate that the entry was used.
*/
static void
in6_lltable_mark_used(struct llentry *lle)
{
LLE_REQ_LOCK(lle);
lle->r_skip_req = 0;
/*
* Set the hit time so the callback function
* can determine the remaining time before
* transiting to the DELAY state.
*/
lle->lle_hittime = time_uptime;
LLE_REQ_UNLOCK(lle);
}
static inline uint32_t
in6_lltable_hash_dst(const struct in6_addr *dst, uint32_t hsize)
{
@ -2380,6 +2399,7 @@ in6_lltattach(struct ifnet *ifp)
llt->llt_fill_sa_entry = in6_lltable_fill_sa_entry;
llt->llt_free_entry = in6_lltable_free_entry;
llt->llt_match_prefix = in6_lltable_match_prefix;
llt->llt_mark_used = in6_lltable_mark_used;
lltable_link(llt);
return (llt);