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diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -88,7 +88,14 @@
#include <netlink/netlink_route.h>
#include <netlink/route/route_var.h>
-#define VLAN_DEF_HWIDTH 4
+/* For a fixed-width hash list, the value 8 realizes a list 256 entries wide.
+ * With 4094 unique VLAN possibilities per interface, this provides an absolute
+ * maximum VLAN chain length of 16 entries. Performance testing with iperf3
+ * suggests that acceptable performance is maintained with chain lengths up to
+ * 32. Picking a length of 16 allows for margin.
+ */
+#define VLAN_HWIDTH 8
+#define VLAN_HMASK ((1 << VLAN_HWIDTH) - 1)
#define VLAN_IFFLAGS (IFF_BROADCAST | IFF_MULTICAST)
#define UP_AND_RUNNING(ifp) \
@@ -104,8 +111,6 @@
struct ifvlan *vlans[VLAN_ARRAY_SIZE]; /* static table */
#else
struct ifvlanhead *hash; /* dynamic hash-list table */
- uint16_t hmask;
- uint16_t hwidth;
#endif
int refcnt;
};
@@ -137,7 +142,7 @@
#define VLAN_FOREACH(_ifv, _trunk) \
struct ifvlan *_next; \
size_t _i; \
- for (_i = 0; _i < (1 << (_trunk)->hwidth); _i++) \
+ for (_i = 0; _i < (1 << VLAN_HWIDTH); _i++) \
CK_SLIST_FOREACH_SAFE((_ifv), &(_trunk)->hash[_i], ifv_list, _next)
#endif /* VLAN_ARRAY */
@@ -165,7 +170,7 @@
size_t _i; \
bool _touch = false; \
for (_i = 0; \
- !(_cond) && _i < (1 << (_trunk)->hwidth); \
+ !(_cond) && _i < (1 << VLAN_HWIDTH); \
_i = (_touch && ((_trunk) != NULL) ? 0 : _i + 1), _touch = false) \
if (((_ifv) = CK_SLIST_FIRST(&(_trunk)->hash[_i])) != NULL && \
(_touch = true))
@@ -277,7 +282,6 @@
static void vlan_freehash(struct ifvlantrunk *trunk);
static int vlan_inshash(struct ifvlantrunk *trunk, struct ifvlan *ifv);
static int vlan_remhash(struct ifvlantrunk *trunk, struct ifvlan *ifv);
-static void vlan_growhash(struct ifvlantrunk *trunk, int howmuch);
static __inline struct ifvlan * vlan_gethash(struct ifvlantrunk *trunk,
uint16_t vid);
#endif
@@ -388,7 +392,7 @@
}
#ifndef VLAN_ARRAY
-#define HASH(n, m) ((((n) >> 8) ^ ((n) >> 4) ^ (n)) & (m))
+#define HASH(n) ((((n) >> 8) ^ ((n) >> 4) ^ (n)) & VLAN_HMASK)
static void
vlan_inithash(struct ifvlantrunk *trunk)
@@ -401,12 +405,9 @@
* gets hooked up and becomes visible from other threads.
*/
- KASSERT(trunk->hwidth == 0 && trunk->hash == NULL,
- ("%s: hash already initialized", __func__));
+ KASSERT(trunk->hash == NULL, ("%s: hash already initialized", __func__));
- trunk->hwidth = VLAN_DEF_HWIDTH;
- n = 1 << trunk->hwidth;
- trunk->hmask = n - 1;
+ n = 1 << VLAN_HWIDTH;
trunk->hash = malloc(sizeof(struct ifvlanhead) * n, M_VLAN, M_WAITOK);
for (i = 0; i < n; i++)
CK_SLIST_INIT(&trunk->hash[i]);
@@ -418,40 +419,27 @@
#ifdef INVARIANTS
int i;
- KASSERT(trunk->hwidth > 0, ("%s: hwidth not positive", __func__));
- for (i = 0; i < (1 << trunk->hwidth); i++)
+ for (i = 0; i <= VLAN_HMASK; i++)
KASSERT(CK_SLIST_EMPTY(&trunk->hash[i]),
("%s: hash table not empty", __func__));
#endif
free(trunk->hash, M_VLAN);
trunk->hash = NULL;
- trunk->hwidth = trunk->hmask = 0;
}
static int
vlan_inshash(struct ifvlantrunk *trunk, struct ifvlan *ifv)
{
- int i, b;
+ int i;
struct ifvlan *ifv2;
VLAN_XLOCK_ASSERT();
- KASSERT(trunk->hwidth > 0, ("%s: hwidth not positive", __func__));
- b = 1 << trunk->hwidth;
- i = HASH(ifv->ifv_vid, trunk->hmask);
+ i = HASH(ifv->ifv_vid);
CK_SLIST_FOREACH(ifv2, &trunk->hash[i], ifv_list)
if (ifv->ifv_vid == ifv2->ifv_vid)
return (EEXIST);
- /*
- * Grow the hash when the number of vlans exceeds half of the number of
- * hash buckets squared. This will make the average linked-list length
- * buckets/2.
- */
- if (trunk->refcnt > (b * b) / 2) {
- vlan_growhash(trunk, 1);
- i = HASH(ifv->ifv_vid, trunk->hmask);
- }
CK_SLIST_INSERT_HEAD(&trunk->hash[i], ifv, ifv_list);
trunk->refcnt++;
@@ -461,20 +449,16 @@
static int
vlan_remhash(struct ifvlantrunk *trunk, struct ifvlan *ifv)
{
- int i, b;
+ int i;
struct ifvlan *ifv2;
VLAN_XLOCK_ASSERT();
- KASSERT(trunk->hwidth > 0, ("%s: hwidth not positive", __func__));
- b = 1 << (trunk->hwidth - 1);
- i = HASH(ifv->ifv_vid, trunk->hmask);
+ i = HASH(ifv->ifv_vid);
CK_SLIST_FOREACH(ifv2, &trunk->hash[i], ifv_list)
if (ifv2 == ifv) {
trunk->refcnt--;
CK_SLIST_REMOVE(&trunk->hash[i], ifv2, ifvlan, ifv_list);
- if (trunk->refcnt < (b * b) / 2)
- vlan_growhash(trunk, -1);
return (0);
}
@@ -482,52 +466,6 @@
return (ENOENT); /*NOTREACHED*/
}
-/*
- * Grow the hash larger or smaller if memory permits.
- */
-static void
-vlan_growhash(struct ifvlantrunk *trunk, int howmuch)
-{
- struct ifvlan *ifv;
- struct ifvlanhead *hash2;
- int hwidth2, i, j, n, n2;
-
- VLAN_XLOCK_ASSERT();
- KASSERT(trunk->hwidth > 0, ("%s: hwidth not positive", __func__));
-
- if (howmuch == 0) {
- /* Harmless yet obvious coding error */
- printf("%s: howmuch is 0\n", __func__);
- return;
- }
-
- hwidth2 = trunk->hwidth + howmuch;
- n = 1 << trunk->hwidth;
- n2 = 1 << hwidth2;
- /* Do not shrink the table below the default */
- if (hwidth2 < VLAN_DEF_HWIDTH)
- return;
-
- hash2 = malloc(sizeof(struct ifvlanhead) * n2, M_VLAN, M_WAITOK);
- for (j = 0; j < n2; j++)
- CK_SLIST_INIT(&hash2[j]);
- for (i = 0; i < n; i++)
- while ((ifv = CK_SLIST_FIRST(&trunk->hash[i])) != NULL) {
- CK_SLIST_REMOVE(&trunk->hash[i], ifv, ifvlan, ifv_list);
- j = HASH(ifv->ifv_vid, n2 - 1);
- CK_SLIST_INSERT_HEAD(&hash2[j], ifv, ifv_list);
- }
- NET_EPOCH_WAIT();
- free(trunk->hash, M_VLAN);
- trunk->hash = hash2;
- trunk->hwidth = hwidth2;
- trunk->hmask = n2 - 1;
-
- if (bootverbose)
- if_printf(trunk->parent,
- "VLAN hash table resized from %d to %d buckets\n", n, n2);
-}
-
static __inline struct ifvlan *
vlan_gethash(struct ifvlantrunk *trunk, uint16_t vid)
{
@@ -535,7 +473,7 @@
NET_EPOCH_ASSERT();
- CK_SLIST_FOREACH(ifv, &trunk->hash[HASH(vid, trunk->hmask)], ifv_list)
+ CK_SLIST_FOREACH(ifv, &trunk->hash[HASH(vid)], ifv_list)
if (ifv->ifv_vid == vid)
return (ifv);
return (NULL);
@@ -549,7 +487,7 @@
int i;
struct ifvlan *ifv;
- for (i = 0; i < (1 << trunk->hwidth); i++) {
+ for (i = 0; i <= VLAN_HMASK; i++) {
printf("%d: ", i);
CK_SLIST_FOREACH(ifv, &trunk->hash[i], ifv_list)
printf("%s ", ifv->ifv_ifp->if_xname);

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