o Use Jenkins hash. With previous hash, for a single source IP address and
sequential IP ID case (e.g. ping -f), distribution fell into 8-10 buckets out of 64. With Jenkins hash, distribution is even. o Add random seed to the hash. Sponsored by: Nginx, Inc.
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=281352
@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/eventhandler.h>
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#include <sys/hash.h>
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#include <sys/mbuf.h>
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#include <sys/malloc.h>
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#include <sys/lock.h>
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@ -64,8 +65,6 @@ SYSCTL_DECL(_net_inet_ip);
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#define IPREASS_NHASH_LOG2 6
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#define IPREASS_NHASH (1 << IPREASS_NHASH_LOG2)
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#define IPREASS_HMASK (IPREASS_NHASH - 1)
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#define IPREASS_HASH(x,y) \
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(((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
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struct ipqbucket {
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TAILQ_HEAD(ipqhead, ipq) head;
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@ -74,6 +73,8 @@ struct ipqbucket {
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static VNET_DEFINE(struct ipqbucket, ipq[IPREASS_NHASH]);
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#define V_ipq VNET(ipq)
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static VNET_DEFINE(uint32_t, ipq_hashseed);
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#define V_ipq_hashseed VNET(ipq_hashseed)
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#define IPQ_LOCK(i) mtx_lock(&V_ipq[i].lock)
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#define IPQ_TRYLOCK(i) mtx_trylock(&V_ipq[i].lock)
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@ -146,7 +147,7 @@ ip_reass(struct mbuf *m)
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struct ipqhead *head;
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int i, hlen, next;
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u_int8_t ecn, ecn0;
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u_short hash;
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uint32_t hash;
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#ifdef RSS
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uint32_t rss_hash, rss_type;
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#endif
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@ -200,7 +201,8 @@ ip_reass(struct mbuf *m)
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m->m_data += hlen;
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m->m_len -= hlen;
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hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
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hash = ip->ip_src.s_addr ^ ip->ip_id;
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hash = jenkins_hash32(&hash, 1, V_ipq_hashseed) & IPREASS_HMASK;
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head = &V_ipq[hash].head;
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IPQ_LOCK(hash);
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@ -465,6 +467,7 @@ ipreass_init(void)
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mtx_init(&V_ipq[i].lock, "IP reassembly", NULL,
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MTX_DEF | MTX_DUPOK);
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}
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V_ipq_hashseed = arc4random();
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V_maxfragsperpacket = 16;
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V_ipq_zone = uma_zcreate("ipq", sizeof(struct ipq), NULL, NULL, NULL,
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NULL, UMA_ALIGN_PTR, 0);
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