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![Patrick McHardy](/assets/img/avatar_default.png)
The use of xchg() hasn't been necessary since 2.2.something when proper locking was added to packet schedulers. In the case of classifiers they mostly weren't even necessary before that since they're mainly used to assign a NULL pointer to the filter root in the ->destroy path; the root is destroyed immediately after that. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
506 lines
12 KiB
C
506 lines
12 KiB
C
/*
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* net/sched/cls_tcindex.c Packet classifier for skb->tc_index
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*
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* Written 1998,1999 by Werner Almesberger, EPFL ICA
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/errno.h>
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#include <net/act_api.h>
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#include <net/netlink.h>
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#include <net/pkt_cls.h>
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/*
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* Passing parameters to the root seems to be done more awkwardly than really
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* necessary. At least, u32 doesn't seem to use such dirty hacks. To be
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* verified. FIXME.
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*/
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#define PERFECT_HASH_THRESHOLD 64 /* use perfect hash if not bigger */
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#define DEFAULT_HASH_SIZE 64 /* optimized for diffserv */
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#define PRIV(tp) ((struct tcindex_data *) (tp)->root)
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struct tcindex_filter_result {
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struct tcf_exts exts;
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struct tcf_result res;
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};
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struct tcindex_filter {
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u16 key;
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struct tcindex_filter_result result;
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struct tcindex_filter *next;
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};
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struct tcindex_data {
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struct tcindex_filter_result *perfect; /* perfect hash; NULL if none */
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struct tcindex_filter **h; /* imperfect hash; only used if !perfect;
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NULL if unused */
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u16 mask; /* AND key with mask */
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int shift; /* shift ANDed key to the right */
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int hash; /* hash table size; 0 if undefined */
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int alloc_hash; /* allocated size */
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int fall_through; /* 0: only classify if explicit match */
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};
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static const struct tcf_ext_map tcindex_ext_map = {
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.police = TCA_TCINDEX_POLICE,
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.action = TCA_TCINDEX_ACT
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};
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static inline int
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tcindex_filter_is_set(struct tcindex_filter_result *r)
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{
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return tcf_exts_is_predicative(&r->exts) || r->res.classid;
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}
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static struct tcindex_filter_result *
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tcindex_lookup(struct tcindex_data *p, u16 key)
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{
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struct tcindex_filter *f;
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if (p->perfect)
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return tcindex_filter_is_set(p->perfect + key) ?
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p->perfect + key : NULL;
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else if (p->h) {
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for (f = p->h[key % p->hash]; f; f = f->next)
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if (f->key == key)
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return &f->result;
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}
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return NULL;
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}
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static int tcindex_classify(struct sk_buff *skb, struct tcf_proto *tp,
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struct tcf_result *res)
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{
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struct tcindex_data *p = PRIV(tp);
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struct tcindex_filter_result *f;
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int key = (skb->tc_index & p->mask) >> p->shift;
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pr_debug("tcindex_classify(skb %p,tp %p,res %p),p %p\n",
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skb, tp, res, p);
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f = tcindex_lookup(p, key);
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if (!f) {
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if (!p->fall_through)
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return -1;
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res->classid = TC_H_MAKE(TC_H_MAJ(tp->q->handle), key);
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res->class = 0;
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pr_debug("alg 0x%x\n", res->classid);
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return 0;
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}
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*res = f->res;
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pr_debug("map 0x%x\n", res->classid);
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return tcf_exts_exec(skb, &f->exts, res);
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}
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static unsigned long tcindex_get(struct tcf_proto *tp, u32 handle)
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{
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struct tcindex_data *p = PRIV(tp);
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struct tcindex_filter_result *r;
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pr_debug("tcindex_get(tp %p,handle 0x%08x)\n", tp, handle);
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if (p->perfect && handle >= p->alloc_hash)
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return 0;
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r = tcindex_lookup(p, handle);
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return r && tcindex_filter_is_set(r) ? (unsigned long) r : 0UL;
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}
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static void tcindex_put(struct tcf_proto *tp, unsigned long f)
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{
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pr_debug("tcindex_put(tp %p,f 0x%lx)\n", tp, f);
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}
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static int tcindex_init(struct tcf_proto *tp)
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{
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struct tcindex_data *p;
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pr_debug("tcindex_init(tp %p)\n", tp);
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p = kzalloc(sizeof(struct tcindex_data), GFP_KERNEL);
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if (!p)
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return -ENOMEM;
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p->mask = 0xffff;
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p->hash = DEFAULT_HASH_SIZE;
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p->fall_through = 1;
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tp->root = p;
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return 0;
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}
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static int
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__tcindex_delete(struct tcf_proto *tp, unsigned long arg, int lock)
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{
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struct tcindex_data *p = PRIV(tp);
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struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
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struct tcindex_filter *f = NULL;
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pr_debug("tcindex_delete(tp %p,arg 0x%lx),p %p,f %p\n", tp, arg, p, f);
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if (p->perfect) {
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if (!r->res.class)
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return -ENOENT;
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} else {
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int i;
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struct tcindex_filter **walk = NULL;
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for (i = 0; i < p->hash; i++)
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for (walk = p->h+i; *walk; walk = &(*walk)->next)
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if (&(*walk)->result == r)
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goto found;
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return -ENOENT;
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found:
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f = *walk;
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if (lock)
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tcf_tree_lock(tp);
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*walk = f->next;
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if (lock)
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tcf_tree_unlock(tp);
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}
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tcf_unbind_filter(tp, &r->res);
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tcf_exts_destroy(tp, &r->exts);
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kfree(f);
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return 0;
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}
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static int tcindex_delete(struct tcf_proto *tp, unsigned long arg)
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{
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return __tcindex_delete(tp, arg, 1);
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}
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static inline int
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valid_perfect_hash(struct tcindex_data *p)
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{
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return p->hash > (p->mask >> p->shift);
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}
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static const struct nla_policy tcindex_policy[TCA_TCINDEX_MAX + 1] = {
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[TCA_TCINDEX_HASH] = { .type = NLA_U32 },
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[TCA_TCINDEX_MASK] = { .type = NLA_U16 },
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[TCA_TCINDEX_SHIFT] = { .type = NLA_U32 },
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[TCA_TCINDEX_FALL_THROUGH] = { .type = NLA_U32 },
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[TCA_TCINDEX_CLASSID] = { .type = NLA_U32 },
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};
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static int
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tcindex_set_parms(struct tcf_proto *tp, unsigned long base, u32 handle,
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struct tcindex_data *p, struct tcindex_filter_result *r,
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struct nlattr **tb, struct nlattr *est)
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{
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int err, balloc = 0;
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struct tcindex_filter_result new_filter_result, *old_r = r;
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struct tcindex_filter_result cr;
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struct tcindex_data cp;
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struct tcindex_filter *f = NULL; /* make gcc behave */
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struct tcf_exts e;
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err = tcf_exts_validate(tp, tb, est, &e, &tcindex_ext_map);
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if (err < 0)
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return err;
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memcpy(&cp, p, sizeof(cp));
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memset(&new_filter_result, 0, sizeof(new_filter_result));
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if (old_r)
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memcpy(&cr, r, sizeof(cr));
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else
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memset(&cr, 0, sizeof(cr));
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if (tb[TCA_TCINDEX_HASH])
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cp.hash = nla_get_u32(tb[TCA_TCINDEX_HASH]);
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if (tb[TCA_TCINDEX_MASK])
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cp.mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);
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if (tb[TCA_TCINDEX_SHIFT])
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cp.shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
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err = -EBUSY;
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/* Hash already allocated, make sure that we still meet the
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* requirements for the allocated hash.
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*/
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if (cp.perfect) {
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if (!valid_perfect_hash(&cp) ||
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cp.hash > cp.alloc_hash)
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goto errout;
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} else if (cp.h && cp.hash != cp.alloc_hash)
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goto errout;
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err = -EINVAL;
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if (tb[TCA_TCINDEX_FALL_THROUGH])
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cp.fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]);
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if (!cp.hash) {
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/* Hash not specified, use perfect hash if the upper limit
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* of the hashing index is below the threshold.
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*/
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if ((cp.mask >> cp.shift) < PERFECT_HASH_THRESHOLD)
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cp.hash = (cp.mask >> cp.shift)+1;
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else
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cp.hash = DEFAULT_HASH_SIZE;
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}
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if (!cp.perfect && !cp.h)
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cp.alloc_hash = cp.hash;
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/* Note: this could be as restrictive as if (handle & ~(mask >> shift))
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* but then, we'd fail handles that may become valid after some future
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* mask change. While this is extremely unlikely to ever matter,
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* the check below is safer (and also more backwards-compatible).
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*/
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if (cp.perfect || valid_perfect_hash(&cp))
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if (handle >= cp.alloc_hash)
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goto errout;
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err = -ENOMEM;
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if (!cp.perfect && !cp.h) {
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if (valid_perfect_hash(&cp)) {
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cp.perfect = kcalloc(cp.hash, sizeof(*r), GFP_KERNEL);
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if (!cp.perfect)
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goto errout;
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balloc = 1;
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} else {
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cp.h = kcalloc(cp.hash, sizeof(f), GFP_KERNEL);
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if (!cp.h)
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goto errout;
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balloc = 2;
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}
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}
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if (cp.perfect)
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r = cp.perfect + handle;
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else
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r = tcindex_lookup(&cp, handle) ? : &new_filter_result;
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if (r == &new_filter_result) {
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f = kzalloc(sizeof(*f), GFP_KERNEL);
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if (!f)
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goto errout_alloc;
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}
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if (tb[TCA_TCINDEX_CLASSID]) {
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cr.res.classid = nla_get_u32(tb[TCA_TCINDEX_CLASSID]);
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tcf_bind_filter(tp, &cr.res, base);
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}
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tcf_exts_change(tp, &cr.exts, &e);
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tcf_tree_lock(tp);
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if (old_r && old_r != r)
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memset(old_r, 0, sizeof(*old_r));
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memcpy(p, &cp, sizeof(cp));
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memcpy(r, &cr, sizeof(cr));
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if (r == &new_filter_result) {
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struct tcindex_filter **fp;
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f->key = handle;
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f->result = new_filter_result;
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f->next = NULL;
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for (fp = p->h+(handle % p->hash); *fp; fp = &(*fp)->next)
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/* nothing */;
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*fp = f;
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}
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tcf_tree_unlock(tp);
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return 0;
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errout_alloc:
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if (balloc == 1)
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kfree(cp.perfect);
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else if (balloc == 2)
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kfree(cp.h);
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errout:
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tcf_exts_destroy(tp, &e);
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return err;
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}
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static int
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tcindex_change(struct tcf_proto *tp, unsigned long base, u32 handle,
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struct nlattr **tca, unsigned long *arg)
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{
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struct nlattr *opt = tca[TCA_OPTIONS];
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struct nlattr *tb[TCA_TCINDEX_MAX + 1];
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struct tcindex_data *p = PRIV(tp);
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struct tcindex_filter_result *r = (struct tcindex_filter_result *) *arg;
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int err;
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pr_debug("tcindex_change(tp %p,handle 0x%08x,tca %p,arg %p),opt %p,"
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"p %p,r %p,*arg 0x%lx\n",
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tp, handle, tca, arg, opt, p, r, arg ? *arg : 0L);
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if (!opt)
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return 0;
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err = nla_parse_nested(tb, TCA_TCINDEX_MAX, opt, tcindex_policy);
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if (err < 0)
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return err;
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return tcindex_set_parms(tp, base, handle, p, r, tb, tca[TCA_RATE]);
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}
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static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
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{
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struct tcindex_data *p = PRIV(tp);
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struct tcindex_filter *f, *next;
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int i;
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pr_debug("tcindex_walk(tp %p,walker %p),p %p\n", tp, walker, p);
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if (p->perfect) {
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for (i = 0; i < p->hash; i++) {
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if (!p->perfect[i].res.class)
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continue;
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if (walker->count >= walker->skip) {
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if (walker->fn(tp,
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(unsigned long) (p->perfect+i), walker)
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< 0) {
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walker->stop = 1;
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return;
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}
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}
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walker->count++;
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}
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}
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if (!p->h)
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return;
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for (i = 0; i < p->hash; i++) {
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for (f = p->h[i]; f; f = next) {
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next = f->next;
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if (walker->count >= walker->skip) {
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if (walker->fn(tp, (unsigned long) &f->result,
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walker) < 0) {
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walker->stop = 1;
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return;
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}
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}
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walker->count++;
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}
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}
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}
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static int tcindex_destroy_element(struct tcf_proto *tp,
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unsigned long arg, struct tcf_walker *walker)
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{
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return __tcindex_delete(tp, arg, 0);
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}
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static void tcindex_destroy(struct tcf_proto *tp)
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{
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struct tcindex_data *p = PRIV(tp);
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struct tcf_walker walker;
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pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
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walker.count = 0;
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walker.skip = 0;
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walker.fn = &tcindex_destroy_element;
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tcindex_walk(tp, &walker);
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kfree(p->perfect);
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kfree(p->h);
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kfree(p);
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tp->root = NULL;
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}
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static int tcindex_dump(struct tcf_proto *tp, unsigned long fh,
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struct sk_buff *skb, struct tcmsg *t)
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{
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struct tcindex_data *p = PRIV(tp);
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struct tcindex_filter_result *r = (struct tcindex_filter_result *) fh;
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unsigned char *b = skb_tail_pointer(skb);
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struct nlattr *nest;
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pr_debug("tcindex_dump(tp %p,fh 0x%lx,skb %p,t %p),p %p,r %p,b %p\n",
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tp, fh, skb, t, p, r, b);
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pr_debug("p->perfect %p p->h %p\n", p->perfect, p->h);
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nest = nla_nest_start(skb, TCA_OPTIONS);
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if (nest == NULL)
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goto nla_put_failure;
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if (!fh) {
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t->tcm_handle = ~0; /* whatever ... */
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NLA_PUT_U32(skb, TCA_TCINDEX_HASH, p->hash);
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NLA_PUT_U16(skb, TCA_TCINDEX_MASK, p->mask);
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NLA_PUT_U32(skb, TCA_TCINDEX_SHIFT, p->shift);
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NLA_PUT_U32(skb, TCA_TCINDEX_FALL_THROUGH, p->fall_through);
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nla_nest_end(skb, nest);
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} else {
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if (p->perfect) {
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t->tcm_handle = r-p->perfect;
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} else {
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struct tcindex_filter *f;
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int i;
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t->tcm_handle = 0;
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for (i = 0; !t->tcm_handle && i < p->hash; i++) {
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for (f = p->h[i]; !t->tcm_handle && f;
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f = f->next) {
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if (&f->result == r)
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t->tcm_handle = f->key;
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}
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}
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}
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pr_debug("handle = %d\n", t->tcm_handle);
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if (r->res.class)
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NLA_PUT_U32(skb, TCA_TCINDEX_CLASSID, r->res.classid);
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if (tcf_exts_dump(skb, &r->exts, &tcindex_ext_map) < 0)
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goto nla_put_failure;
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nla_nest_end(skb, nest);
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if (tcf_exts_dump_stats(skb, &r->exts, &tcindex_ext_map) < 0)
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goto nla_put_failure;
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}
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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return -1;
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}
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static struct tcf_proto_ops cls_tcindex_ops __read_mostly = {
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.kind = "tcindex",
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.classify = tcindex_classify,
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.init = tcindex_init,
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.destroy = tcindex_destroy,
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.get = tcindex_get,
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.put = tcindex_put,
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.change = tcindex_change,
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.delete = tcindex_delete,
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.walk = tcindex_walk,
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.dump = tcindex_dump,
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.owner = THIS_MODULE,
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};
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static int __init init_tcindex(void)
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{
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return register_tcf_proto_ops(&cls_tcindex_ops);
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}
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static void __exit exit_tcindex(void)
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{
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unregister_tcf_proto_ops(&cls_tcindex_ops);
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}
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module_init(init_tcindex)
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module_exit(exit_tcindex)
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MODULE_LICENSE("GPL");
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