net: sched: RCU cls_tcindex
Make cls_tcindex RCU safe. This patch addds a new RCU routine rcu_dereference_bh_rtnl() to check caller either holds the rcu read lock or RTNL. This is needed to handle the case where tcindex_lookup() is being called in both cases. Signed-off-by: John Fastabend <john.r.fastabend@intel.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
John Fastabend
David S. Miller
Родитель
1109c00547
Коммит
331b72922c
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@ -46,6 +46,16 @@ static inline int lockdep_rtnl_is_held(void)
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#define rcu_dereference_rtnl(p) \
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rcu_dereference_check(p, lockdep_rtnl_is_held())
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/**
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* rcu_dereference_bh_rtnl - rcu_dereference_bh with debug checking
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* @p: The pointer to read, prior to dereference
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*
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* Do an rcu_dereference_bh(p), but check caller either holds rcu_read_lock_bh()
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* or RTNL. Note : Please prefer rtnl_dereference() or rcu_dereference_bh()
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*/
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#define rcu_dereference_bh_rtnl(p) \
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rcu_dereference_bh_check(p, lockdep_rtnl_is_held())
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/**
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* rtnl_dereference - fetch RCU pointer when updates are prevented by RTNL
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* @p: The pointer to read, prior to dereferencing
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@ -32,19 +32,21 @@ struct tcindex_filter_result {
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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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struct tcindex_filter __rcu *next;
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struct rcu_head rcu;
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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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struct tcindex_filter __rcu **h; /* imperfect hash; */
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struct tcf_proto *tp;
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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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u32 shift; /* shift ANDed key to the right */
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u32 hash; /* hash table size; 0 if undefined */
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u32 alloc_hash; /* allocated size */
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u32 fall_through; /* 0: only classify if explicit match */
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struct rcu_head rcu;
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};
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static inline int
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@ -56,13 +58,18 @@ tcindex_filter_is_set(struct tcindex_filter_result *r)
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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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if (p->perfect) {
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struct tcindex_filter_result *f = p->perfect + key;
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return tcindex_filter_is_set(f) ? f : NULL;
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} else if (p->h) {
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struct tcindex_filter __rcu **fp;
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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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fp = &p->h[key % p->hash];
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for (f = rcu_dereference_bh_rtnl(*fp);
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f;
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fp = &f->next, f = rcu_dereference_bh_rtnl(*fp))
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if (f->key == key)
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return &f->result;
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}
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@ -74,7 +81,7 @@ tcindex_lookup(struct tcindex_data *p, u16 key)
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static int tcindex_classify(struct sk_buff *skb, const struct tcf_proto *tp,
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struct tcf_result *res)
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{
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struct tcindex_data *p = tp->root;
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struct tcindex_data *p = rcu_dereference(tp->root);
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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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@ -99,7 +106,7 @@ static int tcindex_classify(struct sk_buff *skb, const struct tcf_proto *tp,
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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 = tp->root;
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struct tcindex_data *p = rtnl_dereference(tp->root);
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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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@ -129,49 +136,59 @@ static int tcindex_init(struct tcf_proto *tp)
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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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rcu_assign_pointer(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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tcindex_delete(struct tcf_proto *tp, unsigned long arg)
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{
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struct tcindex_data *p = tp->root;
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struct tcindex_data *p = rtnl_dereference(tp->root);
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struct tcindex_filter_result *r = (struct tcindex_filter_result *) arg;
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struct tcindex_filter __rcu **walk;
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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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pr_debug("tcindex_delete(tp %p,arg 0x%lx),p %p\n", tp, arg, p);
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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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for (i = 0; i < p->hash; i++) {
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walk = p->h + i;
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for (f = rtnl_dereference(*walk); f;
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walk = &f->next, f = rtnl_dereference(*walk)) {
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if (&f->result == r)
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goto found;
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}
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}
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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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rcu_assign_pointer(*walk, rtnl_dereference(f->next));
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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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if (f)
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kfree_rcu(f, rcu);
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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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static int tcindex_destroy_element(struct tcf_proto *tp,
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unsigned long arg,
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struct tcf_walker *walker)
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{
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return __tcindex_delete(tp, arg, 1);
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return tcindex_delete(tp, arg);
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}
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static void __tcindex_destroy(struct rcu_head *head)
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{
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struct tcindex_data *p = container_of(head, struct tcindex_data, rcu);
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kfree(p->perfect);
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kfree(p->h);
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kfree(p);
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}
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static inline int
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@ -194,6 +211,14 @@ static void tcindex_filter_result_init(struct tcindex_filter_result *r)
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tcf_exts_init(&r->exts, TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
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}
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static void __tcindex_partial_destroy(struct rcu_head *head)
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{
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struct tcindex_data *p = container_of(head, struct tcindex_data, rcu);
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kfree(p->perfect);
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kfree(p);
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}
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static int
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tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
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u32 handle, struct tcindex_data *p,
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@ -203,7 +228,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
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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_data *cp, *oldp;
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struct tcindex_filter *f = NULL; /* make gcc behave */
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struct tcf_exts e;
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@ -212,84 +237,118 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
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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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tcindex_filter_result_init(&new_filter_result);
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/* tcindex_data attributes must look atomic to classifier/lookup so
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* allocate new tcindex data and RCU assign it onto root. Keeping
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* perfect hash and hash pointers from old data.
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*/
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cp = kzalloc(sizeof(cp), GFP_KERNEL);
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if (!cp)
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return -ENOMEM;
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cp->mask = p->mask;
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cp->shift = p->shift;
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cp->hash = p->hash;
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cp->alloc_hash = p->alloc_hash;
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cp->fall_through = p->fall_through;
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cp->tp = tp;
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if (p->perfect) {
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cp->perfect = kmemdup(p->perfect,
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sizeof(*r) * cp->hash, GFP_KERNEL);
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if (!cp->perfect)
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goto errout;
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}
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cp->h = p->h;
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memset(&new_filter_result, 0, sizeof(new_filter_result));
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tcf_exts_init(&new_filter_result.exts,
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TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
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tcindex_filter_result_init(&cr);
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if (old_r)
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cr.res = r->res;
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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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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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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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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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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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} else if (cp->h && cp->hash != cp->alloc_hash) {
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goto errout;
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}
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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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cp->fall_through = nla_get_u32(tb[TCA_TCINDEX_FALL_THROUGH]);
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if (!cp.hash) {
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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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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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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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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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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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if (!cp->perfect && !cp->h) {
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if (valid_perfect_hash(cp)) {
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int i;
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cp.perfect = kcalloc(cp.hash, sizeof(*r), GFP_KERNEL);
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if (!cp.perfect)
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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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for (i = 0; i < cp.hash; i++)
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tcf_exts_init(&cp.perfect[i].exts, TCA_TCINDEX_ACT,
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for (i = 0; i < cp->hash; i++)
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tcf_exts_init(&cp->perfect[i].exts,
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TCA_TCINDEX_ACT,
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TCA_TCINDEX_POLICE);
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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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struct tcindex_filter __rcu **hash;
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hash = kcalloc(cp->hash,
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sizeof(struct tcindex_filter *),
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GFP_KERNEL);
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if (!hash)
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goto errout;
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cp->h = hash;
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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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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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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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@ -307,33 +366,41 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
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else
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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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tcindex_filter_result_init(old_r);
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memcpy(p, &cp, sizeof(cp));
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oldp = p;
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r->res = cr.res;
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rcu_assign_pointer(tp->root, cp);
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if (r == &new_filter_result) {
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struct tcindex_filter **fp;
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struct tcindex_filter *nfp;
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struct tcindex_filter __rcu **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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fp = p->h + (handle % p->hash);
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for (nfp = rtnl_dereference(*fp);
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nfp;
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fp = &nfp->next, nfp = rtnl_dereference(*fp))
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; /* nothing */
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rcu_assign_pointer(*fp, f);
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}
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if (oldp)
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call_rcu(&oldp->rcu, __tcindex_partial_destroy);
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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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kfree(cp->perfect);
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else if (balloc == 2)
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kfree(cp.h);
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kfree(cp->h);
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errout:
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kfree(cp);
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tcf_exts_destroy(tp, &e);
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return err;
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}
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@ -345,7 +412,7 @@ tcindex_change(struct net *net, struct sk_buff *in_skb,
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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 = tp->root;
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struct tcindex_data *p = rtnl_dereference(tp->root);
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struct tcindex_filter_result *r = (struct tcindex_filter_result *) *arg;
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int err;
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@ -364,10 +431,9 @@ tcindex_change(struct net *net, struct sk_buff *in_skb,
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tca[TCA_RATE], ovr);
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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 = tp->root;
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struct tcindex_data *p = rtnl_dereference(tp->root);
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struct tcindex_filter *f, *next;
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int i;
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@ -390,8 +456,8 @@ static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
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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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for (f = rtnl_dereference(p->h[i]); f; f = next) {
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next = rtnl_dereference(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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@ -404,17 +470,9 @@ static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
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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,
|
||||
unsigned long arg, struct tcf_walker *walker)
|
||||
{
|
||||
return __tcindex_delete(tp, arg, 0);
|
||||
}
|
||||
|
||||
|
||||
static void tcindex_destroy(struct tcf_proto *tp)
|
||||
{
|
||||
struct tcindex_data *p = tp->root;
|
||||
struct tcindex_data *p = rtnl_dereference(tp->root);
|
||||
struct tcf_walker walker;
|
||||
|
||||
pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
|
||||
|
|
@ -422,17 +480,16 @@ static void tcindex_destroy(struct tcf_proto *tp)
|
|||
walker.skip = 0;
|
||||
walker.fn = tcindex_destroy_element;
|
||||
tcindex_walk(tp, &walker);
|
||||
kfree(p->perfect);
|
||||
kfree(p->h);
|
||||
kfree(p);
|
||||
tp->root = NULL;
|
||||
|
||||
RCU_INIT_POINTER(tp->root, NULL);
|
||||
call_rcu(&p->rcu, __tcindex_destroy);
|
||||
}
|
||||
|
||||
|
||||
static int tcindex_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
|
||||
struct sk_buff *skb, struct tcmsg *t)
|
||||
{
|
||||
struct tcindex_data *p = tp->root;
|
||||
struct tcindex_data *p = rtnl_dereference(tp->root);
|
||||
struct tcindex_filter_result *r = (struct tcindex_filter_result *) fh;
|
||||
unsigned char *b = skb_tail_pointer(skb);
|
||||
struct nlattr *nest;
|
||||
|
|
@ -455,15 +512,18 @@ static int tcindex_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
|
|||
nla_nest_end(skb, nest);
|
||||
} else {
|
||||
if (p->perfect) {
|
||||
t->tcm_handle = r-p->perfect;
|
||||
t->tcm_handle = r - p->perfect;
|
||||
} else {
|
||||
struct tcindex_filter *f;
|
||||
struct tcindex_filter __rcu **fp;
|
||||
int i;
|
||||
|
||||
t->tcm_handle = 0;
|
||||
for (i = 0; !t->tcm_handle && i < p->hash; i++) {
|
||||
for (f = p->h[i]; !t->tcm_handle && f;
|
||||
f = f->next) {
|
||||
fp = &p->h[i];
|
||||
for (f = rtnl_dereference(*fp);
|
||||
!t->tcm_handle && f;
|
||||
fp = &f->next, f = rtnl_dereference(*fp)) {
|
||||
if (&f->result == r)
|
||||
t->tcm_handle = f->key;
|
||||
}
|
||||
|
|
|
|||
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Ссылка в новой задаче