net: sched: rcu'ify cls_bpf
This patch makes the cls_bpf classifier RCU safe. The tcf_lock was being used to protect a list of cls_bpf_prog now this list is RCU safe and updates occur with rcu_replace. 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
parent
b929d86d25
commit
1f947bf151
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@ -27,6 +27,7 @@ MODULE_DESCRIPTION("TC BPF based classifier");
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struct cls_bpf_head {
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struct list_head plist;
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u32 hgen;
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struct rcu_head rcu;
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};
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struct cls_bpf_prog {
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@ -37,6 +38,8 @@ struct cls_bpf_prog {
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struct list_head link;
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u32 handle;
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u16 bpf_len;
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struct tcf_proto *tp;
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struct rcu_head rcu;
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};
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static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
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@ -49,11 +52,11 @@ static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
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static int cls_bpf_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 cls_bpf_head *head = tp->root;
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struct cls_bpf_head *head = rcu_dereference(tp->root);
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struct cls_bpf_prog *prog;
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int ret;
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list_for_each_entry(prog, &head->plist, link) {
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list_for_each_entry_rcu(prog, &head->plist, link) {
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int filter_res = BPF_PROG_RUN(prog->filter, skb);
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if (filter_res == 0)
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@ -81,8 +84,8 @@ static int cls_bpf_init(struct tcf_proto *tp)
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if (head == NULL)
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return -ENOBUFS;
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INIT_LIST_HEAD(&head->plist);
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tp->root = head;
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INIT_LIST_HEAD_RCU(&head->plist);
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rcu_assign_pointer(tp->root, head);
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return 0;
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}
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@ -98,18 +101,22 @@ static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog)
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kfree(prog);
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}
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static void __cls_bpf_delete_prog(struct rcu_head *rcu)
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{
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struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);
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cls_bpf_delete_prog(prog->tp, prog);
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}
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static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
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{
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struct cls_bpf_head *head = tp->root;
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *prog, *todel = (struct cls_bpf_prog *) arg;
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list_for_each_entry(prog, &head->plist, link) {
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if (prog == todel) {
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tcf_tree_lock(tp);
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list_del(&prog->link);
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tcf_tree_unlock(tp);
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cls_bpf_delete_prog(tp, prog);
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list_del_rcu(&prog->link);
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call_rcu(&prog->rcu, __cls_bpf_delete_prog);
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return 0;
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}
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}
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@ -119,27 +126,28 @@ static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)
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static void cls_bpf_destroy(struct tcf_proto *tp)
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{
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struct cls_bpf_head *head = tp->root;
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *prog, *tmp;
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list_for_each_entry_safe(prog, tmp, &head->plist, link) {
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list_del(&prog->link);
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cls_bpf_delete_prog(tp, prog);
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list_del_rcu(&prog->link);
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call_rcu(&prog->rcu, __cls_bpf_delete_prog);
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}
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kfree(head);
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RCU_INIT_POINTER(tp->root, NULL);
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kfree_rcu(head, rcu);
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}
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static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)
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{
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struct cls_bpf_head *head = tp->root;
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *prog;
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unsigned long ret = 0UL;
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if (head == NULL)
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return 0UL;
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list_for_each_entry(prog, &head->plist, link) {
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list_for_each_entry_rcu(prog, &head->plist, link) {
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if (prog->handle == handle) {
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ret = (unsigned long) prog;
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break;
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@ -158,10 +166,10 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
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unsigned long base, struct nlattr **tb,
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struct nlattr *est, bool ovr)
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{
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struct sock_filter *bpf_ops, *bpf_old;
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struct sock_filter *bpf_ops;
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struct tcf_exts exts;
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struct sock_fprog_kern tmp;
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struct bpf_prog *fp, *fp_old;
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struct bpf_prog *fp;
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u16 bpf_size, bpf_len;
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u32 classid;
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int ret;
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@ -197,26 +205,15 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp,
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if (ret)
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goto errout_free;
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tcf_tree_lock(tp);
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fp_old = prog->filter;
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bpf_old = prog->bpf_ops;
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prog->bpf_len = bpf_len;
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prog->bpf_ops = bpf_ops;
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prog->filter = fp;
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prog->res.classid = classid;
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tcf_tree_unlock(tp);
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tcf_bind_filter(tp, &prog->res, base);
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tcf_exts_change(tp, &prog->exts, &exts);
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if (fp_old)
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bpf_prog_destroy(fp_old);
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if (bpf_old)
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kfree(bpf_old);
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return 0;
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errout_free:
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kfree(bpf_ops);
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errout:
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@ -244,9 +241,10 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
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u32 handle, struct nlattr **tca,
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unsigned long *arg, bool ovr)
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{
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struct cls_bpf_head *head = tp->root;
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struct cls_bpf_prog *prog = (struct cls_bpf_prog *) *arg;
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg;
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struct nlattr *tb[TCA_BPF_MAX + 1];
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struct cls_bpf_prog *prog;
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int ret;
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if (tca[TCA_OPTIONS] == NULL)
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@ -256,18 +254,19 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
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if (ret < 0)
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return ret;
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if (prog != NULL) {
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if (handle && prog->handle != handle)
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return -EINVAL;
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return cls_bpf_modify_existing(net, tp, prog, base, tb,
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tca[TCA_RATE], ovr);
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}
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prog = kzalloc(sizeof(*prog), GFP_KERNEL);
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if (prog == NULL)
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if (!prog)
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return -ENOBUFS;
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tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE);
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if (oldprog) {
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if (handle && oldprog->handle != handle) {
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ret = -EINVAL;
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goto errout;
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}
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}
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if (handle == 0)
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prog->handle = cls_bpf_grab_new_handle(tp, head);
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else
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@ -281,16 +280,17 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
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if (ret < 0)
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goto errout;
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tcf_tree_lock(tp);
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list_add(&prog->link, &head->plist);
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tcf_tree_unlock(tp);
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if (oldprog) {
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list_replace_rcu(&prog->link, &oldprog->link);
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call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
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} else {
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list_add_rcu(&prog->link, &head->plist);
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}
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*arg = (unsigned long) prog;
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return 0;
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errout:
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if (*arg == 0UL && prog)
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kfree(prog);
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kfree(prog);
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return ret;
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}
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@ -339,10 +339,10 @@ static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
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static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)
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{
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struct cls_bpf_head *head = tp->root;
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struct cls_bpf_head *head = rtnl_dereference(tp->root);
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struct cls_bpf_prog *prog;
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list_for_each_entry(prog, &head->plist, link) {
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list_for_each_entry_rcu(prog, &head->plist, link) {
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if (arg->count < arg->skip)
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goto skip;
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if (arg->fn(tp, (unsigned long) prog, arg) < 0) {
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