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Commit 1f947bf1 authored by John Fastabend's avatar John Fastabend Committed by David S. Miller
Browse files

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: default avatarJohn Fastabend <john.r.fastabend@intel.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b929d86d

net/sched/cls_bpf.c

+47 −47
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ MODULE_DESCRIPTION("TC BPF based classifier"); 
struct cls_bpf_head {

	struct list_head plist;

	u32 hgen;

	struct rcu_head rcu;

};



struct cls_bpf_prog {
@@ -37,6 +38,8 @@ struct cls_bpf_prog { 
	struct list_head link;

	u32 handle;

	u16 bpf_len;

	struct tcf_proto *tp;

	struct rcu_head rcu;

};



static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = {
@@ -49,11 +52,11 @@ static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { 
static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,

			    struct tcf_result *res)

{

	struct cls_bpf_head *head = tp->root;

	struct cls_bpf_head *head = rcu_dereference(tp->root);

	struct cls_bpf_prog *prog;

	int ret;



	list_for_each_entry(prog, &head->plist, link) {

	list_for_each_entry_rcu(prog, &head->plist, link) {

		int filter_res = BPF_PROG_RUN(prog->filter, skb);



		if (filter_res == 0)
@@ -81,8 +84,8 @@ static int cls_bpf_init(struct tcf_proto *tp) 
	if (head == NULL)

		return -ENOBUFS;



	INIT_LIST_HEAD(&head->plist);

	tp->root = head;

	INIT_LIST_HEAD_RCU(&head->plist);

	rcu_assign_pointer(tp->root, head);



	return 0;

}
@@ -98,18 +101,22 @@ static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) 
	kfree(prog);

}



static void __cls_bpf_delete_prog(struct rcu_head *rcu)

{

	struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu);



	cls_bpf_delete_prog(prog->tp, prog);

}



static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg)

{

	struct cls_bpf_head *head = tp->root;

	struct cls_bpf_head *head = rtnl_dereference(tp->root);

	struct cls_bpf_prog *prog, *todel = (struct cls_bpf_prog *) arg;



	list_for_each_entry(prog, &head->plist, link) {

		if (prog == todel) {

			tcf_tree_lock(tp);

			list_del(&prog->link);

			tcf_tree_unlock(tp);



			cls_bpf_delete_prog(tp, prog);

			list_del_rcu(&prog->link);

			call_rcu(&prog->rcu, __cls_bpf_delete_prog);

			return 0;

		}

	}
@@ -119,27 +126,28 @@ static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) 


static void cls_bpf_destroy(struct tcf_proto *tp)

{

	struct cls_bpf_head *head = tp->root;

	struct cls_bpf_head *head = rtnl_dereference(tp->root);

	struct cls_bpf_prog *prog, *tmp;



	list_for_each_entry_safe(prog, tmp, &head->plist, link) {

		list_del(&prog->link);

		cls_bpf_delete_prog(tp, prog);

		list_del_rcu(&prog->link);

		call_rcu(&prog->rcu, __cls_bpf_delete_prog);

	}



	kfree(head);

	RCU_INIT_POINTER(tp->root, NULL);

	kfree_rcu(head, rcu);

}



static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle)

{

	struct cls_bpf_head *head = tp->root;

	struct cls_bpf_head *head = rtnl_dereference(tp->root);

	struct cls_bpf_prog *prog;

	unsigned long ret = 0UL;



	if (head == NULL)

		return 0UL;



	list_for_each_entry(prog, &head->plist, link) {

	list_for_each_entry_rcu(prog, &head->plist, link) {

		if (prog->handle == handle) {

			ret = (unsigned long) prog;

			break;
@@ -158,10 +166,10 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, 
				   unsigned long base, struct nlattr **tb,

				   struct nlattr *est, bool ovr)

{

	struct sock_filter *bpf_ops, *bpf_old;

	struct sock_filter *bpf_ops;

	struct tcf_exts exts;

	struct sock_fprog_kern tmp;

	struct bpf_prog *fp, *fp_old;

	struct bpf_prog *fp;

	u16 bpf_size, bpf_len;

	u32 classid;

	int ret;
@@ -197,26 +205,15 @@ static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, 
	if (ret)

		goto errout_free;



	tcf_tree_lock(tp);

	fp_old = prog->filter;

	bpf_old = prog->bpf_ops;



	prog->bpf_len = bpf_len;

	prog->bpf_ops = bpf_ops;

	prog->filter = fp;

	prog->res.classid = classid;

	tcf_tree_unlock(tp);



	tcf_bind_filter(tp, &prog->res, base);

	tcf_exts_change(tp, &prog->exts, &exts);



	if (fp_old)

		bpf_prog_destroy(fp_old);

	if (bpf_old)

		kfree(bpf_old);



	return 0;



errout_free:

	kfree(bpf_ops);

errout:
@@ -244,9 +241,10 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 
			  u32 handle, struct nlattr **tca,

			  unsigned long *arg, bool ovr)

{

	struct cls_bpf_head *head = tp->root;

	struct cls_bpf_prog *prog = (struct cls_bpf_prog *) *arg;

	struct cls_bpf_head *head = rtnl_dereference(tp->root);

	struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg;

	struct nlattr *tb[TCA_BPF_MAX + 1];

	struct cls_bpf_prog *prog;

	int ret;



	if (tca[TCA_OPTIONS] == NULL)
@@ -256,18 +254,19 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 
	if (ret < 0)

		return ret;



	if (prog != NULL) {

		if (handle && prog->handle != handle)

			return -EINVAL;

		return cls_bpf_modify_existing(net, tp, prog, base, tb,

					       tca[TCA_RATE], ovr);

	}



	prog = kzalloc(sizeof(*prog), GFP_KERNEL);

	if (prog == NULL)

	if (!prog)

		return -ENOBUFS;



	tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE);



	if (oldprog) {

		if (handle && oldprog->handle != handle) {

			ret = -EINVAL;

			goto errout;

		}

	}



	if (handle == 0)

		prog->handle = cls_bpf_grab_new_handle(tp, head);

	else
@@ -281,15 +280,16 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 
	if (ret < 0)

		goto errout;



	tcf_tree_lock(tp);

	list_add(&prog->link, &head->plist);

	tcf_tree_unlock(tp);

	if (oldprog) {

		list_replace_rcu(&prog->link, &oldprog->link);

		call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);

	} else {

		list_add_rcu(&prog->link, &head->plist);

	}



	*arg = (unsigned long) prog;



	return 0;

errout:

	if (*arg == 0UL && prog)

	kfree(prog);



	return ret;
@@ -339,10 +339,10 @@ static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 


static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg)

{

	struct cls_bpf_head *head = tp->root;

	struct cls_bpf_head *head = rtnl_dereference(tp->root);

	struct cls_bpf_prog *prog;



	list_for_each_entry(prog, &head->plist, link) {

	list_for_each_entry_rcu(prog, &head->plist, link) {

		if (arg->count < arg->skip)

			goto skip;

		if (arg->fn(tp, (unsigned long) prog, arg) < 0) {