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Message-ID: <20140825005236.2180.5698.stgit@nitbit.x32>
Date: Sun, 24 Aug 2014 17:52:37 -0700
From: John Fastabend <john.fastabend@...il.com>
To: xiyou.wangcong@...il.com, jhs@...atatu.com, eric.dumazet@...il.com
Cc: netdev@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
brouer@...hat.com
Subject: [net-next PATCH v2 11/15] 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@...el.com>
---
net/sched/cls_bpf.c | 93 ++++++++++++++++++++++++++-------------------------
1 file changed, 47 insertions(+), 46 deletions(-)
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 0e30d58..f2ba58a 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -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 +280,17 @@ 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)
+ if (prog)
kfree(prog);
return ret;
@@ -339,10 +340,10 @@ nla_put_failure:
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) {
--
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