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authorJohn Fastabend <john.fastabend@gmail.com>2014-09-13 07:06:26 +0400
committerDavid S. Miller <davem@davemloft.net>2014-09-13 20:30:26 +0400
commit952313bd62589cae216a579bb7ebc76f8e290817 (patch)
tree56562cd7fa266516c22199c10e3acf4ab1e91669 /net/sched/cls_cgroup.c
parent9888faefe1327909f3acf34d1feda87a368bb858 (diff)
downloadlinux-952313bd62589cae216a579bb7ebc76f8e290817.tar.xz
net: sched: cls_cgroup use RCU
Make cgroup classifier safe for RCU. Also drops the calls in the classify routine that were doing a rcu_read_lock()/rcu_read_unlock(). If the rcu_read_lock() isn't held entering this routine we have issues with deleting the classifier chain so remove the unnecessary rcu_read_lock()/rcu_read_unlock() pair noting all paths AFAIK hold rcu_read_lock. If there is a case where classify is called without the rcu read lock then an rcu splat will occur and we can correct it. 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>
Diffstat (limited to 'net/sched/cls_cgroup.c')
-rw-r--r--net/sched/cls_cgroup.c63
1 files changed, 39 insertions, 24 deletions
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index cacf01bd04f0..3b7548759998 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -22,17 +22,17 @@ struct cls_cgroup_head {
u32 handle;
struct tcf_exts exts;
struct tcf_ematch_tree ematches;
+ struct tcf_proto *tp;
+ struct rcu_head rcu;
};
static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct tcf_result *res)
{
- struct cls_cgroup_head *head = tp->root;
+ struct cls_cgroup_head *head = rcu_dereference_bh(tp->root);
u32 classid;
- rcu_read_lock();
classid = task_cls_state(current)->classid;
- rcu_read_unlock();
/*
* Due to the nature of the classifier it is required to ignore all
@@ -80,13 +80,25 @@ static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
[TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED },
};
+static void cls_cgroup_destroy_rcu(struct rcu_head *root)
+{
+ struct cls_cgroup_head *head = container_of(root,
+ struct cls_cgroup_head,
+ rcu);
+
+ tcf_exts_destroy(head->tp, &head->exts);
+ tcf_em_tree_destroy(head->tp, &head->ematches);
+ kfree(head);
+}
+
static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
struct tcf_proto *tp, unsigned long base,
u32 handle, struct nlattr **tca,
unsigned long *arg, bool ovr)
{
struct nlattr *tb[TCA_CGROUP_MAX + 1];
- struct cls_cgroup_head *head = tp->root;
+ struct cls_cgroup_head *head = rtnl_dereference(tp->root);
+ struct cls_cgroup_head *new;
struct tcf_ematch_tree t;
struct tcf_exts e;
int err;
@@ -94,25 +106,24 @@ static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
if (!tca[TCA_OPTIONS])
return -EINVAL;
- if (head == NULL) {
- if (!handle)
- return -EINVAL;
+ if (!head && !handle)
+ return -EINVAL;
- head = kzalloc(sizeof(*head), GFP_KERNEL);
- if (head == NULL)
- return -ENOBUFS;
+ if (head && handle != head->handle)
+ return -ENOENT;
- tcf_exts_init(&head->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
- head->handle = handle;
+ new = kzalloc(sizeof(*head), GFP_KERNEL);
+ if (!new)
+ return -ENOBUFS;
- tcf_tree_lock(tp);
- tp->root = head;
- tcf_tree_unlock(tp);
+ if (head) {
+ new->handle = head->handle;
+ } else {
+ tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE);
+ new->handle = handle;
}
- if (handle != head->handle)
- return -ENOENT;
-
+ new->tp = tp;
err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
cgroup_policy);
if (err < 0)
@@ -127,20 +138,24 @@ static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
if (err < 0)
return err;
- tcf_exts_change(tp, &head->exts, &e);
- tcf_em_tree_change(tp, &head->ematches, &t);
+ tcf_exts_change(tp, &new->exts, &e);
+ tcf_em_tree_change(tp, &new->ematches, &t);
+ rcu_assign_pointer(tp->root, new);
+ if (head)
+ call_rcu(&head->rcu, cls_cgroup_destroy_rcu);
return 0;
}
static void cls_cgroup_destroy(struct tcf_proto *tp)
{
- struct cls_cgroup_head *head = tp->root;
+ struct cls_cgroup_head *head = rtnl_dereference(tp->root);
if (head) {
tcf_exts_destroy(tp, &head->exts);
tcf_em_tree_destroy(tp, &head->ematches);
- kfree(head);
+ RCU_INIT_POINTER(tp->root, NULL);
+ kfree_rcu(head, rcu);
}
}
@@ -151,7 +166,7 @@ static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
{
- struct cls_cgroup_head *head = tp->root;
+ struct cls_cgroup_head *head = rtnl_dereference(tp->root);
if (arg->count < arg->skip)
goto skip;
@@ -167,7 +182,7 @@ skip:
static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
struct sk_buff *skb, struct tcmsg *t)
{
- struct cls_cgroup_head *head = tp->root;
+ struct cls_cgroup_head *head = rtnl_dereference(tp->root);
unsigned char *b = skb_tail_pointer(skb);
struct nlattr *nest;