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| author | Paul Menage <menage@google.com> | 2009-05-26 20:47:02 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-05-26 20:47:02 -0700 |
| commit | e65fcfd63a9a62baa5708484ff8edbe56eb3e7ec (patch) | |
| tree | 0d21a21c2b87ef1c8db600d6abed3ba3e22cdaef /net/sched | |
| parent | 7682455ec36fce70bdbad9f739de05060dedfa27 (diff) | |
| download | linux-e65fcfd63a9a62baa5708484ff8edbe56eb3e7ec.tar.gz | |
cls_cgroup: read classid atomically in classifier
Avoid reading the unsynchronized value cs->classid multiple times, since it could change concurrently from non-zero to zero; this would result in the classifier returning a positive result with a bogus (zero) classid. Signed-off-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/cls_cgroup.c | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c index 91a3db4a76f8..cc29b44b1500 100644 --- a/net/sched/cls_cgroup.c +++ b/net/sched/cls_cgroup.c @@ -104,8 +104,7 @@ static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp, struct tcf_result *res) { struct cls_cgroup_head *head = tp->root; - struct cgroup_cls_state *cs; - int ret = 0; + u32 classid; /* * Due to the nature of the classifier it is required to ignore all @@ -121,17 +120,18 @@ static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp, return -1; rcu_read_lock(); - cs = task_cls_state(current); - if (cs->classid && tcf_em_tree_match(skb, &head->ematches, NULL)) { - res->classid = cs->classid; - res->class = 0; - ret = tcf_exts_exec(skb, &head->exts, res); - } else - ret = -1; - + classid = task_cls_state(current)->classid; rcu_read_unlock(); - return ret; + if (!classid) + return -1; + + if (!tcf_em_tree_match(skb, &head->ematches, NULL)) + return -1; + + res->classid = classid; + res->class = 0; + return tcf_exts_exec(skb, &head->exts, res); } static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle) |