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| author | Paolo Abeni <pabeni@redhat.com> | 2018-07-30 14:30:43 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-07-30 09:31:13 -0700 |
| commit | 7fd4b288ea6a3e45ad8afbcd5ec39554d57f1ae0 (patch) | |
| tree | 6d839e231aeb7764681d03ef13732b0fd408ff72 /net/sched/act_vlan.c | |
| parent | 802bfb19152c0fb4137c6ba72bcf042ee023e743 (diff) | |
| download | blackbird-op-linux-7fd4b288ea6a3e45ad8afbcd5ec39554d57f1ae0.tar.gz blackbird-op-linux-7fd4b288ea6a3e45ad8afbcd5ec39554d57f1ae0.zip | |
tc/act: remove unneeded RCU lock in action callback
Each lockless action currently does its own RCU locking in ->act().
This allows using plain RCU accessor, even if the context
is really RCU BH.
This change drops the per action RCU lock, replace the accessors
with the _bh variant, cleans up a bit the surrounding code and
documents the RCU status in the relevant header.
No functional nor performance change is intended.
The goal of this patch is clarifying that the RCU critical section
used by the tc actions extends up to the classifier's caller.
v1 -> v2:
- preserve rcu lock in act_bpf: it's needed by eBPF helpers,
as pointed out by Daniel
v3 -> v4:
- fixed some typos in the commit message (JiriP)
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/act_vlan.c')
| -rw-r--r-- | net/sched/act_vlan.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c index ad37f308175a..15a0ee214c9c 100644 --- a/net/sched/act_vlan.c +++ b/net/sched/act_vlan.c @@ -40,11 +40,9 @@ static int tcf_vlan(struct sk_buff *skb, const struct tc_action *a, if (skb_at_tc_ingress(skb)) skb_push_rcsum(skb, skb->mac_len); - rcu_read_lock(); - action = READ_ONCE(v->tcf_action); - p = rcu_dereference(v->vlan_p); + p = rcu_dereference_bh(v->vlan_p); switch (p->tcfv_action) { case TCA_VLAN_ACT_POP: @@ -61,7 +59,7 @@ static int tcf_vlan(struct sk_buff *skb, const struct tc_action *a, case TCA_VLAN_ACT_MODIFY: /* No-op if no vlan tag (either hw-accel or in-payload) */ if (!skb_vlan_tagged(skb)) - goto unlock; + goto out; /* extract existing tag (and guarantee no hw-accel tag) */ if (skb_vlan_tag_present(skb)) { tci = skb_vlan_tag_get(skb); @@ -86,18 +84,15 @@ static int tcf_vlan(struct sk_buff *skb, const struct tc_action *a, BUG(); } - goto unlock; - -drop: - action = TC_ACT_SHOT; - qstats_drop_inc(this_cpu_ptr(v->common.cpu_qstats)); - -unlock: - rcu_read_unlock(); +out: if (skb_at_tc_ingress(skb)) skb_pull_rcsum(skb, skb->mac_len); return action; + +drop: + qstats_drop_inc(this_cpu_ptr(v->common.cpu_qstats)); + return TC_ACT_SHOT; } static const struct nla_policy vlan_policy[TCA_VLAN_MAX + 1] = { |
