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>
size_t size;
struct module *owner;
int (*act)(struct sk_buff *, const struct tc_action *,
- struct tcf_result *);
+ struct tcf_result *); /* called under RCU BH lock*/
int (*dump)(struct sk_buff *, struct tc_action *, int, int);
void (*cleanup)(struct tc_action *);
int (*lookup)(struct net *net, struct tc_action **a, u32 index,
/* Fast access part */
struct tcf_proto __rcu *next;
void __rcu *root;
+
+ /* called under RCU BH lock*/
int (*classify)(struct sk_buff *,
const struct tcf_proto *,
struct tcf_result *);
u32 update_flags;
int action;
- rcu_read_lock();
- params = rcu_dereference(p->params);
+ params = rcu_dereference_bh(p->params);
tcf_lastuse_update(&p->tcf_tm);
bstats_cpu_update(this_cpu_ptr(p->common.cpu_bstats), skb);
action = READ_ONCE(p->tcf_action);
if (unlikely(action == TC_ACT_SHOT))
- goto drop_stats;
+ goto drop;
update_flags = params->update_flags;
switch (tc_skb_protocol(skb)) {
break;
}
-unlock:
- rcu_read_unlock();
return action;
drop:
- action = TC_ACT_SHOT;
-
-drop_stats:
qstats_drop_inc(this_cpu_ptr(p->common.cpu_qstats));
- goto unlock;
+ return TC_ACT_SHOT;
}
static int tcf_csum_dump(struct sk_buff *skb, struct tc_action *a, int bind,
struct tcf_ife_params *p;
int ret;
- rcu_read_lock();
- p = rcu_dereference(ife->params);
+ p = rcu_dereference_bh(ife->params);
if (p->flags & IFE_ENCODE) {
ret = tcf_ife_encode(skb, a, res, p);
- rcu_read_unlock();
return ret;
}
- rcu_read_unlock();
return tcf_ife_decode(skb, a, res);
}
tcf_lastuse_update(&m->tcf_tm);
bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
- rcu_read_lock();
m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
m_eaction = READ_ONCE(m->tcfm_eaction);
retval = READ_ONCE(m->tcf_action);
- dev = rcu_dereference(m->tcfm_dev);
+ dev = rcu_dereference_bh(m->tcfm_dev);
if (unlikely(!dev)) {
pr_notice_once("tc mirred: target device is gone\n");
goto out;
if (tcf_mirred_is_act_redirect(m_eaction))
retval = TC_ACT_SHOT;
}
- rcu_read_unlock();
return retval;
}
bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
retval = READ_ONCE(s->tcf_action);
- rcu_read_lock();
- psample_group = rcu_dereference(s->psample_group);
+ psample_group = rcu_dereference_bh(s->psample_group);
/* randomly sample packets according to rate */
if (psample_group && (prandom_u32() % s->rate == 0)) {
skb_pull(skb, skb->mac_len);
}
- rcu_read_unlock();
return retval;
}
tcf_lastuse_update(&d->tcf_tm);
bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);
- rcu_read_lock();
- params = rcu_dereference(d->params);
+ params = rcu_dereference_bh(d->params);
action = READ_ONCE(d->tcf_action);
if (params->flags & SKBEDIT_F_PRIORITY)
}
if (params->flags & SKBEDIT_F_PTYPE)
skb->pkt_type = params->ptype;
-
-unlock:
- rcu_read_unlock();
return action;
+
err:
qstats_drop_inc(this_cpu_ptr(d->common.cpu_qstats));
- action = TC_ACT_SHOT;
- goto unlock;
+ return TC_ACT_SHOT;
}
static const struct nla_policy skbedit_policy[TCA_SKBEDIT_MAX + 1] = {
* then MAX_EDIT_LEN needs to change appropriately
*/
err = skb_ensure_writable(skb, MAX_EDIT_LEN);
- if (unlikely(err)) { /* best policy is to drop on the floor */
- qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
- return TC_ACT_SHOT;
- }
+ if (unlikely(err)) /* best policy is to drop on the floor */
+ goto drop;
- rcu_read_lock();
action = READ_ONCE(d->tcf_action);
- if (unlikely(action == TC_ACT_SHOT)) {
- qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
- rcu_read_unlock();
- return action;
- }
+ if (unlikely(action == TC_ACT_SHOT))
+ goto drop;
- p = rcu_dereference(d->skbmod_p);
+ p = rcu_dereference_bh(d->skbmod_p);
flags = p->flags;
if (flags & SKBMOD_F_DMAC)
ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
if (flags & SKBMOD_F_ETYPE)
eth_hdr(skb)->h_proto = p->eth_type;
- rcu_read_unlock();
if (flags & SKBMOD_F_SWAPMAC) {
u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
}
return action;
+
+drop:
+ qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
+ return TC_ACT_SHOT;
}
static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
struct tcf_tunnel_key_params *params;
int action;
- rcu_read_lock();
-
- params = rcu_dereference(t->params);
+ params = rcu_dereference_bh(t->params);
tcf_lastuse_update(&t->tcf_tm);
bstats_cpu_update(this_cpu_ptr(t->common.cpu_bstats), skb);
break;
}
- rcu_read_unlock();
-
return action;
}
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:
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);
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] = {