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bpf, sched: Remove unneeded rcu_read_lock() around BPF program invocation

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The rcu_read_lock() call in cls_bpf and act_bpf are redundant: on the TX
side, there's already a call to rcu_read_lock_bh() in __dev_queue_xmit(),
and on RX there's a covering rcu_read_lock() in
netif_receive_skb{,_list}_internal().

With the previous patches we also amended the lockdep checks in the map
code to not require any particular RCU flavour, so we can just get rid of
the rcu_read_lock()s.

Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210624160609.292325-7-toke@redhat.com
This commit is contained in:
Toke Høiland-Jørgensen
2021-06-24 18:05:56 +02:00
committed by Daniel Borkmann
parent 782347b6bc
commit 77151ccf10
2 changed files with 0 additions and 5 deletions
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2
net/sched/act_bpf.c
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@@ -43,7 +43,6 @@ static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
tcf_lastuse_update(&prog->tcf_tm); tcf_lastuse_update(&prog->tcf_tm);
bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb);
rcu_read_lock();
filter = rcu_dereference(prog->filter); filter = rcu_dereference(prog->filter);
if (at_ingress) { if (at_ingress) {
__skb_push(skb, skb->mac_len); __skb_push(skb, skb->mac_len);
@@ -56,7 +55,6 @@ static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act,
} }
if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK) if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK)
skb_orphan(skb); skb_orphan(skb);
rcu_read_unlock();
/* A BPF program may overwrite the default action opcode. /* A BPF program may overwrite the default action opcode.
* Similarly as in cls_bpf, if filter_res == -1 we use the * Similarly as in cls_bpf, if filter_res == -1 we use the

3
net/sched/cls_bpf.c
View File

@@ -85,8 +85,6 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
struct cls_bpf_prog *prog; struct cls_bpf_prog *prog;
int ret = -1; int ret = -1;
/* Needed here for accessing maps. */
rcu_read_lock();
list_for_each_entry_rcu(prog, &head->plist, link) { list_for_each_entry_rcu(prog, &head->plist, link) {
int filter_res; int filter_res;
@@ -131,7 +129,6 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
break; break;
} }
rcu_read_unlock();
return ret; return ret;
} }