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bpf: Use rcu_trace_implies_rcu_gp() in local storage map
Local storage map is accessible for both sleepable and non-sleepable bpf program, and its memory is freed by using both call_rcu_tasks_trace() and kfree_rcu() to wait for both RCU-tasks-trace grace period and RCU grace period to pass. With the introduction of rcu_trace_implies_rcu_gp(), both bpf_selem_free_rcu() and bpf_local_storage_free_rcu() can check whether or not a normal RCU grace period has also passed after a RCU-tasks-trace grace period has passed. If it is true, it is safe to call kfree() directly. Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20221014113946.965131-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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@ -88,8 +88,14 @@ void bpf_local_storage_free_rcu(struct rcu_head *rcu)
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{
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struct bpf_local_storage *local_storage;
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/* If RCU Tasks Trace grace period implies RCU grace period, do
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* kfree(), else do kfree_rcu().
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*/
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local_storage = container_of(rcu, struct bpf_local_storage, rcu);
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kfree_rcu(local_storage, rcu);
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if (rcu_trace_implies_rcu_gp())
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kfree(local_storage);
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else
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kfree_rcu(local_storage, rcu);
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}
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static void bpf_selem_free_rcu(struct rcu_head *rcu)
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@ -97,7 +103,10 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu)
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struct bpf_local_storage_elem *selem;
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selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
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kfree_rcu(selem, rcu);
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if (rcu_trace_implies_rcu_gp())
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kfree(selem);
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else
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kfree_rcu(selem, rcu);
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}
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/* local_storage->lock must be held and selem->local_storage == local_storage.
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