From: Hou Tao Date: Fri, 14 Oct 2022 11:39:45 +0000 (+0800) Subject: bpf: Use rcu_trace_implies_rcu_gp() in local storage map X-Git-Tag: v6.6.17~5932^2~413^2~1^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d39d1445d37747032e2b26732fed6fe25161cd36;p=platform%2Fkernel%2Flinux-rpi.git 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 Link: https://lore.kernel.org/r/20221014113946.965131-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index 802fc15..9dc6de1 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -88,8 +88,14 @@ void bpf_local_storage_free_rcu(struct rcu_head *rcu) { struct bpf_local_storage *local_storage; + /* If RCU Tasks Trace grace period implies RCU grace period, do + * kfree(), else do kfree_rcu(). + */ local_storage = container_of(rcu, struct bpf_local_storage, rcu); - kfree_rcu(local_storage, rcu); + if (rcu_trace_implies_rcu_gp()) + kfree(local_storage); + else + kfree_rcu(local_storage, rcu); } static void bpf_selem_free_rcu(struct rcu_head *rcu) @@ -97,7 +103,10 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu) struct bpf_local_storage_elem *selem; selem = container_of(rcu, struct bpf_local_storage_elem, rcu); - kfree_rcu(selem, rcu); + if (rcu_trace_implies_rcu_gp()) + kfree(selem); + else + kfree_rcu(selem, rcu); } /* local_storage->lock must be held and selem->local_storage == local_storage.