Commit 4835f9ee authored Oct 14, 2022 by Hou Tao Committed by Alexei Starovoitov Oct 18, 2022

bpf: Use rcu_trace_implies_rcu_gp() for program array freeing



To support both sleepable and normal uprobe bpf program, the freeing of
trace program array chains a RCU-tasks-trace grace period and a normal
RCU grace period one after the other.

With the introduction of rcu_trace_implies_rcu_gp(),
__bpf_prog_array_free_sleepable_cb() 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 invoke kfree() directly.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221014113946.965131-5-houtao@huaweicloud.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent d39d1445

kernel/bpf/core.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -2251,7 +2251,13 @@ static void __bpf_prog_array_free_sleepable_cb(struct rcu_head *rcu)
		{
		struct bpf_prog_array *progs;

		/* If RCU Tasks Trace grace period implies RCU grace period, there is
		* no need to call kfree_rcu(), just call kfree() directly.
		*/
		progs = container_of(rcu, struct bpf_prog_array, rcu);
		if (rcu_trace_implies_rcu_gp())
		kfree(progs);
		else
		kfree_rcu(progs, rcu);
		}