[PATCH bpf-next 3/3] bpf: Free trace program array after one RCU-tasks-trace grace period

[Hou Tao <houtao@huaweicloud.com>]

From: Hou Tao <houtao1@huawei.com>

To support sleepable uprobe bpf program, the freeing of trace program
array chains a RCU-tasks-trace grace period with a normal RCU grace
period. But considering in the current implementation of RCU-tasks-trace
that one RCU-tasks-trace grace period implies one normal RCU grace
period, so it is not need for such chaining and it is safe to free the
array in the callback of call_rcu_tasks_trace().

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 kernel/bpf/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 711fd293b6de..f943620b55b0 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2247,12 +2247,15 @@ void bpf_prog_array_free(struct bpf_prog_array *progs)
 	kfree_rcu(progs, rcu);
 }
 
+/* Now RCU Tasks grace period implies RCU grace period, so no need to call
+ * kfree_rcu(), just call kfree() directly.
+ */
 static void __bpf_prog_array_free_sleepable_cb(struct rcu_head *rcu)
 {
 	struct bpf_prog_array *progs;
 
 	progs = container_of(rcu, struct bpf_prog_array, rcu);
-	kfree_rcu(progs, rcu);
+	kfree(progs);
 }
 
 void bpf_prog_array_free_sleepable(struct bpf_prog_array *progs)
-- 
2.29.2