From: Hou Tao <houtao1@xxxxxxxxxx>
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@xxxxxxxxxx>
---
kernel/bpf/core.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 711fd293b6de..4bc5f46d7030 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2251,8 +2251,14 @@ 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);
- kfree_rcu(progs, rcu);
+ if (rcu_trace_implies_rcu_gp())
+ kfree(progs);
+ else
+ kfree_rcu(progs, rcu);
}
void bpf_prog_array_free_sleepable(struct bpf_prog_array *progs)
--
2.29.2
