From: Hou Tao <houtao1@xxxxxxxxxx>
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@xxxxxxxxxx>
---
kernel/bpf/bpf_local_storage.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c
index 802fc15b0d73..9dc6de1cf185 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.
--
2.29.2
